MADHYA PRADESH POWER TRANSMISSION CO. LTD.
SHAKTI BHAWAN RAMPUR: JABALPUR
TENDER SPECIFICATION NUMBER
PROJECT TR-30/2022
VOLUME-II
TECHNICAL SPECIFICATION FOR
400/220/33KV 500MVA POWER
TRANSFORMERS WITH OIL AND ERECTION,
TESTING & COMMISSIONING OF
TRANSFORMERS
CHIEF ENGINEER (PROCUREMENT)
CONTENTS
DESCRIPTION OF DOCUMENT
SECTION–II TECHNICAL SPECIFICATION FOR 400KV 500MVA
POWER TRANSFORMERS WITH OIL
Page No.
1-89
Annexure I
- Principal parameters
90-94
Annexure II
- List of Fittings and Accessories
95-100
Annexure III
- Test certificates to be furnished for accessories
101-104
Annexure IV
- Schedule of Inspection Windows
Annexure V
- Schedule of Valves
106-107
Annexure VI
- List of Vendors for major items
108-112
Annexure VII
- Drawings & Data to be furnished
113-115
105
Annexure VIII - Calculations required to be furnished
116-119
Annexure IX
- Details of Inspection Programme
120-124
Annexure X
- List of Hand Tools
125
Annexure XI
- Under Taking for supply of Spares
126
Drawings
4 Sheets
VOLUME II
TECHNICAL SPECIFICATION FOR 500 MVA, 400/220/33 KV
POWER TRANSFORMERS
1.0
SCOPE :
1.1
This specification covers design, engineering, manufacture, assembly, stage
inspections and testing before supply and delivery including unloading on plinth
at our substation sites located anywhere in the state of Madhya Pradesh, of the
4 nos. 400/220/33 KV, 300/400/500 MVA Auto, three phase transformers with shall
be fitted with Nitrogen Injection Fire Protection System/ Nitrogen Injection type Fire
Prevention & Extinguishing System (NIFPS), self- regenerating maintenance free
breather, RIP bushings and on line monitoring system for minimum four parameters
viz. ppm, and three key gases and all fittings, accessories, associated equipment’s
including oil for first filling including wastage & 10% extra of that quantity and
essential maintenance/ mandatory spares/equipments to be supplied alongwith
each transformer which are required for efficient and trouble free operation as
specified hereunder. Scope of supply also includes services to be provided by the
supplier/Tenderer for erection, testing & commissioning charges of each transformer
unit at each project site anywhere in MP.
1.2
It is not the intent to specify completely herein all the details of the design
and construction of equipment. However, the equipment shall conform in all
respects to high standards of engineering, design and workmanship and shall
be capable of performing the duties specified herein. The offered transformers
shall be complete with all components necessary for their effective and trouble
free operation. Such components shall be deemed to be within the scope of
TENDERER’s supply irrespective of whether those are specifically brought out in
this specification or not. The transformers should be free from Polychlorinated
Biphenyls (PVB/PCB).
1.3
The Purchaser will interpret the meanings of drawings and specification
and shall have the power to reject any work or material which, in his judgment is
not in accordance therewith. The offered transformers shall be complete with all
components necessary for their effective and trouble free operation. Such,
components shall be deemed to be within the scope of Tenderer’s supply
irrespective of whether those are specifically brought out in this specification and/or
the commercial order or not.
2.0
STANDARDS
2.1
The transformers and associated accessories shall conform to the latest
issues/amendments of standards as given below and report of the committee for
standardization of the parameters and specification of major class of 400 KV
equipment except to the extent explicitly
modified
in
this specification.
Transformers conforming to any other authoritative standards meeting better quality
and ensuring better performance are also acceptable. Tenderer shall specifically
indicate deviations if any from the INDIAN STANDARDS & IEC given in a Table-1.
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1
400KV 500 MVA Transformer
TABLE-1
APPLICABLE INDIAN/INTERNATIONAL STANDARDS FOR POWER
TRANSFORMERS AND ASSOCIATED ACCESSORIES ETC.
INDIAN
STANDARD
NUMBER
IS-2026 (Part
1 to 5 )
CBIP Publication No.295
IS-335
IS1866-2000
INTERNATIONAL
AND
INTERNATIONALLY
RECOGNISIED
STANDARD
IEC-60076(Part I to 5)
TITLE
Power Transformers
Manual on Power Transformers
Insulating oil for transformers
Electrical maintenance and Supervision of
mineral insulating oil in equipment.
IS-2099
Bushings for alternating Voltage above 1000V.
IS-2312
Fans (Cooler fans)
IS-2705.
Current Transformers.
IS-325.
Three phase Induction motors.
IS-375 &
Marking & arrangements for switch gear, bus
IS-996
bars, main connections & auxiliary wiring.
IS-3637.
Gas & oil operated relays.
IS-10028 (Part Code of practice for installation and
1to3)
maintenance of transformers.
Degree of protection provided by enclosures
IS-2147.
for low voltage switch gear and control.
IS-5.
Colors for ready mix paints.
IS-6272
Industrial cooling fans.
DOC.ETD16
Draft standard by BIS for revision of IS-6600
(3703)
for Guide for loading of oil immersed
transformers.
OLTC
IS 8478
Application Guide for OLTC
IS 10561
Application Guide for Power Transformer.
Method of measurement of Transformer Sound
IS 13964
levels.
IS 2071 (Part Methods of High Voltage Testing
1 to 3)
IS 6209
Methods for Partial Discharge Measurements
IS 2165
Insulation Coordination
IS 5561
Terminal connectors
Short Circuit Current – calculation of effects
Shunt Reactors, Neutral/Earthing Reactor and
IS-5553
Arc Suppression Coil
IS:335
Insulating oils for transformers and switchgears
Volume-II
2
IEC-296,BS-148.
IEC-60137(2008)
IEC 60044
IEC-34.
IEC 60529, IEC60947
IEC 60354
IEC 60214
IEC 60542
IEC 60076-8
NEMA-TR1
IEC 60060
IEC 60270
IEC 60071
IEC 865(part I & II)
IEC 60076-6
IEC:60296, BS:223
400KV 500 MVA Transformer
INDIAN
STANDARD
NUMBER
IS -1886
TITLE
Code of practice for installation and
maintenance of transformers.
Supervision and Maintenance guide for Mineral
Insulating Oil in Electrical Equipment
Method of Sampling of Liquid dielectrics
Guide for the Sampling of Gases and of Oil
from Oil-filled Electrical Equipment for the
Analysis of Free and Dissolved Gases
Digital Recorders and Software for High
Voltage Impulse testing
Specification for radio disturbance and
immunity measuring apparatus
Guidelines for conducting design reviews for
transformers 100 MVA and 123 kV and above.
Metal oxide surge arrestors without gaps
Selection and application recommendation
Indian Electricity Rule 1956
INTERNATIONAL
AND
INTERNATIONALLY
RECOGNISIED
STANDARD
IEC 60422
IEC 60475
IEC 60567
IEC 61083
CISPR 16
Cigre Publication 202
IEC 99-4
IEC 99-5
2.2
In case equipment conforms to other International standards which ensure
equivalent or better performance than specified under cl 2.0 then the English
version of such standards or the relevant extracts of same shall be forwarded
with the Tender and the salient features of comparison shall be brought out
separately in additional information schedule.
2.3
The electrical installation shall meet requirements of Indian Electricity
Rules, 1956 and IS-1886,"Code of practice for installation & maintenance of
Transformers" as amended till date.
2.4
In this Tender, the Tenderers will have to furnish confirmation in regard to
compliance of all our technical requirement. The Tender should clearly describe
various technical particulars of the transformer as per details given in Annex. I to XI
enclosed with this specification. Based on above information all details required in
FORM & Schedules should be furnished so that we may be able to examine
whether the Tender submitted is technically and commercially acceptable or not.
Also all details and confirmation required as per Schedules will form part of
technical Tender.
2.5
It has been experienced that the weight of core lamination, weight of copper,
weight of steel, weight of Transformer Tank along with Fittings and Accessories and
quantity of oil for first filling including wastage & 10% extra of that quantity, total
weight of core + winding after assembly and total weight of transformer are
indicated in the technical Tender by the manufacturers on tentative basis and at
the time of submission of drawing, wide variations in these quantities take
place. This is not in order and it will be obligatory on the part of the Tenderer to
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400KV 500 MVA Transformer
ensure that all these details are worked out carefully and only correct figures after
proper design are offered in the technical Tender. It may be noted that at the time
of submission of final drawings, variation in these weights beyond the limits of (+)
5% shall not be permitted.
2.6
At the time of Tender opening, only the following technical particulars shall
be read out
(i)
No load, load & auxiliary losses
including stray losses
(iii) Weight of copper
(v) Quantity of oil
a. For first filling including
wastage
b. Against 10% extra of ‘a’
(ii)
Impedance voltage
(iv)
(vi)
Weight of core
Total weight of X'mer with oil
2.7
Discrepancy In Technical Particulars : It has been noticed that some of
the information furnished in the schedule of technical particulars, technical
questionnaire and price schedule do not match with each other. In order to avoid
any discrepancy, it may be noted that for the purpose of price evaluation, the
details brought out by the Tenderers in "FORM-X’ Technical Questionnaire" will be
treated as final and evaluation will be done based on the information which will
be given in this FORM-X. In case of any discrepancy in regard to information
given in any other schedule, responsibility will rest on the Tenderers. While this
condition shall be applicable for the purpose of price evaluation, at the time of
acceptance of offer, the Purchaser will have the right to take such of the values
which are advantageous to the Purchaser .
2.8
Interconnection : The transformers are meant for service as interconnecting
transformers and shall be capable of being energized either from 400 KV side or 220
KV side. The auto transformer shall be capable of being loaded at rated power on
the 400 KV and 220 KV sides with tertiary winding loaded at its full rating (lagging or
leading or mixed load). On Load Tap Changer and tertiary winding shall be suitable
for such operation. The OLTC shall be suitable for bidirectional flow of power of
linear type only.
3.0
SERVICE CONDITIONS
3.1
Climatic Conditions : The transformers and its accessories to be supplied
against this specification shall be suitable for satisfactory continuous operation
under the following tropical conditions.
1.
Location
2.
3.
4.
Max. Ambient air temp. (oC)
Min ambient air temp (oC)
Maximum daily average ambient air
temperature(oC)
Maximum yearly weighted average
temperature (oC)
5.
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4
At various substations within
the State of Madhya Pradesh
50
-5
40
32
400KV 500 MVA Transformer
6.
Maximum Relative humidity (%)
7.
8.
9.
Average annual rainfall (cm)
Max. Wind pressure (Kg/sq.m.)
Max. Altitude above mean sea level
(Metres)
10. Isoceraunic level (Average number of
thunderstorm days per year)
11. Seismic level (horizontal acceleration)
95 (sometimes reaches
saturation point.)
125
150
1000
50
0.3g
Moderately hot and humid tropical climate, conducive to rust and fungus
growth. Tropical Protection Shall conform to IS:3202 titled “ climate proofing of
electrical equipments” and BS: 1014 : titled “protection of electrical power
equipments against the climatic condition”. The transformer tank fittings and
radiators including
all accessories shall be designed to withstand seismic
acceleration equivalent to 0.3 g. Special precautions shall be taken to prevent maloperation of Buchholz relay under such condition.
3.2
Auxiliary Power Supply : Auxiliary electrical equipment shall be suitable
for operation on the following supply system.
a.
Power Devices
(like drive motors)
b.
DC Alarm, control 220 volts DC, ungrounded 2wire
&
protective (from two supply sources).
devices
c.
Lighting.
0.415KV, 3phase, 4wire 50Hz. neutral grounded AC
supply.
230V, single phase, 50Hz AC supply.
Tenderers scope include supply of interconnecting cables, terminal boxes etc.
The above supply voltage may vary as indicated below and all devices shall be
suitable for continuous operation over the entire range of voltages.
i)
AC supply : Voltage Variation of –25% to +10%;Frequency +/- 4%
ii)
DC supply : Voltage Variation of -20% to + 10%.
All
accessories
requiring
AC or DC
satisfactorily for voltage variation as above.
4.0
GENERAL TECHNICAL REQUIREMENTS
4.1
Duty Requirements
a)
Volume-II
supply
shall
perform
The transformers and all its accessories like CTs etc., shall be
designed to withstand without injury, the thermal and mechanical
effects of any external short circuit to earth and of short circuits at
the terminals considering infinite bus arrangement of values
specified as under :
400KV - 63 KA for 3 secs.
220KV - 40 KA for 3 secs.
33KV - 31.5KA for 3 secs.
5
400KV 500 MVA Transformer
b)
Over Loading : The transformer shall be capable of being loaded
in accordance with IS:6600. There shall be no limitation imposed by
windings, bushings, tap changer etc. of transformer. Transformer &
all its accessories shall be liberally rated to allow 10% over loading
at all taps on continuous basis without exceeding the temperature
limits specified in clause 6.0.
The transformer shall be capable of being operated without
danger on each tapping at the rated KVA with specified voltage
variation corresponding to the voltage of that tapping with normal
temperature rise. The design adopted to achieve this shall be
indicated in detail in the Tender.
Transformer shall be capable of operating under the natural
cooled condition up to the specified load i.e. as ONAN rating. The
forced air /oil cooling equipment shall come into operation by
pre-set contacts of winding temperature indicator and the
transformer shall operate as a forced air/oil cooled unit i.e. as
ONAF/OFAF. Cooling shall be so designed that during total failure
of power supply to cooling fans/pumps, the transformer shall be
able to operate at full load for Ten(10) minutes without the
calculated winding hot spot temperature exceeding 1400C. Also
stopping of two cooling fans/pumps should not have any effect on
the cooling system.
Transformers fitted with two coolers (cooling banks) each
capable of dissipating 50 per cent of the loss at continuous
maximum rating shall be capable of operating for 20 minutes in the
event of failure of the blowers/pumps associated with one cooler,
without the calculated winding hot spot temperature exceeding
140oC at continuous maximum rating. The transformer shall be
capable of being operated without danger at all taps and rated MVA
with specified voltage variation corresponding to the voltage of that
tap with specified temperature rise
c) Over Voltage: The transformers shall be capable of being operated
on continuous basis at 10% excess voltage than the rated
voltage specified at each tap.
4.2
Radio Interference & Noise Level:
4.2.1 The transformers shall be designed with particular attention for suppression
of maximum harmonic voltage especially the third and fifth so as to eliminate
wave form distortion and minimize interference with communication circuits.
4.2.2 The noise level, when energized at normal voltage and frequency with
fans running shall not exceed, when measured under standard conditions, the
values specified in NEMA,TR-I.
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400KV 500 MVA Transformer
4.3 Stresses : Transformer shall be capable of withstanding Electrical, thermal
and mechanical stresses on any winding caused by forces due to symmetrical or
asymmetrical external fault.
4.4
Frequency & Magnetic Induction:
4.4.1 The transformers shall be suitable for continuous operation for a frequency
variation of (+) plus (-) minus 4% from normal 50Hz without exceeding the
specified temperature rise. For considerations of over fluxing, the transformer
shall be suitable for continuous operation for values of over fluxing factor up to 1.1.
V
FN
{ -- x -- }
VN
F
The over fluxing factor being
4.4.2 The working flux density shall not exceed 1.65 Tesla for offered no load
losses and the maximum flux density in any part of core and yoke at 110% rated
voltage combined with (-) 4% frequency variation shall preferably not exceed
the value of 1.90 Tesla as per CBIP manual no 295. For manufacturing of Power
transformer, core laminations of various specifications are available and therefore
while selecting the working flux density, the Tenderers will have to comply with the
requirements of cl.4.4.1 & 4.4.3.
4.4.3 For the selected flux density, the transformer shall have minimum of
following over fluxing
capabilities, such that while meeting the above
requirement saturation of transformer core shall not take place under any
circumstances. Transformer shall accept, without injurious heating, combined
voltage & frequency fluctuation, which produces the following over fluxing
conditions :
Over Fluxing Factor
1.50
1.40
1.25
1.10
Period
Less than 2 seconds
5.0 seconds
60 seconds
Continuous
4.4.4 The maximum current density for design of power transformers within
specified limits of transformer losses shall not exceed the limits of 300 amps per
sq.cm.
4.4.5 All other requirement of magnetic circuit shall be as per latest issue of CBIP
Manual no 295.
4.4.6 The transformers shall be either core type or shell type construction, oil
immersed, ONAN/ONAF/OFAF with external heat exchangers and shall be
suitable for outdoor service as inter connecting and/or step-down transformers
suitable for parallel operation with the existing transformer having tertiary winding
already in service at the EHV substation where these transformers are to be
commissioned. The rating and electrical characteristics of the transformers shall
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400KV 500 MVA Transformer
be strictly as specified in this specification. For matching the parameters required
for parallel operation with existing unit, details shall be intimated to successful
Tenderer.
4.5
All the transformers shall be suitable for continuous operation with
frequency variation of +/- 4% from normal 50 Hz. Combined voltage &
frequency variation should not exceed the rated V/f ratio by 10 %.
5.
INSULATION
5.1
Impulse & Power Frequency Voltage Withstand Values : For rated
nominal system voltage of 33KV, 220KV & 400KV following minimum power
frequency and impulse withstand voltage should be offered for the windings.
System
Voltage
Highest
System
Voltage
33KV
220KV
400KV
36KV
245KV
420KV
Power
Frequency
Withstand
Voltages
95KV rms
395KV rms
PD at 1.5Um/√3#
Switching Surge/
Impulse
Withstand Voltage
Impulse
Withstand
Voltage
1050KV rms
250KVp
950KVp
1300KVp
# The Partial Discharge level should be ≤ 500 pico coulomb at 1.5Um/√3 (Method
2) as per IS 2026 part 3 or IEC 60076-3.
5.2
The HV/IV winding of the transformers shall have graded insulation.
The insulation class of the neutral end of the winding shall be graded to 95
KV. The 33KV winding shall have full insulation
for 33KV i.e. 250 KVp
impulse and 95 KVrms power frequency.
6.0
TEMPERATURE RISE : Each transformer shall be capable of operating
continuously at its normal rating & 10% over load condition without exceeding
temperature limits as specified below. The maximum ambient temperature shall
be taken as 50 degree C and type of cooling be suitably adopted to limit the
temperature rise within the safe limit of operation.
Type Of Cooling
Temperature-Rise
Windings
Oil
ONAN (Air natural).
o
45 C
40oC
ONAF (Air Forced)/ OFAF(Oil Forced
Air Forced)
45oC
40oC.
7.0
FREQUENCY : All the transformers shall be suitable for continuous operation
with a frequency variation of + 4% to -4% from normal 50 Hz without exceeding
the specified temperature rise.
8.0
IMPEDANCE : The percentage impedance of the power transformer shall be
12.5% between HV-IV whereas percentage impedance between IV-LV & HV-LV shall
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400KV 500 MVA Transformer
be offered as per design on its own highest MVA base i.e 500 MVA base. Tenderers
shall indicate the guaranteed impedance, tolerances and also the impedance on all
taps for the offered transformers. Impedance shall include positive and zero
sequence and shall be expressed in terms of the branches of the star connected
equivalent diagrams on all the specified MVA base and the range shall be given for
each branch of the equivalent circuit turn. It may be noted that if required the
percentage impedance
should
be designed identical to
the
existing
transformer of any make in case parallel operation is desired. The IS tolerance
on all matching taps are acceptable. Confirmation regarding requirement of
parallel operation should be given in the bid.
It may be noted by the Tenderers that for the purpose of matching
impedance of transformer, included in scope of this bid, between 400KV, 220KV
& 33KV main/ tertiary windings , the Tenderers are not permitted to use reactor or
reactor/capacitor assembly. The design of the main winding should take care of the
requirement of impedances as specified in this tender document and for this
purpose, no reactor or reactor/capacitor should be used.
9.0
GUARANTEED LOSSES AND PENALTY
9.1 Maximum Losses : While the Bidders may offer their own design, it may be
noted that the transformer losses at 75 deg. C at rated output, rated Voltage and
rated frequency should not exceed the following maximum limits which include
tolerances as per IS :
a) No load losses (Iron losses): 90 KW
b) Load(Copper losses) + Auxiliary losses: 500KW
including stray loss in KW
c) Copper losses in KW : 388 KW
d) Stray plus eddy losses in KW: 97 KW
e) Auxiliary losses in KW : 15 KW
Note:- May please note that losses are fixed and evaluation shall be carried
out on pass fail basis, no capitalization shall be done. Bidder may please note
that while quoting bid for losses shall not exceed the above limits otherwise
the offer may be treated as non-responsive.
9.2
The No load losses in kilowatts ( including BIS tolerance ) at rated voltage
and rated frequency and the total load losses in kilowatts at rated output, rated
voltage and rated frequency at 75oC shall be guaranteed by the bidder.
Successful bidder may please be note that the losses of the Transformer shall not
exceed +2% during final testing of the transformer, if the same exceeds from the
maximum ceiling limit of Transformer losses as detailed in 9.1 above then the
Transformer shall be liable for rejection. No benefit shall be given for supply of
transformer, with losses (measured during routine tests) less than the losses
specified. The penalty shall be recovered as detailed under but as a exception only
first unit upto +2% excess losses may be accepted within penalty on excessive
losses:Volume-II
9
400KV 500 MVA Transformer
S.
No
1
2
3
Differential of specified losses vs
Measured losses
No load Loss
I²R Losses/Load Losses
(Differential of whichever loss is higher shall
be considered for penalty)
Auxiliary Losses
RATE
(in INR per KW)
Rs. 10,00,000/KW
Rs. 8,00,000/KW
Rs. 8,00,000/KW
Note: For a fraction of a KW, the penalty shall be applied on prorate basis
9.3 Four (04) Nos. 500 MVA 400 KV power transformer has been included in
this specification and out of ordered quantity, one no. power transformer
shall be subject to heat run test (Temperature rise test).
9.4
TERTIARY:
9.4.1 For 500 MVA transformer, OFAF rating of HV & IV shall be 500 MVA and
that of 33 KV tertiary rating shall be 167 MVA. The tertiary of 500 MVA transformer
shall be designed for full rated MVA loading of either capacitive or inductive or mixed
load. The tertiary winding shall not have taps i.e. Tertiary winding shall be without
tap changer.
9.4.2 Tertiary winding may be used for connecting switched type reactors or
synchronous condensers with individual phase ratings of 40/50 MVAR or
station transformer with 33 KV CT/PT & associated equipment. The winding
shall be able to withstand frequent switching in and out many times every day
of such reactors and synchronous condenser. The tertiary winding is intended
to be loaded for the specified rating as mentioned above and accordingly
terminals of delta winding needs to be brought out on transformer through
three bushings.
9.4.3 One 33 KV class, turret mounted type, separate CT of ratio 1600/1-1
Amps having two secondary cores of rating 1Amp, one of accuracy class 5P10
and other of accuracy class 1 shall be provided for monitoring circulating
current and also to provide protection against circulating current beyond
rated capacity. For measurement of circulating current of delta winding, one
Ampere meter of digital /numeric type suitable for specified CT ratio shall be
provided on the RTCC panel. In case size of CT is large provision of separate
CT with structure shall be included within the offered price. The tertiary
winding shall be designed to carry the fault current under worst fault
condition.
10.0 COOLING : The Tenderer may offer ONAN/ ONAF/ OFAF type of cooling for
these Transformer. Each transformer shall be provided with two sets of radiator
banks each rated for affording 50% cooling and required number of air blast fans
and oil pumps for normal operation. Each of the two (50% rated) radiator banks shall
have stand by fans. There shall be two oil pumps for each Bank rated for 100% duty,
Volume-II
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400KV 500 MVA Transformer
one of the oil pumps being stand by for each Bank. The OFAF cooling
two groups each of 50% capacity. Adequate number of fans and
pump for providing additional 20 % cooling capacity as standby shall
separately duly mounted and wired for each group/bank of coolers
requirement indicated in clause 15.1 ( C ).
shall be in
one cooling
be provided
in line with
11.0 CONSTRUCTION DETAILS : The features and construction details of power
transformer shall be in accordance with the requirements stated hereunder:
11.1
Tank :
(A)
As required in CBIP specification, the tank shall be of Bell type
construction for 500 MVA transformers covered under this
specification. Top cover of Bell type construction shall be welded to
the tank body .
(B)
Tank shall be of welded construction and fabricated from tested
quality low carbon steel. The base of the tank on the unit shall be
so designed that it can be possible to move the complete unit by
skidding in any direction without damages when using plate or rail
and the tank plate thickness shall be as follows.
Length of tank (m)
Flat bases
Over 2.5m but less than 5m
Over 5 m but less than 7.5m
Over 7.5m
Minimum plate
thickness (mm)
20
26
32
(C) All seams and those joints not required to be opened at site shall be
factory welded and wherever possible they shall be double
welded. After completion of tank construction and before painting,
'Dye Penetration Test' shall be carried out on welded parts of
jacking bosses, lifting lugs and all load bearing members.
(D) Tank stiffeners shall be provided for general rigidity and these shall
be designed to prevent retention of water.
Volume-II
(E)
The tanks shall be designed to withstand the following
without
permanent distortion.
(i) Mechanical shocks during transportation.
(ii) Vacuum filling of oil at 10 milli torr in transformer with all
fittings.
(iii) Continuous internal pressure of 35 kN/m2 over normal
hydrostatic pressure of oil.
(iv) Short circuit forces &
(v) Under seismic condition /events both horizontal/vertical .
(F)
Where ever possible the transformer tank and its accessories shall
be designed without pockets wherein gas may collect. Where
11
400KV 500 MVA Transformer
pockets cannot be avoided, pipes shall be provided to vent the gas
into the main expansion pipes if any.
(G) The shields shall be such that no magnetic fields shall exist outside
the tank. They shall be of magnetically permeable material. If
required impermeable shields shall be provided at the coil ends.
Tank shield shall not resonate when excited at the natural frequency
of the equipment. Tenderer shall confirm use of tank shields in the
schedule of additional information.
(H) The tank shall be provided with :
(I)
(i)
Lifting lugs suitable for lifting the equipment complete with
oil.
(ii)
A minimum of four jacking pads in accessible position at
500mm height to enable the transformer complete with oil to
be raised or lowered using hydraulic or screw jacks. The
location of jacking pads shall be such that there should not be
any interference with the civil foundation of rails in either
direction i.e. longitudinal or transverse.
(iii)
Suitable haulage holes shall be provided.
(i)
Inspection cover/access windows & Manholes: Suitable
man-hole with a welded flange and a properly gasketted
bolted cover having of minimum thickness of 10 mm shall be
provided on the tank cover. The man-hole shall be of
sufficient size to offer easy access to the lower ends of the
bushings, terminal
etc. The
requirement of inspection
windows and manholes have been stipulated in AnnexureIV & Tenderers have to confirm compliance of the same in
their offer.
Space for free movement in Transformer Tank for
inspection:
Details of passage & free space provided inside the main
tank should be indicated in concerned drawing to allow free
movement of at-least two persons for inspection of active parts
etc. To be more specific it may please be noted that minimum
clearance from outer most winding/connection leads/
support to tank shall not be less than 300 mm on all 4
sides with suitable platform on bottom of the tank to
facilitate free movement of person all around inside the
tank.
All bolted connections to the tank shall be fitted with suitable oil
tight gaskets which shall give satisfactory
service under all
operating conditions. Special attention shall be given to the
methods of making the hot oil tight joints between the tank and the
cover as also between the cover and the bushings and all other
outlets to ensure that the joints can be remade satisfactorily and
easily with the help of semi skilled labor. Where compressible
(ii)
(J)
Volume-II
12
400KV 500 MVA Transformer
gaskets are used, stoppers/ runners shall be provided to prevent
over compression.
(K) Suitable guides shall be provided for positioning the various parts
during assembly or dismantling. Adequate space shall be provided
between the cores and windings assembly and the bottom of the
tank for collection of any sediment.
(L) The design of the tank, lifting lugs shall be such that the complete
transformer assembly filled with oil can be lifted with the use of
these lugs without any damage or distortions.
(M) For the complete transformer we have clearly brought out our
requirement of various types of valves in Annexure V enclosed
brings out details of type, size and quantity of valves which are to
be provided at various locations. This requirement has to be
confirmed by the Tenderers without any deviation.
(N) Gasketing Arrangement : It may be noted that all gasketted joints
shall be grooved one using ‘O’ rings of nitrile rubber or better, such
as the joints between bushing turret and bushing flange, inspection
covers of inspection windows and all other openings provided for the
purpose of inspection of internal parts of the transformer etc. The
main bell tank gasket between upper tank and bottom tank shall be
single piece ‘O’ ring cord/gasket of nitrile rubber or material of better
quality. The gasketting arrangement shall be grooved one with
proper stopper to avoid over compression. It is to be noted that one
additional set of gaskets shall be delivered by the Tenderer
alongwith transformer to replace the used gaskets at the time of
erection of the unit. The Gaskets to be used shall not be older than
one year for which documentary evidence regarding procurement of
gaskets shall be furnished.
Note :- All tank gaskets/O-rings used shall be of NBR (Acrylonitrile
Butadiene Rubber).The properties of all the above gaskets/O-Rings
shall comply with the requirements of type-IV rubber of IS-11149.
(O) Ladder : One detachable bolted type mild steel (MS) ladder with
anti-climbing arrangement shall be provided. Ladder for climbing up
to & over top cover of power transformers shall be mechanically
sturdy enough to bear the load of healthy maintenance staff without
any shake/jerks. The arrangement shall not be detached after
erection and commissioning of the unit, hence shall be provided with
padlock locking arrangement for anti-climbing device. On the upper
top of the ladder, provision for support shall be made. However, the
arrangement of the ladder shall be to purchaser’s approval.
Collapsible ladder shall not be acceptable to us. Also, suitable mild
steel (MS) ladder shall be provided for conservator tank.
(P) Suitable earthing bridge between upper and lower tank shall be
provided at least on four places each on HV & IV side and four place
on other both sides.
Volume-II
13
400KV 500 MVA Transformer
(Q) The thickness of transformer wheel base plate (roller mounting) shall
be 32 mm so as to avoid its bending during dragging of transformer
on rails.
(R) Tank MS plates of thickness >12 mm should undergo Ultrasonic
Test (UT) to check lamination defect, internal impurities in line with
ASTM 435 & ASTM 577.
11.2
Tank Cover
(a) The tank cover shall be sloped to prevent retention of rain water
and shall not distort when lifted.
(b) Inspection cover/man holes shall be provided as per AnnexureIV.
(c) The tank covers shall be fitted with pockets at the position of
maximum oil temperature of MCR (Maximum Continuous
Rating)
for inserting bulbs of oil and winding
temperature
indicators. It shall be possible to remove these bulbs without
lowering the oil in the tank. The thermometer shall be fitted with a
captive sensor to prevent the ingress of water.
(d) Bushings,
turrets,
covers
of
inspection
openings,
thermometer, pockets etc., shall be designed to prevent ingress
of water into or leakages of oil from the tank.
(e) All bolted connections shall be fitted with weather-proof, hot oil
resistant gasket in between, for complete oil tightness. If gasket
is compressible, metallic stoppers shall be provided to prevent overcompression.
(f)
11.3
A minimum of three nos. PRD i.e. one each shall be
provided above each phase winding.
Undercarriage
(a) The transformer tank shall be supported on a structural steel base
equipped with forged steel or cast steel single flanged wheels
suitable for moving the transformer completely filled with oil. If
necessary, the wheel assembly should consist of two wheels for
each point. Provision shall be made for mounting bidirectional
flanged rollers with locking and bolting device for rail gauge specified
below:,
(b)
Volume-II
Type of
Construction
Three Phase
Shorter axis
Longer axis
2/3/4
rail
combination Two rails with 1676
according to layout and size mm gauge
of transformer
Jacking pads/steps shall be provided. It shall be possible to
change the direction of the wheels through 90 deg. when the
transformer is lifted on jacks to permit movement of the
transformer both in longitudinal and transverse direction.
14
400KV 500 MVA Transformer
(c)
(d)
The track/rail gauge shall be 1676 mm along the longer side, as
well as along the shorter axis. However Rails shall be placed
perpendicular to the bushing line.
Pulling eyes shall be provided to facilitate movement/pulling of the
transformers and these shall be suitably braced in a vertical
direction so that bending does not occur when the pull has a vertical
component.
11.4
Axles And Wheels
(a) The transformers are to be provided with flanged bi-directional
wheels and axles. These shall be so designed as not to deflect
excessively to interfere with the movement of the transformer.
Wheels shall be provided with suitable bearings which shall be
rust and corrosion resistant. Fittings for lubrication shall also be
provided.
(b) Suitable locking arrangement along-with foundation bolts shall
be provided for the wheels to prevent accidental movement of
transformer. The locking arrangement shall be such that it can be
locked with plinth of transformer. The length of the arrangement
should be adequate to cover height of the rail. No floating type
locking arrangement shall be accepted.
(c) The wheels are required to swivel and they shall be arranged so
that they can be turned through an angle of 90 degrees when the
tank is jacked up to clear of rails. Means shall be provided for
locking the swivel movements in positions parallel to and at right
angles to the longitudinal axis of the tank (i.e. longitudinal &
transverse directions).
(d) To facilitate uniform distribution of transformer weight two nos. props
each on front & rear side along longer axis to be provided.
11.5
Anti Earthquake/Transport Clamping Device
(a) To prevent transformer movement during earthquake, clamping
device shall be provided for fixing transformer to the foundation.
The Tenderer shall supply necessary bolts for embedding in the
concrete foundation. The arrangements shall be such that the
transformer can be fixed to or unfastened from these bolts as
desired. The fixing of the transformers to the foundations shall be
designed to withstand seismic events to the extent that a static coefficient of 0.3g. applied in the direction of least resistance to that
loading will not cause the transformer or clamping devices as well as
bolts to be over stressed.
(b) Locking arrangement to eliminate relative movement between top
yoke/active parts with the transformer tank shall be sturdy enough to
bear transport hazards taking in to account the poor road conditions
and also considering that road transportation of transformer will not
be on hydraulic trailers .
Volume-II
15
400KV 500 MVA Transformer
11.6
Conservator Tank :
(a) The conservator tank shall be of minimum thickness of 10 mm and
it shall have adequate capacity between highest and lowest
visible levels to meet the requirement of expansion of the total
cold oil volume in the transformer and cooling equipment from
minimum ambient temperature to 100oC.
(b) The conservator tank shall be bolted into position so that it can be
removed for cleaning purposes.
(c) Magnetic oil gauge (MOG) & prismatic oil level gauge having three
overlapped windows on one side of conservator and on opposite
side of conservator, plain oil gauge with three overlapped windows
shall be provided to indicate oil level inside the conservator at
each location. Proper arrangement to ensure visibility of oil level
from ground be also ensured . Further, MOG and prismatic oil guage
shall provided for OLTC conservator.
(d) Conservator shall be provided in such a position as not to obstruct
the electrical connections to the transformer.
(e) In order to avoid congestion and to facilitate operation and
maintenance activities, the main conservator and OLTC conservator
shall be provided on opposite sides of the main tank. Further, there
shall be adequate space for manual operation of OLTC.
(f) Separate conservator tank shall be provided for OLTC.
(g) The size of the conservator shall be so designed as to accommodate
approximately 10% volume of total quantity of oil in the transformer.
(h) Suitable arrangement shall be made for providing a foot rest with
easy & access arrangement to facilitate maintenance/operation at
top of the conservator, on magnetic oil level gauge and buchholz
relay.
(i) The design of conservator shall be such that the air is not trapped
between air cell and main conservator.
(j) Conservator Protection Relay (CPR)/Air cell puncture detection relay
shall be externally installed on the top of conservator to give alarm
in the event of lowering of oil in the conservator due to puncture of
air cell in service.
(k) OLTC shall have conventional type conservator (without aircell) with
magnetic oil level gauge with potential free oil level alarm contact
and prismatic oil level gauge.
11.7
Tank
Earthing Arrangement : : Two earthing pads (150x150mm)
complete with two number tapped holes M12 bolts plain and spring washer suitable
for connection to 75x12 mm GI flat shall be provided each at position close to two
diagonally opposite bottom corners of tank. Earthing strips up to the ground level
and its connection with station earth pit shall be provided by the Tenderer.
11.8 Pressure Relief Device : A minimum of 3 (three) number of pressure
relief devices of reputed make and reliable quality shall be provided on each
transformer and these shall be mounted preferably on the tank cover above
Volume-II
16
400KV 500 MVA Transformer
each phase winding. Tenderers must submit calculations to prove that the no and
capacity of pressure relief device with location of each PRV provided on the
transformer will adequately meet our requirement. The quantity of three numbers is
on the basis that two numbers will be required as per design calculation and one
number additional PRD shall be provided from the point of view of additional safety.
Constructional and design details of pressure relief device must be furnished and it
should be proved by calculation that the size and operating pressure setting of
pressure relief device is adequate, considering the rating of the transformer and
quantity of oil in the transformer. Furnishing of this information is a must. These
PRD's shall be of sufficient size for rapid release of any pressure that may be
generated in the tank and which may result in damage to the equipment. The
device shall operate at a static pressure of less than the hydraulic test pressure of
transformer tank. It shall be mounted directly on the tank. One set of
electrically insulated contacts shall be provided for alarm & tripping along-with
the recommendations.
11.9
Relays
11.9.1 Buchholz Relay : A double float type Buchholz relay along with suitable
moulded type cover to avoid ingress of moisture/ rain water shall be provided. All the
gases evolved in the transformer shall collect in this relay. The relay shall be
provided with a test cock suitable for a flexible pipe connection for checking
its operation and for taking gas sample. A copper or stainless steel tube, shall be
connected from the gas collector to a valve located about 1200mm above ground
level to facilitate sampling of gas while the transformer is in service. The device
shall be provided with two electrically independent ungrounded contacts, one for
alarm on gas accumulation and the other for tripping on sudden rise of pressure.
The contacts of relay shall be properly housed, sealed and gasketted to make the
arrangement water proof. Entry of moisture/water in the contact chamber needs to
be eliminated. Cable entry to terminal box of buchholz relay should be made through
bottom of relay. It is further to note that the rain water protection cover is
required to be provided for the Buchholz relay.
11.9.2 Oil Surge Relay (OSR) : From our past experience, it is found that
undesired tripping of Power Transformers is occurring on oil surge relay (OSR)and
Buchholz relay operation actuating due to accumulation of water inside relay
pockets. The water accumulation takes place through entry point of cable gland.
In view of above, the design and placement of Alarm & trip contact assembly of
OSR and Buchholz Relay should be improved to take care of the following
requirements:
(a)
The cable entry to terminal box of OSR should be made through bottom
of relay. Also the OSR relay should be protected from rain water by providing
proper cover on it.
(b)
In order to ensure exit/drainage of accumulated water from inside the relay,
a fine hole should be made in terminal box of relay.
Volume-II
17
400KV 500 MVA Transformer
Note : The Tenderers shall ensure that the compartments housing relay contacts of
Pressure Relief Valve , Buchholz Relay and Oil Surge Relay are made absolutely
water and vermin proof. The compartment housing contacts of OSR,PRV and
Buchholz Relay shall be tested for water proof at the time of inspection and
effectiveness of water proofing shall be demonstrated at the time of inspection.
This should be noted carefully by the Tenderer and specifically confirmed in
their Tender. The rain water protection cover is required to be provided on the
OSR.
11.9.3 Sudden Pressure Relay/ Rapid Pressure Rise Relay: One number of
Sudden Pressure Relay/ Rapid Pressure Rise Relay with alarm or trip contact
(Terminal connection plug & socket type arrangement) shall be provided on tank of
transformer/reactor. Operating features and size shall be reviewed during design
review. Suitable canopy shall be provided to prevent ingress of rain water.
Pressurized water ingress test for Terminal Box (routine tests) shall be conducted on
Sudden Pressure Relay/ Rapid Pressure Rise Relay.
11.10 Temperature Indicator:
11.10.1 Oil Temperature Indicator (OTI) :Transformers shall be provided with a
150mm dial type thermometer with maximum pointer for top oil temperature
indication. The thermometer shall have adjustable two electrically isolated heavy
duty alarm and trip contacts, maximum reading pointer and resetting device
mounted in the Fan control cubicle (FCC). A temperature sensing element
suitably located in a pocket on top oil shall be provided. This shall be connected
to the OTI by means of capillary tubing. Accuracy class of OTI shall be plus or
minus 1.0% or better. The OTI shall be provided with anti-vibration mounting.
Note:- Temperature transducer with PT100 sensor :
RTD shall be provided with PT100 temperature sensor having nominal resistance of
100 ohms at zero degree centigrade. The PT100 temperature sensor shall have
three wire ungrounded system. The calibration shall be as per IS 2848 or equivalent.
The PT100 sensor may be placed in the pocket containing temperature sensing
element. RTD shall include image coil for OTI system and shall provide dual output
4-20mA for SCADA system. The transducer shall be installed in the Individual
Marshaling Box. Any special cable required for shielding purpose, for connection
between PT100 temperature sensor and transducer, shall be in the scope of
manufacturer. 4-20mA signal shall be wired to Digital RTCC panel/BCU for further
transfer data to SCADA through IS/IEC 61850 compliant communications.
11.10.2 Winding Temperature Indicator (WTI):(a)
Volume-II
WTI for measuring the winding temperature of each of the
windings (HV, IV, Tertiary) shall be provided. It shall comprise of
the following
(i)
Temperature sensing element.
(ii)
Image coil.
18
400KV 500 MVA Transformer
(iii)
Auxiliary CTs, if required, to match the image coil, shall be
provided.
(iv) 150mm dia local indicating instrument with maximum
reading pointer mounted in FCC/marshalling box and with four
adjustable electrically isolated heavy duty contacts (two for
control of cooling equipment, one for high winding
temperature alarm and other for trip) shall be provided. The
WTI shall be provided with anti vibration mounting.
(b)
(c)
(d)
(e)
(f)
(v) Calibration device.
In addition to the (a) above, repeater dial of WTI for each winding
shall be provided for Remote winding temperature indication. It
shall be suitable for flush mounting on RTCC panel. A precision
potentiometer mounted inside the case shall function as a
transmitter to operate a repeater for RWTI. For two windings(i.e.
HV and IV) the transmitter shall be directly connected to the
repeater. For the third winding i.e. LV(Tertiary) the transmitter
shall be connected to a resistance Transducer, which will
supply DC for operating repeater.
Auxiliary supply, if required in RTCC panel for RWTI, shall be 220V
DC only.
Accuracy class of WTI shall be plus or minus 1.0% or better.
Any special cables required for shielding purpose for connection
between cooler control cabinet and remote winding temperature
indicator control circuit shall be in Tenderer’s scope of work.
WTI CT ratio shall be embossed on secondary winding terminal box.
Note :i) Some of the manufacturers have a practice to directly install winding
temperature indicator (WTI) and oil temperature indicator (OTI) on the body
of the transformer in open. This is not acceptable & it is obligatory on the
part of the BIDDERs to enclose OTI & WTI and all such accessories in a
separate Fan Control Cubicle (FCC) cum Marshalling Box .
ii) Temperature transducer with PT100 sensor for each winding: RTD shall be
provided with PT100 temperature sensor having nominal resistance of 100
ohms at zero degree centigrade. The PT100 temperature sensor shall have
three wire ungrounded system. The calibration shall be as per IS 2848 or
equivalent. The PT100 sensor may be placed in the pocket containing
temperature sensing element. RTD shall include image coil, Auxiliary CTs, if
required to match the image coil, for WTI system and shall provide dual output
4-20mA for remote WTI and SCADA system individually. The transducer and
Auxiliary CT shall be installed in the Individual Marshaling Box. Any special
cable required for shielding purpose, for connection between PT100
temperature sensor and transducer, shall be in the scope of Contractor. 420mA signal shall be wired to Digital RTCC / BCU panel for further transfer
data to SCADA through IS/IEC 61850 compliant communications.
Volume-II
19
400KV 500 MVA Transformer
11.11
Core
a)
The core shall be constructed from high grade, non- ageing, low
loss, Cold Rolled Super Grain oriented (CRGO) silicon steel
laminations of HI-B grade steel or better. All stipulations under
clause 4.4 should be considered while selecting material of core.
Core shall be preferably 5 limbed construction.
Interlamination resistance shall be as per BS 601 Part 5 method
of July 1973. The Tenderer shall furnish the details of steel
laminations i.e. type alongwith hysterisis loss curve (B-H curve)
etc.
b)
The hot spot temperature and surface temperatures in the core shall
be calculated for over voltage conditions specified in the document
and it shall not exceed 125 deg C and 120 deg C respectively. After
being sheared, the laminations shall be treated to remove all
burrs and shall be re-annealed to remove all residual stresses.
(c)
The design of the magnetic circuit shall be such as to avoid static
discharges, development of short circuit paths within itself or to the
earthed clamping structure and production of flux component at
right angles to the plane of laminations which may cause local
heating.
The core shall be provided with lugs suitable for lifting complete core
& coil assembly of transformer.
Core Belting : The core shall be rigidly clamped by belting to
ensure adequate mechanical strength. Core and winding shall be
capable of withstanding the vibrations & shock during transport,
installation, service and adequate provision shall be made to
prevent movement of core & winding relative to tank during these
conditions. The location, size and material of belting shall be
clearly indicated in drawing which shall be submitted with
Tender. Bolted type core construction shall not be acceptable.
All steel sections used for supporting the core shall be thoroughly
sand blasted after cutting, drilling and welding.
Each core lamination shall be insulated with a material that will not
deteriorate due to pressure and hot oil.
The insulation of core to clamps plates shall be able to
withstand a voltage of 2 KV RMS for one minute.
The maximum flux density in any part of the core and yoke at rated
MVA, 110% voltage and (-) 4% frequency at any tap shall not
exceed 1.90 Tesla. The Tenderer shall provide saturation curve of
the core material proposed to be used and calculations to
demonstrate that the core is not over fluxed under stringent
condition of transformer operation.
Tenderer will offer the core for inspection & approval by the
purchaser during the manufacturing stage. Tenderer’s call
(d)
(e)
(f)
(g)
(h)
(i)
(j)
Volume-II
20
400KV 500 MVA Transformer
notice for this purpose should be accompanied with the
following documents, as applicable, as a proof towards use of
prime core material.
i)
Invoice of the supplier
ii) Mill's Test Certificate
iii) Packing List
iv) Bill of lading
v) Bill of entry certificate by customs.
(k) Core material shall be directly procured either from the
manufacturer
or
through
their
accredited
marketing
organization of repute and not through any agent.
(l) Tenderer should have in-house Core Cutting facility for proper
monitoring & control on quality and also to avoid any possibility of
mixing of prime material with defective/second grade material.
However, in case if in house core cutting facility is not available at
manufacturers works in that case cutting from other sources shall
also be accepted subject to condition that manufacturer shall be
solely responsible for proper monitoring & control on quality and also
to avoid any possibility.
(m) Oil ducts shall be provided wherever necessary to ensure adequate
cooling. The winding structure and major insulation shall not obstruct
the free flow of oil through such ducts. Where the magnetic circuit is
divided into pockets by cooling ducts parallel to the plane of
laminations or by insulating material above 0.254 mm. Thick, tinned
copper strip bridging pieces shall be inserted to maintain electrical
continuity between pockets. The design of the magnetic circuit shall
be such as to avoid static discharge development of short circuit
path within itself or to the earthed clamping structure and production
of flux components at right angles to the plane of the laminations
which may cause local heating.
(n) Considering that the requirement is for three phase auto-transformer
with tertiary delta, it is expected that the Tenderer may offer
transformer design with five limb core. Details in this respect shall
be furnished.
(o) Core shall not directly rest on the bottom metal sheet of transformer
tank. Around 5 mm or more free space for oil insulation shall be
made between the core and bottom sheet of transformer tank. A 5
mm FRP Insulating sheet shall be provided to take care of core
earthing due to accidental slippage of stampings. Also in
addition to this extra insulation thickness of 5 mm or more FRP
sheet be provided at the bottom of resting shoes of end frame
with proper fixing arrangement to avoid accidental slippage,
damages etc.
Volume-II
21
400KV 500 MVA Transformer
11.12 Windings:
(a)
(b)
(c)
(d)
(e)
(f)
(g)
(h)
Volume-II
The Tenderer shall ensure that windings of all transformers are
made in dust proof, conditioned atmosphere. The Tenderer shall
furnish the facilities available at their works alongwith the
Tender.
The conductors shall be of electrolytic grade copper as per relevant
IS. The maximum current density for design of transformers within
specified limits of transformer losses shall not exceed the limits of
300 amps per sq.cm.
The insulation of transformer windings and connections shall be
free from insulating compounds which are liable to soften, ooze
out, shrink or collapse or be catalytic and chemically active in
transformer oil during service.
Coil assembly and insulating spacers shall be so arranged as to
ensure free circulation of oil and to reduce the hot spot of the
winding. The conductor shall be transposed at sufficient intervals in
order to minimize eddy currents and equalize the distribution of
currents and temperature along the winding.
The LV (tertiary) winding should withstand short circuit faults/forces
of the transformer upto the prescribed fault levels on HV & IV sides
against mechanical and thermal stresses. To avoid damage to
tertiary windings due to high stresses at the time of severe short
circuit it is desirable that some special constructional features like
encasing the tertiary windings by epoxy compound etc is done as
per tenderers practice. Tenderer shall elucidate the constructional
features adopted by them for the same. Special constructional and
design features adopted for avoiding displacement of coils/clamping
structure during dynamic short circuit conditions be given.
Best insulating material shall be used and compression of the
windings after drying out shall be carried out at a pressure
exceeding one and a half to twice the force which can occur in the
transformer; to impart greater mechanical strength to the windings
against heavy short circuit stresses.
The windings shall be so designed that all coil assemblies of
identical voltage ratings shall be interchangeable and field repairs
to the windings can be made readily without special equipment.
The coils shall be supported between adjacent sections by
insulating spacers, and the bracings and other insulation used in
the assembly of the winding shall be arranged to ensure free
circulation of the oil to reduce hot spots in the windings.
The coil insulation shall be treated with suitable insulating varnish
or equivalent compound wherever necessary to develop the full
electrical strength of the winding. All materials used in the insulation
and assembly of the winding shall be insoluble, non-catalytic and
22
400KV 500 MVA Transformer
chemically inactive in the hot transformer oil and shall not soften or
otherwise be adversely affected under the operating conditions.
(i)
All threaded connections shall be provided with locking facilities.
All leads from the winding to the terminal connectors and
bushings shall be rigidly supported to prevent injury from vibration.
Guide tubes shall be used where practicable.
(j)
Windings shall be subjected to a shrinkage treatment before final
assembly so that no further shrinkage occurs during service.
Adjustable device shall be provided for taking up any possible
shrinkage of coils in service. After shrinkage process, the windings
shall be clamped securely in place so that they will not be displaced
or deformed during short circuits. The assembled core and
windings shall be vacuum-dried and suitably impregnated before
removal from the treating tank. The copper conductors used in the
coil structure shall be best suited to the requirements and all
permanent current carrying joints in the windings and the leads
shall be crimped or brazed preferably by high frequency
brazing system shall be finalized at the time of drawing approval.
It is observed that many manufacturers are using sectored clamping
arrangement at top as well as bottom for clamping of the windings.
This type of arrangement is considered to be not suitable for EHV
grade power transformers. In this regard, it may be noted that both
top & bottom clamping rings to be provided for clamping of windings
shall be of one piece single ring. The top & bottom clamping rings
should be of minimum thickness 60 mm thk with proper safety
margins based on design and shall be in one piece to make the
clamping arrangement sturdy. Sectored pressure/clamping
rings are not acceptable. The single pressing/clamping ring
shall be provided with adequate number of pressure/jacking
points as per design. Since sectored ring arrangement shall
not be accepted hence Tenderer should ensure and confirm
this specific requirement in the technical questionnaire. In case
of non availability of pressing/ clamping ring in single piece
suitable for offered rating transformer, issue will be discussed
& finalized at the time of drawing approval for use of a ring in
two pieces. However, MPPTCL decision in this regard will be
final and binding on the supplier.
(k)
Tenderer will offer the Copper and insulating material for windings
for inspection & approval by the purchaser
during
the
manufacturing stage. Tenderer’s call notice for the purpose
should be accompanied with the following
documents, as
applicable, as a proof towards use of prime Copper and insulating
material for windings .
i)
ii)
iii)
Volume-II
Invoice of the supplier
Mill's Test Certificate
Packing List
23
400KV 500 MVA Transformer
iv)
v)
(l)
Bill of lading
Bill of entry certificate by customs.
Core, Copper and insulating material for windings shall be directly
procured either from the manufacturer or through their accredited
marketing organization of repute and not through any agent.
(m) Certificate : Supplier shall provide purchaser
procurement of raw materials i.e., core, insulation
Supplier shall also record a certificate as under :
details of
& copper.
" CERTIFICATE "
It is certified that the Transformer shall be manufactured by --------(Name of manufacturer) out of the core, insulating and winding
material procured as per details indicated in enclosed schedule.
We are agreeable
to undertake third party inspection of
Transformer during its manufacture or of raw materials, at the sole
discretion of MPPTCL without any extra cost.
If at any stage it is found that the transformer is not manufactured
out of the raw material indicated in enclosed Schedule, the
transformer shall be liable for rejection
by MPPTCL
and
transformer shall be replaced by (name of manufacturer) at no
extra cost to MPPTCL.
Signature of Authorised
Signatory with Seal of
manufacturer
(n)
The Purchaser also reserves the right to carry out stage
inspections at other stages also, for which advance intimation
shall be given and all necessary cooperation shall be rendered
by the supplier.
(o)
Epoxy bonded Continuously Transposed Conductor (CTC) shall be
used in main winding for rated current of 400 A or more.
(p) The conductor insulation shall be made from high-density (at
least 0.75 gm/cc) paper having high mechanical strength. Density of
paper shall be verified by paper manufacturer test certificate.
(q) The barrier insulation including spacers shall be made from highdensity pre-compressed pressboard (1.15 gm/cc minimum for load
bearing and 0.95 gm/cc minimum for non-load bearing) to minimize
dimensional changes. Kraft insulating paper used on conductor
should have density of >0.75 g/cc. To verify the parameters
manufacturer test certificate can be accepted.
(r)
Winding paper moisture shall be less than 0.5%.
11.13 A) BUSHINGS :- Bidders may please note that Transformers covered in
the bid are being procured with RIP Bushings instead of OIP Bushings,
Volume-II
24
400KV 500 MVA Transformer
however some parameters of OIP bushings are detailed below for reference
and the same shall also be applicable for RIP Bushings.
(a) The electrical & mechanical characteristics of bushings shall be
in accordance with IS-3347 & IS-2099 ( latest version ) & IEC
60137(2008 or latest version).
(b)
(c)
(d)
(e)
(f)
(g)
(h)
(i)
Volume-II
The bushings shall have high factor of safety against leakage to
ground and shall be so located as to provide adequate electrical
clearances between bushings and also between the bushings
and grounded parts. Bushings of identical voltage rating
shall be of similar BCT and inter changeable. All bushings
shall be equipped with suitable terminals of approved type and
size and all external current carrying contact surfaces shall be
adequately silver plated. The insulation class of the high voltage
neutral bushing shall be properly coordinated with the insulation
class of the neutral of the high voltage winding.
All main winding and neutral leads shall be brought out through
outdoor type bushings which shall be so located that the full
flashover strength will be utilized and the adequate phase
clearance shall be realized.
Each bushing shall be so coordinated with the transformer
insulation that all flashovers will occur outside the tank.
All porcelain used in bushings shall be of the wet process,
homogeneous and free from cavities or other flaws. The glazing
shall be uniform in color and free from blisters, burns and other
defects.
(i) For 33KV winding & neutral of common winding, the
bushing shall be of OIP condenser of 72.5KV class of draw rod
type/solid stem type.
(ii) The bushings of 420 KV & 245 KV class shall be of OIP
condenser of draw rod type (DR) only.
(iii) Tan-delta of all bushings shall be 0.005 (max.) during testing at
manufacturer’s works/site.
All bushings shall have puncture strength greater than the dry
flashover value.
Main winding terminals shall be solder-less terminals and shall be
of the type and size specified in the schedule of requirement of
drawings.
The spacing between the bushings must be adequate to prevent
flashover between phases under all conditions of operation. The
clearances shall be as follows :
25
400KV 500 MVA Transformer
S.
No
1
2
3
Impulse
Nominal Voltage
Current Withstand
System Class of
Rating
Voltage
Voltage Bushing
(Kvp)
400KV
220KV
33KV
420KV
245KV
72.5KV
1250A
2000A
3150A
1425
1050
325
1 Min. Power
Frequency/
Switching
Impulse
Voltage
Kv (Rms)
630/1050
460 / 140 / -
Creepage
Distance
in mm
10500
6125
1813
Clearance
in mm
Ph to
Ph
Ph to
E
4000
2700
700
3500
2400
660
The Tenderer s are required to confirm clearances and no change /
reduction in clearances shall be acceptable. The clearances shall be
clear distances in air after accounting for clamps/connectors
dimensions to be mounted on the stud of bushings.
(j) Special adjustable arcing horns shall be provided for the HV & IV
bushings. For 72.5KV class bushings, arcing horns are not required.
(k) The Tenderer is requested to furnish the guaranteed withstand
voltage for the above and also furnish a calibration curve with
different settings of the coordination gap to the purchaser to
decide the actual gap setting. Tenderer’s recommendations are
also invited in this respect.
(l) The bushings shall be capable of withstanding without injury the
electrical, thermal and mechanical effects of external short circuits.
Bushings shall be rated for short time thermal current rating of 63/
40/ 31.5 KA for 3 seconds, for 400/ 220/ 33 KV respectively.
(m) All the transformers covered under this specification shall be
utilized in heavily polluted atmosphere. In view of
this the
Tenderers while offering prices for the transformers against this
contract may please note that the offer should be made out based
on the creepage for the bushings @ 25mm per KV based on the
voltage of 72.5KV/245KV/ 420KV. Thus in the quoted prices of
transformer cost of bushings should be included based on a
creepage distance of 25mm per KV.
(n) All O.I.P. Condenser bushings shall be provided with :
(i) Oil level gauge.
(ii) Oil filling plug and drain valve, if not hermetically sealed.
(iii) Tap for capacitance/tan delta test.
(o) The bushings with current transformers are specified, hence the
bushings shall
be removable without disturbing the current
transformers.
(p) Porcelain used in bushing manufacture shall be homogenous, free
from laminations, cavities and other flaws or imperfections that
might affect the mechanical or dielectric quality
and shall be
thoroughly vitrified tough and impervious to moisture. Glazing of
porcelain and bushing shall be of uniform brown color free from
blisters and burrs.
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26
400KV 500 MVA Transformer
(q)
(r)
(s)
(t)
(u)
Bushing turrets shall be provided with suitable vent pipes which
shall be connected to route any air/gas collection through the
Buchholz relay.
For Bushings of all voltage class, the arrangement for
connection of winding/neutral terminal shall be indicated .
From the end point of the condenser of the bushing which will
protrude inside the transformer OR the bottom termination point
of bushing, sufficient clearance should be available so that in case
any other make bushing is installed problem in this regard may
not arise. Maximum length of condenser portion, which can be
easily accommodated, should be clearly indicated by the Tenderer.
The LV take off arrangement within the transformer is of utmost
importance hence due care shall be taken while providing this
arrangement inside the transformer tank. The connecting lug of LV
winding with the bushing bottom terminal pad should match with the
current rating of the bushing. The size of the LV winding lug shall be
of suitable rating to match with the maximum load current of the
transformer to be fed through extreme tap of OLTC meeting
requirements of IS-6600. In this regard, the clamping
arrangement of LV winding with two lugs having two holes
with two hole terminals on counter part of the bushing pad are
not acceptable. In case of such arrangement, it will have to be
ensured that the counter part of winding lead/lug i.e. bushing
terminal is with four holes or vice versa. Similar arrangement
shall be ensured for termination of neutral lead on neutral
bushing pad.
Size of turret for particular rating of bushing should be inline
with requirements specified by the bushing supplier in respect
of min dia. & lower insulation arcing distance etc.
(B) Bushings (RIP):- The transformer will procured with RIP bushings with all
the ratings indicated above:a)
b)
c)
Volume-II
Bushings shall be robust and designed for adequate cantilever strength
to meet the requirement of seismic conditions, substation layout and
movement along with the spare Transformer with bushing erected and
provided with proper support from one foundation to another foundation
within the substation area. The electrical and mechanical characteristics
of bushings shall be in accordance with IEC: 60137/DIN 42530. All
details of the bushings shall be submitted for approval and design
review.
Bushing for voltage of 72.5 kV and above shall be RIP bushings with
composite polymer insulator as per detailed indicated in cl.no. 11.10.
RIP type bushing shall be provided with tap for capacitance and tan
delta test. Test taps relying on pressure contacts against the outer earth
layer of the bushing is not acceptable.
27
400KV 500 MVA Transformer
d)
e)
f)
g)
Where current transformers are specified, the bushings shall be
removable without disturbing the current transformers.
Bushings of identical rating shall be interchangeable to optimise the
requirement of spares.
Porcelain used in bushing manufactures shall be homogenous, free from
lamination, cavities and other flaws or imperfections that might affect the
mechanical or dielectric quality and shall be thoroughly vitrified, tough
and impervious to moisture.
Polymer / composite insulator shall be seamless sheath of a silicone
rubber compound. The housing & weather sheds should have silicon
content of minimum 30% by weight. It should protect the bushing against
environmental influences, external pollution and humidity. The interface
between the housing and the core must be uniform and without voids.
The strength of the bond shall be greater than the tearing strength of the
polymer. The manufacturer shall follow non-destructive technique
(N.D.T.) to check the quality of jointing of the housing interface with the
core. The technique being followed with detailed procedure and
sampling shall be finalized during finalization of drawings.
The weather sheds of the insulators shall be of alternate shed
profile as per IEC 60815-3. The weather sheds shall be vulcanized to
the sheath (extrusion process) or moulded as part of the sheath
(injection moulding process) and free from imperfections. The
vulcanization for extrusion process shall be at high temperature and for
injection moulding shall be at high temperature & high pressure. Any
seams / burrs protruding axially along the insulator, resulting from the
injection moulding process shall be removed completely without causing
any damage to the housing. The track resistance of housing and shed
material shall be class 1A4.5 according to IEC60587. The strength of the
weather shed to sheath interface shall be greater than the tearing
strength of the polymer. The composite insulator shall be capable of
high pressure washing.
h)
i)
j)
Volume-II
End fitting shall be free from cracks, seams shrinks, air holes
and rough edges. End fittings should be effectively, sealed to prevent
moisture ingress, effectiveness of sealing system must be supported by
test documents. All surfaces of the metal parts shall be perfectly smooth
with the projecting points or irregularities which may cause corona. All
load bearing surfaces shall be smooth and uniform so as to distribute
the loading stresses uniformly.
The hollow silicone composite insulators shall comply with
requirements of the IEC publications IEC 61462 and the relevant parts
of IEC 62217. The design of the composite insulators shall be tested
and verified according to IEC 61462 (Type & Routine test)
Clamps and fittings shall be of hot dip galvanised/stainless steel.
Bushing turrets shall be provided with vent pipes, to route any gas
collection through the Buchholz relay.
No arcing horns shall be provided on the bushings.
28
400KV 500 MVA Transformer
k)
l)
m)
n)
o)
p)
RIP Bushing shall be specially packed to avoid any damage during
transit and suitable for long storage, with non-returnable packing
wooden boxed with hinged type cover. Without any gap between
wooden planks. Packing Box opening cover with nails/screws type
packing arrangements shall not be acceptable. Bushing oil end portion
shall be fitted with metal housing with positive dry air pressure and a
suitable pressure monitoring device shall be fitted on the metal housing
during storage to avoid direct contract with moisture with epoxy.
Alternatively, oil filled metal housing with suitable arrangement for taking
care oil expansion due to temperature variations shall be also be
acceptable. Manufacturer shall submit drawings / documents of packing
for approval during detail engineering. Detail method for storage of
bushing including accessories shall be brought out in the instruction
manual. Adequate precautions must also be taken to ensure that the
storage of RIP bushing with polymer housing, which is susceptible to
attacks by rodents or birds, is done in a rodent/pest-free environment by
using PVC coated mesh or any other material for wrapping. Bushings
which are kept in storage container can be used even after long term
storage without any further testing of the bushing.
The terminal making and their physical position shall be as per
IEC:60076.
The delta measurement at variable frequency (in the range of 20 Hz to
350 Hz) shall be carried out on each condenser type bushing (OIP &
RIP) at Transformer manufacturing works as routine test before
despatch and the result shall be compared at site during commissioning
to verify the healthiness of the bushing.
If the bushing Tan delta goes beyond 0.005 or increase is more than
0.001 within the warrantee period w.r.t. per-commissioning values, the
contractor shall arrange to replace the defective bushing by new one. No
temperature correction factor shall be applicable for tan delta.
Tan delta measurement at variable frequency (in the range of 20 Hz to
350 Hz) shall be carried out on each condenser type bushing (OIP &
RIP/ RIS) at Transformer manufacturing works as routine test before
despatch and the result shall be compared at site during commissioning
to verify the healthiness of the bushing.
Tan δ value of OIP/RIP/RIS condenser bushing shall be 0.005 (max.)
in the temperature range of 10°C to 40°C. If tan delta is measured at a
temperature beyond above mentioned limit, necessary correction factor
as per IEEE shall be applicable.
Note:- Bidders may please note that RIP Bushings manufactured in India shall be
considered subject to approval.
11.14 Bushing Current Transformers:(a) Current transformers shall comply with IS:2705.
(b) One no. bushing CT of Ratio 1000-2000/1-1 on each phase of HV &
IV winding i.e 3 nos. for HV & 3 nos. for IV winding, one no. outdoor
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400KV 500 MVA Transformer
(c)
(d)
(e)
bushing CT of Ratio 1000-2000/1-1 for neutral shall be provided for
each Transformer.
Further, one no. 33 KV bushing CT of Ratio 1600/1-1 shall be
supplied as per clause no.9.7.3. In addition to above, also three nos.
33 KV bushing CT of ratio 1600/1 shall be provided for each phase.
It shall be possible to remove turret mounted CTs from the
transformer tank without removing the tank cover. Necessary
precaution shall be taken to minimize the eddy currents and local
heat generated in the turret.
All secondary leads shall be brought to a terminal box near each
bushing. These terminals shall be wired out to cooler control cabinet
using separate cables for each core.
For the thermal image coil of winding temperature indicator, ‘CT’
with suitable ratio and class may be used.
11.15 Terminal Marking : The terminal marking and their physical position shall be
in accordance with IS:2026.
11.16 The positioning of HV & IV bushings shall be such that skew jumpering is
avoided. The middle phase primary & secondary bushing center line shall be parallel
to side axis of the transformer body.
12.0
EARTHING ARRANGEMENT :
12.1 NEUTRAL EARTHING ARRANGEMENT : The neutral terminal of the star
connected HV / IV winding shall be brought up to the ground level through two
tinned copper flat strips of size 75x12mm which shall be supported on transformer
tank horizontal/vertical by porcelain insulators of 36 KV voltage class. The number
of insulators shall be sufficient to provide a mechanically sturdy arrangement.
Necessary mechanical supports on the tank for mounting of the insulators shall be
made. It may be ensured that connection of the neutral strips to neutral bushings at
one end shall be made using a terminal connector suitable for connection to the
neutral bushing terminal and to receive 2x75x12mm tinned copper strips on the
other side. The connection between the bushing and transformer’s earth pit shall be
through 2x75x12mm tinned copper strips single run without any joint
connection/brazing/ welding etc. In case of problem in availability of single run tinned
copper strips, it may be accepted with single joint. However, joint to be provided
shall be subject to approval of purchaser. The other end of the earth connection to
the earth pit shall also be through terminal connector suitable to receive 2x75x12mm
copper strips at one end and to receive MS flat and /or twin ACSR Moose conductor
on the other end. The length of the copper strips shall be suitable for providing a
joint less connection between transformer neutral and earth pit and details in this
regard shall be intimated to the successful Tenderer based on
transformer/substation layout design. A typical arrangement is shown in drg. No:
MPPTCL/500MVA/02 of this specification for neutral earthing.
12.2 CORE EARTHING ARRANGEMENT: The Tenderer should note our
requirement in this regard very clearly. It is required to bring out leads from core,
end frame and tank to the top of the transformer through only three insulated
bushings. These Bushings shall be non oil communicating type of minimum 17.5 KV
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30
400KV 500 MVA Transformer
class Porcelain Bushings. The arrangement shall be housed in a box at the top cover
of transformer tank with provision for interconnection between the studs of bushings.
The bushing housing shall have a suitable cover with gasket to make the
arrangement waterproof. A clear marking (engraved/punched) shall be made to
indicate that the housing contains core/end frame/ tank earthing arrangement.
Please note that stickers/flags/tags/painted marking for identification shall not
be accepted. A typical sketch of general arrangement needed by purchaser is
shown in drawing no. MPPTCL/500MVA/03 of this specification. Arrangement shall
be such that even after removal of connections, oil shall not leak. Removable
shorting strips between the three bushing shall be provided. It may be noted that
internal earthing of any nature between core and End frame should not be
provided. Earthing at site shall be done by interconnecting the three bushings
through shorting strips. This arrangement is to facilitate checking of multiple core
earthing in the transformer.
It may be noted that :
a) Any alternative arrangement is not acceptable and therefore
Tenderer must confirm provision of three bushings as desired
above.
b) Once transformer reaches site, before unloading from the trailer the
position of core earthing shall be checked and in case any problem
of multiple core earthing is observed, delivery of Transformer will not
be taken.
The insulated cable to be used for core to Bushing connection & end frame to
Bushing connection should be of good quality with proper grounding
arrangement. The size and number of strands of cable shall be subject to
purchaser’s approval.
13.0
AUXILIARY POWER SUPPLY FOR OLTC, COOLER CONTROL
POWER CIRCUIT
AND
13.1 Duplicate(Two) auxiliary power supplies of 0.415 KV, three phase, four(4)
wire shall be provided by the purchaser at cooler control cabinet and for OLTC
drive.
13.2 All loads shall be fed by one of the two feeders through an electrically
interlocked automatic transfer switch housed in the cooler control cabinet , for tap
changer control and cooler control circuits.
13.3
Design features of the transfer switch shall include the following :
i)
Provision for the selection of one of the feeders as normal source
and other as standby.
ii)
Upon failure of the normal source, the loads shall be
automatically transferred after an adjustable time delay to the
standby source.
iii) Indication to be provided at cooler control cabinet for failure of
normal source and for transfer to standby source and also for failure
to transfer.
Volume-II
31
400KV 500 MVA Transformer
iv)
v)
Automatic re-transfers to normal source without any intentional
time delay following re-energisation on the normal source.
Both the transfer & re-transfer shall be dead transfers and AC
feeders shall not be paralleled at any time.
13.4 AC feeder shall be brought to the OLTC cabinet (Cooler Control Cabinet) by
the Tenderer, after suitable selection at cooler control cabinet. The Tenderer shall
derive AC power for control circuit from the AC feeder as mentioned above by
using appropriately rated dry type transformers. If the control circuit is operated
by DC supply then suitable converters to be provided by the Tenderer to be
operated from AC Power source.
13.5 Necessary isolating switches and HRC fuses shall be provided at suitable
points as per approved scheme of purchaser.
14.0
TAP CHANGING EQUIPMENT :
14.1
General Requirement
(a) OLTC gear shall be motor operated for local as well as remote
operation. An external hand wheel/handle shall be provided for
local manual operation. This hand wheel/handle shall be easily
operable by a man standing at ground level.
(b) Arrangement shall be made for securing and padlocking the tap
changer wheel in any of the working positions and it shall not be
possible for setting or padlocking the wheel in any intermediate
position. The arrangement shall be such that no padlock key can
be inserted unless all contacts are correctly engaged and switch set
in a position where no open or short circuit is possible. An indicating
device shall be provided to show the tap in use.
(c) The current & voltage rating of OLTC for the transformers shall
be as under. The through current rating of OLTC shall be based
on Clause 2.3.2 of IS 8478 and following OLTC rating specified are
the minimum requirements.
Tenderer, however must offer
bidirectional OLTC of linier type with higher current rating, as
mentioned below:Rating of OLTC
OLTC on
Transformer
Winding Voltage
Minimum
Tap Range
Rating
(IV)
Rating Current rating (In steps of 1.25%)
500MVA,
1800/
-10 % to +10% of
220KV (IV) 245KV
400/220/33 KV
2100Amp
220kV
(d)
The OLTC motor should be capable of smooth and trouble free
operation with supply voltage variation of 0.415KV -25% & +10%.
The OLTC having bidirectional flow of power of linear type shall be
preferred.
(e) The design of the tap changing arrangement shall be such that there
should be minimum variation of ohmic impedance of the transformer
Volume-II
32
400KV 500 MVA Transformer
from minimum to maximum tap. The permissible tolerance on these
ohmic values shall be plus minus 10%.
14.2
On Load Tap Changing Gear (OLTC):
(a) The details of the method of diversion of the load current during tap
changing, the mechanical construction of the gear and the control
features for OLTC gear alongwith detailed drawings on the inner
view and the arrangement of connections shall be submitted with
the Tender. Information regarding the service experience on the
gear and a list of important users shall also be furnished. The tap
changer shall change the effective transformation ratio without
producing phase displacement.
(b) The current diverting contacts shall be housed in a separate oil
chamber not communicating with the oil in main tank of the
transformer.
(c) The contacts shall be accessible for inspection without lowering
oil level in the main tank and the contact tips shall be replaceable.
(d) The Tenderer shall indicate the safeguards employed to take care of
harmful arcing at the current diverting contacts in the event of
operation of the OLTC gear under overload conditions
(overloading capability as per IS 6600) of the transformer.
Necessary tools and tackles shall be provided alongwith main
supply for maintenance of OLTC gear.
(e) The OLTC oil chamber shall have oil filling and drain valves, oil
sampling valve, relief vent and oil level gauge/glass. It shall also
be fitted with an oil surge relay. For accommodating oil expansion of
OLTC a separate conservator tank shall be provided.
(f) The diverter switch or arcing switch shall be designed so as to
ensure that its operation once commenced shall be completed
independently of the control relays or switches, failure of auxiliary
supplies etc. To meet any contingency which may result in
incomplete operation of the diverter switch, adequate means shall
be provided to safeguard the transformer and its ancillary
equipments.
(g) Drive mechanism chamber shall be mounted on the tank in
accessible position. It should be adequately ventilated and provided
with anti condensation metal clad heaters. All contactors, relay coils
and other parts shall be protected against corrosion, deterioration
due to condensation, fungi etc.
(h) The control feature shall provide the following :
i)
LOCAL-REMOTE selector switch mounted in the local
control cubicle shall switch control of OLTC for lower/ raise
functions in local or remote mode as selected.
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33
400KV 500 MVA Transformer
The LOCAL-REMOTE selector switch shall have at-least two
spare contacts per position which are closed in that position
but open in the other position.
iii) A RAISE-LOWER CONTROL SWITCH shall be provided in
the local control cubicle. The switch shall be spring loaded to
return to the Centre "OFF" position and shall require movement
to the RIGHT to raise the voltage of the transformer.
Movement to the left shall lower the voltage. Alternatively
push button type arrangement of standard design may be
provided.
iv) An OFF-ON tap changer control switch shall be provided in
the OLTC local control cabinet of transformer. The tap
changer shall be inoperative in the OFF position. Also the
OFF-ON switch shall have atleast one spare contact per
position which is closed in that position but open in the other
position.
v)
Operating mechanism for on load tap changer shall be
designed to go through one step or tap change per
command. Subsequent tap changes shall be initiated only by a
new or a repeat command.
vi) On load tap changer shall be equipped with a time delay in
complete STEP alarm consisting of a normally open contact
which closes, if the tap changer fails to make a complete tap
change. The alarm shall not operate for momentary loss of
auxiliary power.
vii) The selsyn units or approved equivalents shall be installed
in the local OLTC control cabinet to provide tap position
indication for the transformer. Complete mounting details
shall be included with approved diagram.
viii) Transformer load tap changer shall be equipped with a fixed
resistor network capable of providing discrete voltage steps
for input to the supervisory system. Any other approved /
established design for remote indication of tap position shall
also be acceptable.
Limit switches shall be provided to prevent over-running of the
mechanism and in addition, a mechanical stop shall be provided to
prevent over-running of the mechanism under any condition.
Limit switches may be connected in the control circuit of the
operating motor provided that a mechanical-de-clutching mechanism
is incorporated.
Thermal device or other means shall be provided to protect the
motor and control circuit. All relays, switches, fuses etc. shall be
mounted in the drive mechanism chamber and shall be clearly
marked for the purpose of identification.
ii)
(i)
(j)
(k)
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34
400KV 500 MVA Transformer
(l)
A permanently legible lubrication chart shall be fitted within the
driving mechanism chamber.
(m) Any "DROP DOWN" tank associated with the tap changing
apparatus shall be fitted with guide rod to control the movements
during lifting or lowering.
(n) A five digit counter shall be fitted to the tap changing equipment to
indicate the number of operations performed.
(o) All relays and operating devices shall operate correctly at any
voltage between the limits specified.
(p) It shall not be possible to operate the electric drive when the manual
operating gear is in use.
(q) It shall not be possible for any two controls to be in operation at
the same time.
(r) The equipment shall be suitable for supervisory control and
indication with make before break multi-way switch, having one
potential free contact for each tap position. This switch shall be
provided in addition to any other switch/switches which may be
required for remote tap position.
(s) Operation from the local or remote control switch shall cause
one tap movement only until the control switch is returned to the
off position between successive operations.
(t) All electrical control switches and the local operating gear shall be
clearly labeled in a suitable manner to indicate the direction of tap
changing.
(u) Transfer of source failure of one AC supply shall not affect tap
changing operation.
(v) For the purpose of operation of OLTC, based on design of
manufacturer, transition resistor could be used. However, no
component of OLTC including transition resistor shall be housed
inside main transformer tank. The design of the transition resisters
should be liberal to ensure suitability during tap change operation at
rated current including over loading capability and system short
circuits.
(w) The location and design of OLTC shall be such that in the event of
any repair / maintenance , it should be possible to take out various
parts from the OLTC and other accessories and fittings mounted on
the transformer particularly equalizing pipes etc do not infringe /
obstruct.
14.3 Manual Control: The cranking device for manual operation of the OLTC gear
shall be removable and suitable for operation by a man standing on ground level.
The mechanism shall be complete with the following :
i)
Mechanical tap position indicator which shall be clearly visible to
the person operating tap changer manually at the transformer.
ii)
A mechanical operation counter.
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35
400KV 500 MVA Transformer
iii)
iv)
Mechanical stoppers to prevent over-cranking of the mechanism
beyond the extreme tap positions.
The manual control considered as back up to the motor
operated load tap changer control shall be interlocked with the
motor to block motor start-up during manual operation. The manual
operating mechanism shall be labeled to show the direction of
operation for raising the voltage and vice-versa.
14.4 Electrical Control : This includes Local Electrical control and Electrical
remote control from remote control panel. The control circuits shall have the
following features:
i.
An interlock to cut off electrical control automatically upon
recourse being taken to the manual control in emergency.
ii.
Reinforcement of the initiating impulse for a tap change, ensuring
a positive completion once initiated to the next (higher or lower)
tap.
iii.
Step-by-step operation ensuring only one tap change from each
tap changing impulse and lock-out of the mechanism if the control
switch (or push button) remains in the "Operate Position".
iv.
An interlock to cut-out electrical control when it tends to operate the
gear beyond either of the extreme tap positions.
v.
An electrical interlock to cut-off a counter impulse for reverse step
change being initiated during a progressing tap change and until
the mechanism comes to rest and resets circuits for a fresh
position. Suitable interlocks shall be provided to prevent operation
of OLTC beyond extreme tap with a mechanical/electrical lockable
switch.
vi.
Protection apparatus, considered essential by the Tenderer
according to specification.
14.5 Remote Electrical Group Control : The OLTC control scheme offered
shall have provision of remote electrical group control during parallel operation of
transformers. This is in addition to independent control of OLTC.
i.
A four position selector switch having MASTER, FOLLOWER,
INDEPENDENT and OFF position shall be provided in the remote
OLTC control panel for each transformers. This shall be wired to
enable operator to select operation of OLTC in either Master,
Follower or Independent mode.
ii. Out of step relays with timer contacts shall also be provided to
give alarm and indication in case of tap positions in all the
transformers under group control being not in same position.
iii. Master Position : If the selector switch is in MASTER position,
it shall be possible to control the OLTC units in the FOLLOWER
mode by operating the controls of the MASTER unit Independent
operation of the units under FOLLOWER mode shall have to be
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36
400KV 500 MVA Transformer
prevented. However, the units under independent mode will be
controlled independently.
iv. Follower Position : If the selector switch is in FOLLOWER mode,
control of OLTC shall be possible only from MASTER panel.
v. Independent Position : In this position of Selector Switch, Control
of OLTC of individual unit only shall be possible.
14.6 Local OLTC Control Cubicle : The Auxiliary devices for electrical control
of the OLTC shall be housed in a weather proof cubicle . It shall be complete with
the following :
i)
A circuit breaker/contactor with thermal overload devices for
controlling the AC auxiliary supply to the OLTC motor.
ii)
Cubicle light with door switch.
iii) Space heaters to prevent condensation of moisture.
iv) Padlocking arrangement for hinged door of cabinet.
v) Cable terminal glands for power and control cables to the OLTC
gear.
14.7
Digital RTCC Panel:-
14.7.1.
The digital RTCC relay shall have automatic Tap Changer control and
monitoring relay with Automatic Voltage Regulating features (referred as
Digital RTCC relay) to remotely control and monitor OLTC.
For new substation the contractors shall provide digital RTCC panel
consisting of 4 Nos. Digital RTCC relays. Further, one spare digital RTCC
relay shall also be provided in the same panel. Each digital ETCC relay
shall be used to control 1 bank of transformers (i.e. 3 Nos. I-Phase units or
1 No. 3-Phase unit). For existing substations, the requirement of digital
RTCC panel and relays are specified in Section-Project /BPS. However,
bidders are advised to get clarified about the availability of existing RTCC
schemes/Digital RTCC relays to finalise matching digital RTCC relays
requirements. The digital RTCC relays envisaged for existing transformers
shall be integrated for parallel operations. All required cables for the same
shall be included in the scope.
Digital RTCC relay shall be microprocessor based adopting the latest state
of the art design & technology with in-built large display for ease of
programming and viewing. The unit supplied shall be field programmable
so that in the event of change in transformer/location, it could be
customized to site conditions without sending back to works. The
programming shall be menu driven and easily configurable. If it is
designed with draw out type modules, it should take care of shorting all CT
inputs automatically while drawing out. The CT/VT ratio shall be filed
programmable and relay shall display the actual HV voltage and current
considering suitable multiplying factors. The system shall be self-sufficient
and shall not require any additional devices like parallel balancing module
etc. All digital RTCC relays shall be of same make for smooth integration
14.7.2.
14.7.3.
Volume-II
37
400KV 500 MVA Transformer
14.7.4.
14.7.5.
14.7.6.
14.7.7.
of these relays for parallel operations of all transformers in the substation.
Further specification are as per Annexure-I.
The RTCC panel shall be provided with digital RTCC relay having
raise/lower push buttons, manual/automatic mode selection features.
Master/follower/Independent /Off mode selection features for control of
OLTC. Touch screen option in the relay instead of electrical push
button/switch is also acceptable.
In Manual Mode: In his mode, power system voltage based automatic
control from digital RTCC relay shall be blocked and commands shall be
executed manually by raise/lower push buttons.
In Auto Mode: In auto mode, digital RTCC relay shall automatically control
OLTC taps based on power system voltage and voltage set points. An
interlock shall be provided to cut off electrical control automatically upon
recourse being taken to the manual control on emergency.
Master/follower/Independent /Off mode: Master/follower parallel operation is
required with group simultaneous feature in digital RTCC relay. Master
follower scheme implies that controlled decision shall be taken by the
master and control actions (Raise/Lower tap position) shall be executed
simultaneously by master & follower units. Same logic needs to be
implemented in digital RTCC relays.
Master Position: If the digital RTCC relay is in master position, it shall be
possible to control the OLTC units of other parallel operating transformers
in the follower mode by operation from the master unit.
Follower Position: If the digital RTCC relay is in follower position, control
of OLTC shall be possible only from panel where master mode is selected.
14.7.8.
14.7.9.
Independent Position: In Independent Position of selector switch, control
of OLTC shall be possible only from the panel where independent mode is
selected.
Suitable interlock arrangement shall be provided to avoid
unwanted/inconsistent operation of OLTC of the transformer.
Raise/Lower Control: The remote OLTC scheme offered shall have
provision to raise or lower taps for the complete bank of three I-phase
transformers / 3-Phase transformers. Individual I-phase OLTC operation
shall not be possible from the remote control panel.
Digital RTCC relays shall communicate with SCADA using IEC 61850
through FO port to monitor, parameterise & control the OLTC. Any
software required for this purpose shall be supplied. The supplied software
shall not have restriction in loading on multiple computers for downloading
and analysing the data. Software shall indicate the current overview of all
measured parameters of the connected transformer in real time. The digital
RTCC relay shall have multiple selectable set point voltages and it shall be
possible to select these set points from SCADA, with a facility to have the
possibility of additional set points command from SCADA.
Communication between the digital RTCC relays to execute the commands
for parallel operation shall be implemented using required communication
Volume-II
38
400KV 500 MVA Transformer
protocol. IEC-61850GOOSE messaging between digital RTCC relays for
OLTC parallel operation is not permitted.
Suitable communication
hardware shall be provided to communicate up to distance of 1km between
digital RTCC relays. Scope shall also include communication cables
between digital RTCC relays. Cables as required for parallel operation of
OLTCs of all transformers (including existing transformers wherever
required) from digital RTCC relays shall be considered included in the
scope of bidder.
14.7.10
14.7.11.
14.7.12.
The digital RTCC relay shall have additional programmable Binary Input
(minimum 7Nos.) and Binary output (minimum 7Nos.) for Employer’s future
use. It shall be possible to have additional module for Binary Input/output
as well as Analogue input module depending upon requirement.
The relay shall ensure positive completion of lowering/raising of the OLTC
tap, once the command is issued from the relay. “Step-by-Step” operation
shall be ensured so that only one tap change from each tap changing pulse
shall be effected. It the command remains in the operate “position, lockout of the mechanism is to be ensured.
Following minimum indications/alarms shall be provided in digital RTCC
relay either through relay display panel or through relay LEDs.
a.
b.
c.
d.
e.
f.
g.
h.
INCOMPLETE STEP alarm
OLTC motor overload protection alarm
Supply to DM Motor fail alarm
OLTC IN PROGRESS alarm
Local/Remote Selector switch positions in DM Box
OLTC upper/lower limits reached alarm
OLTC tap position indications for transformer units.
Independent-combined-remote selector switch positions of CMB (In case of
single phase transformer)
i. 415V, AC Main Supply Fail
j. 415V, AC standby Supply Fail
14.7.13.
15.0
In case of parallel operation or I-Phase transformer unit banks, OLTC out
of step alarm shall be generated in the digital RTCC relay for discrepancy
in the tap position.
COOLING EQUIPMENT
15.1
Volume-II
The design shall take into account the following requirements
a) The oil cooling system of transformer shall be designed using
2x50% radiator banks. The radiator banks shall preferably be
mounted on two different sides of
transformer tank. The
arrangement shall be subject to approval by the purchaser based on
substation layout and positioning of other neighboring switch yard
equipments. Coolers/radiators shall withstand pressure / vacuum
conditions specified for the tank. All coolers/ radiators shall be
attached on the transformer tank through header having suitable
expansion joints (flexible coupling) to ensure adequate
39
400KV 500 MVA Transformer
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
Volume-II
mechanical strength against vibration etc. subject to specific
approval from the purchaser. Radiators directly mounted on
transformer tank are not acceptable.
Each radiator bank / block shall have its own set of cooling fans,
shut off valves, lifting lugs, top and bottom oil filling valves, air
release plugs, drain valves and if considered necessary based
on design thermometer pocket fitted with captive screw cap on the
inlet and outlet, in line with valve schedule as per Annexure-V.
Each radiator bank shall be provided with at least 20% standby
(spare)cooling fans. These spare fans shall be duly mounted and
shall also be wired up complete with required protective devices
and be identified with each radiator bank. While working out
number of spare fan for 20% additional cooling per bank, if 20%
quantity works out in fraction , the spare fans to be provided shall be
next whole number. Cooling fans shall be designed to meet
overloading requirements as per clause 4.1 (b).
Two (2), 100% centrifugal oil pumps (out of which one pump shall be
standby) shall be provided with each radiator bank. Measures shall
be taken to prevent mal-operation of Buchholz relay when all oil
pumps are simultaneously put into service. The pump shall be so
designed that upon failure of power supply to the pump motor, the
pump impeller will not limit the natural circulation of oil. Under failure
of main oil pump, the changeover from main to standby oil pump
shall be automatic.
Cooling fans and oil pump motors shall be suitable for operation
from 0.415KV, three phase 50 HZ power supply and shall conform to
IS:325.
An oil flow indicator shall be provided for the confirmation of the oil
pump operating in a normal state. A provision shall be made in the
flow indicator to indicate reserve flow of oil/loss of oil flow.
The exhaust air flow from cooling fan shall not be directed towards
the main tank in any case. Cooling fans for each radiator bank shall
be located so as to prevent ingress of rain water. Each fan shall be
suitably protected by galvanised wire guard.
The cooler and its accessories shall preferably be hot dipped
galvanised or corrosion resistant paint shall be applied to it.
Each cooling fan shall be provided with starter thermal overload
and short circuit protection and also single phase preventor.
Each radiator shall be provided with suitable lifting lugs and shut
off/air release/sampling valves as per Annexure-V. The sheet
thickness of radiator tube shall be of minimum 1.2 mm.
Expansion joints, one each on top and bottom cooler pipe
connections as per ‘a’ above.
Air release device/plug and oil drain plug on oil pipe connections.
40
400KV 500 MVA Transformer
m)
n)
o)
p)
The cooling Fans shall be mounted on separate foundation.
Mounting of Cooling fans directly on Radiators or on
transformer tank is not acceptable .
Cooling fan support shall be of adequate strength to avoid bending
etc.
The mounting arrangement of cooling fans shall be subject to
drawing approval from MPPTCL.
Cooling fans and oil pump motors shall be suitable for operation from
415 volts, three phase 50 Hz power supply and shall be of premium
efficiency class IE3 conforming to IS: 12615. Each cooling fan and
oil pump motors shall be provided with starter, thermal overload and
short circuit protection. The motor winding insulation shall be
conventional class 'B' type. Motors shall have hose proof enclosure
equivalent to IP: 55 as per IS/IEC 60034-5.
15.2
Cooling Equipment Control (ONAN/ONAF/OFAF Cooling)
a) Automatic operation control (switching in and out) of fans shall be
provided (with temperature change) from contacts of winding
temperature indicator. The TENDERER shall recommend the
setting of WTI for automatic changeover of cooler control from
ONAN to ONAF and ONAF to OFAF. The setting shall be such that
hunting i.e. frequent start stop operations for small temperature
difference do not occur.
b) Suitable manual control facility for cooler fans & oil pumps shall be
provided.
c) Selector switches and push buttons, shall also be provided in the
cooler control to disconnect the automatic control and start/stop the
fans manually.
15.3
Indicating devices
Fan ‘ON’ , Fan ‘OFF’
Pump 'ON' and pump 'OFF'.
Cooling system ‘on automatic control’.
Cooling system ‘on manual’.
No flow/Reverse flow of oil in oil pump.
Selector switch in auto or manual for cooler and pump.
A.C. auxiliary cooler supply auto change over.
Cooler supply failure for main /standby.
Cooling fan failure for each fan.
Control supply failure for main and standby.
Oil pump failure for main and standby.
One potential free initiating contact for all the above indications shall
be wired independently to the terminal block of cooler control cabinet exclusively for
purchaser’s use.
16.0
LOCAL OLTC CONTROL CABINET, COOLER CONTROL CABINET &
REMOTE TAP CHANGER CONTROL PANEL
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41
400KV 500 MVA Transformer
a)
b)
c)
d)
e)
f)
Volume-II
Each three phase transformer unit shall be provided with local
OLTC control cabinet, cooler control cabinet OR fan control
cubicle (FCC) and RTCC panel. The total height of RTCC panel
shall be 2250mm to match with the height of other control & relay
panels. Local OLTC control cabinet shall be mounted on the
transformer. The thickness of front panel, door frame etc. shall be
3mm (10 SWG),while doors & side panels may be 2 mm (14
SWG) and gland plate shall be of minimum thickness 4mm.
The cooler control cabinet or FCC shall not be mounted directly
on transformer tank .Please note that FCC shall be grouted away
from the main tank thus the length of capillary tubes of all oil and
winding temperature indicating meter shall
be sufficient to
connect OTI and WTI meters in the FCC. The cooler cabinet shall
have all necessary devices meant for cooler control and local
temp. indicators. All the contacts of various protective devices
mounted on the transformer shall also be wired up to the
terminal Board in the cooler control cabinet. All the secondary
terminals of the bushing CT's shall also be wired upto the terminal
Board at the cooler control cabinet.
The cooler control cabinet shall have two (2) sections. One section
shall have the control equipment exclusively meant for cooler
control. The other section shall house the temperature indicators,
aux. CT's and the terminal Boards meant for termination of various
alarm and trip contacts. Alternatively the two sections may be
provided as two separate panels depending on the standard
practices of the Tenderer.
The cooler control cabinet, Local OLTC cabinet and RTCC Panel
shall be provided with non disconnecting stud type terminal
blocks. Each of the terminal blocks in the above panels should
have 20% spare terminals exclusively for purchaser’s use. All
the necessary terminals for remote connection to purchaser’s
panel shall be wired upto the cooler control cabinet. Necessary
shorting of terminals shall be done at the cooler control cabinet,
local OLTC cabinet and remote OLTC panel. All the CT secondary
terminals in the cooler control cabinet shall have provision for
short circuiting to avoid CT open circuit while it is not in use.
The local OLTC control cabinet shall house all necessary devices
meant for OLTC control and indication.
Following cabling are specifically excluded from the scope of the
Tenderer. However, interconnection drawings for the same are to
be submitted by the Tenderer.
i) Cabling between Remote OLTC Panel to Cooler Control
Cabinet.
ii) Cabling between Remote OLTC panel to Local OLTC Cabinet.
iii) Cabling between Remote OLTC to Purchaser's Panel.
iv) Cabling between Cooler Control Cabinet to Purchaser's Panel.
42
400KV 500 MVA Transformer
v)
16.1 The degree
(Category-I).
Cabling between Local OLTC Cabinet to Purchaser's Panel.
of protection shall be IP-55 in accordance with
IS-2147
16.2 The temperature indicators shall be so mounted that the dials are not
above 1600mm from ground level. Glazed door of suitable size shall be provided for
convenience of reading.
16.3
A space heater and cubicle lighting with ON-OFF switch shall be provided.
16.4
Terminal Blocks
a) The terminal blocks to be provided shall be fully enclosed with
removable covers and made of moulded, non inflammable plastic
material with block and barriers moulded integrally .Such block shall
have washer and binding screws for external circuit wire
connections, a white marking strip for circuit identification and
moulded plastic cover. All terminals shall be clearly marked with
identification numbers or letters to facilitate connection to external
wiring.
b) All internal wiring to be connected to the external equipment shall
terminate on terminal blocks, preferably vertically mounted on the
side of each panel. The terminal blocks shall be 1100 V grade
and have 10 amps continuous rating, moulded piece, complete
with insulated barriers, non-disconnecting stud type terminals,
washers, nuts and lock nuts. Terminal block design shall include a
white fiber marking strip with clear plastic, slip-on/clip-on terminal
cover. Markings on the terminal strips shall correspond to wire
number and terminal numbers on the wiring diagrams.
c) Terminal blocks for current transformer secondary leads shall be
provided with test links and isolating facilities. Also current
transformer secondary leads shall be provided with short circuiting
and earthing facilities.
d) Unless otherwise specified, terminal blocks and wiring shall be
suitable for connecting the following conductors on each side.
For all circuits except current transformer circuits minimum of two
nos. 2.5 mm2 copper.
For all CT circuits minimum of four nos. 4.0 mm2 copper.
e) There shall be a minimum edge to edge clearance of 250 mm
between the first row of terminal blocks and the associated cable
gland plate. Also the clearance between two rows of terminal
blocks shall be a minimum of 150 mm.
f)
Arrangement of the terminal block assemblies and the wiring
channel within the enclosure shall be such that a row of terminal
blocks is run parallel and in close proximity along each side of the
wiring duct to provide for convenient attachment of internal panel
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43
400KV 500 MVA Transformer
g)
wiring. The side of the terminal block opposite the wiring duct
shall be reserved for the owner's external cable connection. All
adjacent terminal blocks shall also share this field wiring corridor. A
steel strip shall be connected between adjacent terminal block rows
at 450mm intervals for support of incoming cables. Spare cable
trays are to be provided to accommodate securely supported
interconnection of cables from purchase’s panel to RTCC panel.
The number and sizes of the owner's multi core incoming cable
will be furnished to the successful Tenderer.
16.5 One Cooler Control Cabinet and OLTC local control cabinet shall be
tested for IP-55 protection in accordance with IS-2147(Category-I).
16.6
The gaskets shall be of neoprene rubber.
16.7 MOTORS : Motors shall be "Squirrel Cage" three phase induction motors of
sufficient size capable of satisfactory operation for the application and duty as
required for the driven equipment.
16.8
STATOR:
a) Stator Frame : The stator laminations shall be made from suitably
annealed to eliminate any residual stresses introduced during the
process of fabrication of machining.
b) Stator Core: The stator laminations shall be made from suitable
grade magnetic sheet steel varnished on both sides. They shall be
pressed and clamped adequately to reduce the core and teeth
vibrations to minimum.
c) Insulation and winding:
i) insulation shall be conventional class B type. The winding shall
be suitable for successful operation in hot, humid and tropical
climate with the ambient temperature of 50 deg. C. The
insulation shall be given fungicidal and tropical treatment as per
IS:3202.
ii) Any joints in the motor insulation such as coil connection or
between slot and winding section shall have strength equivalent
to that of slot section of the coil.
iii) For 0.4 KV all insulated winding conductor shall be of copper.
The overall motor winding motors, after the coil are placed in
slots and all connections are made, entire motor assembly shall
be impregnated by completely sub-merging core and winding in
suitable insulating compound or varnish followed by proper
backing. At least two additional submersion and bakes shall be
applied either making a total of at least three submersion and
bake treatment.
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44
400KV 500 MVA Transformer
16.9
ROTOR:
a) Rotors shall be adequately designed to avoid overheating during
the starting and running conditions.
b) Rotors shall be properly balanced so as to keep the vibration under
running condition within the limits.
c) Rotors of induction motors shall be of rigid core construction with
bars firmly secured and solidly bonded to the end rings. The end
rings assembly shall be such that it is free to move with expansion
of the bars without distortion. The connection of the bars to the end
ring shall be made by brazing or fusion welding.
d) Rotors shall be designed as to keep the combined critical speed
with the driven equipment away from the running speed by at least
20%.
e) Rotors shall also be designed to withstand 120% of the rated speed
for 2 minutes in either direction of rotation.
f) All high speed rotors shall be constructed with provision of rebalancing the rotor on its site position without major disassembly.
16.10
BEARING:
a) Depending upon the capacity and loading conditions supplier shall
design suitable grease lubricated or oil lubricated bearings.
b) Greased ball and roller bearings when used shall be of reputed
make subject to Purchaser's approval. The minimum standard life
of the bearings shall not be less than 30,000 working hours taking
all motors and driven loads into account. These shall be pressure
grease gun lubricated type fitted with grease nipple and shall have
grease relief devices.
c) Bearing shall be so constructed that the loss of grease and its
creeping alongwith shaft into motor housing is prevented. It shall
also prevent dirt and water from getting into the motor.
d) Unless otherwise approved, bearing lubrication system shall be
such that no internal forced oil or water is necessary to maintain the
required oil supply or to keep bearing temperature within
permissible limits.
e) For oil lubricated bearings, drain plugs shall be provided by draining
and residual oil when required.
16.11 ENCLOSURES:
a) Motors to be installed outdoor shall have hose proof enclosure
equivalent to IP-55 as per IS:4691. For motors to be installed
indoor, the enclosure, shall be dust proof equivalent to IP-54 as per
IS:4691.
b) Two independent earthing points shall be provided on opposite side
of the motor for bolted connection of earthing conductor.
Volume-II
45
400KV 500 MVA Transformer
c) Motors shall have drain plugs so located that they will drain water,
resulting from condensation or other causes from all pockets in the
motor casing.
d) Motors weighing more than 25 Kg shall be provided eyebolts, lugs
or other means to facilitate lifting.
16.12 COOLING METHOD : Motors shall be of self ventilated type having TEFC
(total enclosed fan cooled) enclosure.
16.13 RATING PLATE : The rating plate shall confirm to the requirements of IEC
incorporating the year of manufacture.
16.14 OPERATIONAL FEATURES:
a) Continuous motor rating (name plate rating) shall be at least ten
(10) percent above the maximum load demand of the driven
equipment at design duty point and the motor shall not be
overloaded at any operating point of driven equipment that will arise
in service.
b) Motors shall be capable of giving rated output without reduction in
expected life span when operated continuously.
16.15 STARTING REQUIREMENT: All induction motors shall be suitable for full
voltage direct-on-line starting. These shall be capable of staring and accelerating to
the rated speed alongwith the driven equipment without exceeding the acceptable
winding temperature even when the supply voltage drops down to 85% of the rated
voltage
17.0
PAINTING:
17.1
It has been observed that certain units received in the past by us are
not having good quality painting on inside & outside and with passage of time
peeling of flakes of paint takes place. In view of this the Tenderers are
requested to furnish in a separate sheet, painting procedure adopted by them
for internal & external surfaces of the tank. This is an essential requirement
and details should be confirmed by the Tenderer in their offer. The internal
and external surfaces including oil filled chambers and structural steel work to be
painted shall be shot or sand blasted to remove all rust and scale of foreign
adhering matter or grease. All steel surfaces in contact with insulating oil shall be
painted with two coats of heat resistant, oil insulating varnish.
17.2
All steel surfaces exposed to weather shall be outside paint – one coat of
chemical + thermal resistant epoxy primar and two coats of chemical + thermal
resistant epoxy light grey paint with thickness 150 microns (Min) with shade no.631
of IS-5. The inside paint- oil+ heat resistant full glossy white paint with thickness 40
microns (Min). For each transformer, oil paints should be obtained from same source
to ensure compatibility & proper finish. The AKSONOBEL paint should be used in
both inside & outside painting.
Volume-II
46
400KV 500 MVA Transformer
17.3 All paints shall be carefully selected to withstand extremes of weather. The
paint shall not scale off or crinkle or be removed by abrasion due to normal
handling. The process of painting should be clearly described. The supplier shall
also includes supply of paint of 10 liters for touching purpose during erection/
commissioning of transformer.
17.4 Bolts & Nuts :All bolts and nuts exposed to weather shall be hot dipped
galvanised/cadmium plated.
18.0
WIRING & CABLING :
(a) All external cabling will be carried out by the purchaser based on
wiring diagram & interconnection schedule to be supplied by the
Tenderer. Cable box/sealing end shall be suitable for following
types of cables :i) POWER SUPPLY 0.415KV : 1100 volts grade PVC insulated
armoured aluminum cable .
ii) CONTROL CABLE
: 1100 volts grade PVC insulated
7/0.737mm stranded armoured
copper cable .
Size of the Purchaser’s cable will be intimated to
the
successful TENDERER after detailed engineering.
(b) Compression type cable gland shall be provided for termination
of power and control cables.
(c) All controls, alarms, indicating and relaying devices provided
with the transformer shall be wired upto the terminal blocks
inside the Cooler Control Cabinet.
(d) All devices and terminal blocks with the Cooler Control Cabinet
shall be clearly identified by symbols corresponding to those used
on applicable schematic or wiring diagrams.
(e) Not more than 2 wires shall be connected to one terminal. Each
terminal shall be suitable for connecting two 7/0.737mm stranded
copper conductors from each side.
(f) All internal wiring shall be securely supported, neatly arranged,
readily accessible and connected to equipment terminals and
terminal blocks.
(g) Engraved code identification plastic ferrules marked to
correspond with schematic diagrams shall be fitted at both ends of
wires. Ferrules shall fit tightly on wires and shall not fall off when
the wire is disconnected from terminal block.
(h) The schematic diagrams of circuitry shall be available in the
respective cabinets (local OLTC control cabinet , local fan control
cubicle and RTCC panel). The diagrams shall be mounted on the
inner side of door of cubicle/cabinets. The arrangements shall be
such that it is not be possible to remove the diagram from its place
and diagrams are long lasting (engraved type).
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47
400KV 500 MVA Transformer
19.0
TERMINAL CONNECTORS:
19.1 Terminal connectors for HV / IV /LV side bushings shall be suitable for
double (twin)/ double (twin)/ (single) Moose ACSR (31.77 mm) conductor
respectively with sub conductor spacing of 450/300 mm for HV/IV and suitable
for horizontal and/or vertical takeoff arrangement i.e. universal type. All terminal
clamping arrangement shall be subject to Purchaser’s approval. Regarding neutral
earthing, details have been indicated in clause no. 12.1 of this specification and
arrangement shall be as per drawing no. MPPTCL/500MVA/01. Two (2) no. terminal
connectors for Earth pit end connection suitable for double (twin) Moose ACSR
(31.77 mm) conductor shall also be supplied loose as per drawing no.
MPPTCL/500MVA/03 .
19.2
Bushing terminals shall be provided with terminal connectors of approved
type and size for connection to external parts. Terminal connectors offered must
have been successfully type tested as per IS-5561.
19.3
All terminal connectors shall be manufactured out of gravity dye casting
process only and shall be free from blow holes, surface blisters, cracks and
cavities. All sharp edges and corners shall be blurred and rounded off. The
aluminum alloy castings, if used, shall conform to relevant IS.
19.4
No part of the clamp shall be less than 12mm thickness.
19.5
All bolts, nuts and washers shall be of Hot Dip Galvanised.
19.6
For bimetallic clamps, bimetallic strip of not less than 2 mm thickness
shall be provided.
19.7
Flexible connectors, if provided shall be made from tinned copper sheets.
19.8
Size of terminal (bushing stud)/conductor ( ACSR Moose ) for which the
clamp is designed and also rated current under site conditions shall be embossed/
punched on each part of the clamp, except hardware.
19.9
All current carrying parts shall be designed and
minimum contact resistance.
19.10
manufactured to have
Clamps shall be designed corona controlled.
19.11 The nominal current rating and short time current rating of terminal
connectors shall match the corresponding rating of respective bushings i.e., 63KA
for 3 seconds for 400kV, 40KA for 3 seconds for 220kV & 31.5KA for 3 seconds for
33kV.
20.0
INSULATING OIL REQUIRED FOR TRANSFORMERS:
20.1
Transformer oil shall be supplied by the Bidder. The offered Price of
transformers therefore, should include first filling of oil( including wastage) & 10%
extra of that quantity. The quantity of oil for first filling including wastage and 10%
extra of that quantity should be indicated by the Bidder in kilo-liters and in kg in the
technical questionnaire. The design of the transformer shall be based on the
Volume-II
48
400KV 500 MVA Transformer
characteristic of EHV transformer oil as per relevant IS. Transformer oil for each
transformer covered under this Bid specification shall be supplied separately.
20.2 Although oil for the transformer is included in the scope of supply, but it may
be noted that the transformer shall be supplied duly N2 gas filled with suitable
arrangement to ensure that the pressure of gas is regularly maintained during
transit and upto the date of filling of oil. For this purpose, necessary gas
cylinders with regulator shall be supplied on non-returnable basis. Additional gas
cylinders required recouping and maintaining of positive Nitrogen pressure
upto filling of oil should be supplied by the manufacturer of Transformers and
the offered price should take into account this requirement.
20.3 The quality of the oil supplied with transformer shall conform to the oil
parameters specified in this clause. No inhibitors shall be used in the oil. The oil
samples of transformer will be drawn for the oil used at factory & site as follows.
i.
Prior to filling
ii.
Before and after heat run test / pre-commissioning test
iii. Before energizing.
All tests as per IS:335 (latest revision) shall be conducted on oil samples.
20.4
Sufficient quantity of oil necessary for first filling of main tank, coolers,
radiators and conservators etc. upto the proper level plus anticipated quantity of
wastage of oil during first filling shall be supplied in tankers. Please note, wastage
means quantity of oil absorbed during initial filling at works for testing. In addition to
the oil needed for first filling, 10% extra quantity of oil for topping up in future, shall
be supplied in non-returnable containers suitable for outdoor storage. Therefore, total
quantity of oil required for first filling shall be measured at works at the time of testing
on unit subjected to heat run test.
20.5
The supplier shall dispatch the transformer in an atmosphere of pressurised
Nitrogen. In this case, necessary arrangement shall be ensured by the supplier to
take care of pressure drop of nitrogen during transit and storage till completion of oil
filling during erection. A gas pressure testing valve with necessary pressure gauge
and adapter valve shall be provided.
20.6
The supplier shall warrant and confirm that oil to be used for the transformer
testing at Works & oil to be supplied for the transformer is free from Polychlorinated
Biphenyls (PVB/PCB). The transformer oil to be used and supplied by the bidder for
first filling at site shall be new oil of EHV Grade-I having technical specification
mentioned hereunder. Oil to be used by the manufacturers at factory for the purpose
of testing at their works shall be of good quality having parameters matching with the
parameters specified in the specification. Specific approval of oil test results of oil
proposed to be used for testing of transformer in factory shall be obtained by the
manufacturer from the purchaser before filling in the unit.
S
No.
1.
Volume-II
Characteristics
Technical Requirement
Test Method
Appearance
Oil shall be clear, transparent
and free from suspended matter
A representative sample
of the oil shall be
49
400KV 500 MVA Transformer
or sediments
2.
Density at 29.5°C (Max)
0.820-0.895 g/cm3 (max)
3.
Kinematic viscosity (mm2/s)
4.
5.
Interfacial tension at 27°C
Flash point
3 (max) at 100°C
12 (max) at 40°C
1800 (max) at - 30°C
0.04 N/m (min)
140°C (min)
6.
Pour point
-30°C (max)
7.
0.01 mg KOH/g (max)
8.
Neutralization value (total
acidity)
Corrosive sulphur
9.
Total Sulphur Content
0.15% (max)
10.
11.
Negative Impulse Strength
Electric Strength
(Breakdown voltage)
a. New unfiltered oil (as
received condition)
b. After filtration
150 kV(min)
12.
13.
14.
15.
16.
17.
Dielectric dissipation factor
(tan delta) at 90 °C
Water Content
Specific resistance
a. at 90°C
b. at 27°C
Oxidation stability
a. Total acidity
b. Sludge
c. DDF- @90 °C
Ageing characteristics after
accelerated ageing test
a. Resistivity at 27°C
b. Resistivity at 90°C
c. Dielectric loss factor
(tan delta) at 90°C
d. Total acidity
e. Sludge content after
ageing
Presence of oxidation
inhibitor
Volume-II
examined in a 100 mm
thick layer at ambient
temperature
ISO 3675 or ISO 12185
or ASTM D 4052 IS 1448
(Part 16)
ISO 3104 or ASTM D445
or ASTM D7042 IS 1448
(part 25)
ISO 6295 or ASTM D971
ISO2719 IS 1448
(Part 21)
ISO 3016 or ASTM D97 IS
1448 (part10 Sec 2)
IEC 62021-1
Or ASTM D974
IEC62535 DIN 51353 or
ASTMD1275B
BS 2000 part 373 or ISO
14596
ASTMD-3300
IEC 60156 / IS 6792
Not corrosive
40 kV (rms) (min)
70 kV (rms) (min)
Less than 0.002
Max 20 ppm (as received) /less
than 10ppm (after filtration) for
filling in the tank
100x1012 ohm cm (min)
1500x1012 ohm cm (min)
After 164 Hrs @ 120 °C
1.2 mg (max)
0.8% (max)
0.500 (max)
IEC 60247 or IEC 61620
Or ASTM D 924 IS 16086
IEC 60814
IS:6103
IEC 61125 (method C) or
IS 12422 (method C)
IS 12177
2.5x1012 ohm cm (min)
0.20x1012 ohm cm (min)
0.15 (max)
0.05 mg KOH/gm
0.05% (max) by weight
Not detectable (<0.01%)
50
IEC 60666 or ASTM
D2668 or D4768
IS 13631
400KV 500 MVA Transformer
18.
Carbon Type Composition
Aromatic
Naphthenic
Paraffinic
Dibenzyl Disulphide
(DBDS)
2-Furfural and related
compounds content
Not detectable (<0.05mg/kg) for
each individual compound
21
PCA content
3% (max)
22
PCB content
Not detectable (<2 mg/kg)
19.
20.
IEC 60590 and IS 13155
or ASTM D 2140
4- 12%
> 42%
< 50%
Not detectable (<5 mg/kg)
IS 16497 (Part 1)
IEC 61198
Or ASTD M 5837
IS 15668
BS2000 Part346
IEC 61619
or
ASTM D 4059 IS 16082
Note:Particles in the oil (For 400 kV and above transformer & reactor) : The particle
analysis shall be carried out in an oil sample taken before carrying out FAT at
manufacturer’s works and after completion of the oil filtration at site. The procedure
and interpretation shall be in accordance with the recommendation of CIGRE
report WG-12.17- “Effect of particles on transformer dielectric strength”. Particle
limit as shown below shall be ensured by manufacturer, implying low contamination,
as per CIGRE Brochure 157, Table 8. After filtration the oil is to be flushed and
particle count to be measured. Limiting value for the particle count are 1000
particle/100 ml with size ≥ 5 μm; 130 particle/100 ml with size ≥ 15 μm.
20.7 AIR CELL: Our technical specification calls for supply of power transformers
with air cell type oil preservation system. It is obligatory on the part of the
Tenderers to clearly submit complete constructional and technical details of sealing
arrangement, duly supported with technical details, pamphlets and dimensional
drawings. While furnishing details for the above sealing arrangement the
Tenderers must confirm clearly that the size and capacity of sealing arrangement
is adequate for the transformer and for the quantity of oil required for the
transformers. Necessary calculation/documentary proof shall be furnished.
20.8 Air cell type oil preservation system included with each transformer shall
ensure as under:
(a) The air inlet of COPS (Conservator Oil preservation System) shall be
properly fitted on the conservator for leak proof arrangement to ensure
that the air does not come in contact with oil under any circumstances.
(b) The size and capacity of the COPS (Conservator Oil preservation
System) shall be selected to suit the design of Conservator and to ensure
proper operation for the quantity of oil in the unit with the proper
allowances. The COPS shall be of reputed make, proven design and of
established performance. Details in this regard are to be submitted with
the offer by the Tenderer for verification . The Tenderer is required to
submit calculation with Tender to prove adequacy of air cell & its size.
Volume-II
51
400KV 500 MVA Transformer
(c)
The Tenderer shall clearly indicate in the manual the procedure for
installation of COPS and precautions to be taken at the time of first oil
filling under vacuum in the transformer.
20. 9 SPECIFICATION OF FIRE PROTECTION SYSTEM : Nitrogen Injection Fire
Protection System/ Nitrogen injection type fire prevention & extinguishing system
with flow sensitive conservator isolation valve alongwith MS oil storage tank shall be
provided for all the transformers.
20.9.1 Nitrogen Injection Fire Protection System (NIFPS) shall be designed to
prevent explosion of transformer tank and the fire during internal faults resulting from
arc and also to extinguish the external oil fires on transformer due to tank explosion
and/or external failures like bushing fires, OLTC fires and fire from surrounding
equipments, etc. The system shall work on the principle of Drain & stir. On
activation, it shall drain a pre-determined quantity of oil from the tank top through
drain valve to reduce the tank pressure, isolate conservator tank oil and inject
nitrogen gas at high pressure from the bottom side of the tank through inlet valves to
create stirring action and reduce the temperature of oil below flash point to
extinguish the fire. The quantity of oil removed from the tank shall be such that
adequate amount of oil shall remain to cover active part, i.e. core coil assembly even
after stoppage of oil drain. Electrical isolation of transformer shall be an essential
pre-condition for activating the system. The NIFPS shall conform to NEPA 70
standard titled “ Fire protection of transformers & transformer vaults” and
Tariff Advisory Committee (TAC) regulations.
20.9.2 OPERATIONAL CONTROLS: The system operation shall be fully automatic
and activate from the required fire and other trip signals. In addition to automatic
operation, remote operation from control room/ remote centre and local manual
control in the fire extinguishing cubicle shall also be provided. System shall operate
on following situations.
20.9.3 PREVENTION OF TRANSFORMER EXPLOSION AND FIRE: To prevent
transformer explosion and fire in case of an internal fault, signals given by operation
of Electrical protection relays and tripping of circuit breaker of transformer and
operation of either Buchholz relay, or pressure relief valve (PRV) alongwith Rapid
Pressure Rise Relay (RPRR) shall be used to activate the system and logic for
RPRR for system activation should include for operation of Electrical
protection relays and tripping of circuit breaker of transformer. The exact logic
for system activation shall be finalized during detailed engineering.
20.9.4 FIRE PROTECTION: In case of fire, sensed by fire detectors, the system
shall be activated only after electrical isolation of the transformer, confirmed by
breaker trip. If the fire detection is not associated with any other fault, the system
activation shall be only manual. Manual operation switch shall be provided in the
control room/ remote control centre with a cover to avoid accidental operation of it.
20.9.5 OPERATION OF SYSTEM: On receiving activation signal, the following shall
take place:
i. Open the quick opening drain valve to drain the top layer oil
Volume-II
52
400KV 500 MVA Transformer
ii.
Shut off the conservator isolation valve to prevent flow of oil from the
Conservator tank to the main tank.
iii. Open the Nitrogen regulator valve to inject Nitrogen into the transformer
tank to create stirring of oil.
There shall be interlock to prevent activation of the system if the transformer is not
electrically isolated. There shall also be provision for isolating the system during
maintenance and/or testing of the transformer.
20.9.6 TECHNICAL PARTICULARS: The supplier shall be responsible for the
design of the complete system and shall submit the drawings and design
calculations for the number of fire detectors, pipe sizing of drain pipe and Nitrogen
injection pipe, Nitrogen cylinder capacity, number of injection points, etc. and get
approval from purchaser. Facility shall be provided to test the system when the
transformer is in service, without actually draining the oil and injecting Nitrogen. The
Nitrogen regulator valve shall be designed in such a way that the Nitrogen shall not
enter the transformer tank even in case of passing/ leakage of valve. The system
shall work on station DC supply. MPPTCL shall give two distinct DC feeders in
control. The control box of fire protection system shall have facility to receive these
feeders for auto changeover of supply. It shall be the contractor’s responsibility to
further distribute power to the required locations.
Following indications and alarms shall be provided in the cubicle as well as
the control box:• Nitrogen cylinder pressure indication.
• Nitrogen cylinder pressure low.
• Fire in Transformer/ Reactor.
• Oil drain started.
• Conservator oil isolation valve, oil drain valve & gas inlet valve closed.
• Nitrogen injection started
• DC supply fail
• Pressure indicators for Nitrogen pressure in the cylinder after nitrogen regulator
and Oil leak detector chamber is to be incorporate in FEC to provide indication in
control box.
20.9.7 DETAILS OF SUPPLY & WORK FOR SYSTEM EQUIPMENTS AND
OTHER RELATED ACTIVITIES: The scope of supply shall include the following
items, any other items required for safe & trouble free operation of the system and
the scope of works include complete earthwork (i.e. excavation, backfilling etc.),
scope of supply also includes services to be availed by the purchaser for erection
and commissioning of NIFPS at EHV sub-stations of MPPTCL in MP., civil work with
civil material for the entire open/ buried piping and requisite foundations for the fire
protection system, construction of safety wall, construction of oil pits with provision of
oil storage tank of MS and pipe supports for open/ buried, entrenched and
overground piping. Further, civil works shall be in scope of NIFPS manufacturer to
avoid any complication in future. The system design shall also conform to
TAC/NFPA norms.
(i) Fire extinguishing cubicle with base frame and containing at least the following:
Volume-II
53
400KV 500 MVA Transformer
• Nitrogen gas cylinder of sufficient capacity with pressure regulator and
manometer with sufficient number of adjustable NO contacts.
• Oil Drain Assembly including oil drain pipe extension of suitable size for
connecting pipes to oil pit.
• Mechanical release device for oil drain and nitrogen release.
• Limit switches for monitoring of the systems.
• Panel lighting.
• Flanges on top of the panel for connecting oil drain and nitrogen injection pipes
for transformer.
• Limit switch for pressure switch/sensor.
• Pressure indicators for Nitrogen pressure in the cylinder and after Nitrogen
regulator.
(ii) Control box to be installed in the control room of the station for monitoring system
operation, automatic control and remote operation, with alarms, indication light,
switches, push buttons, audio signal, suitable for tripping and signaling.
(iii) Conservator isolation valve which shall be flow sensitive and shut off when the
flow in the pipe is more than the flow expected in the permissible normal
operating conditions. It shall be provided with position indicator remote alarm
indication.
(iv) Required number of fire detectors to be located in strategic locations to be
finalized during detailed engineering. One set (30%) of fire detectors for NIFPS
shall be supplied as spare for future replacement.
(v) Flow Sensitive Conservator Isolation Valve.
(vi) All controls, alarms, panels, cables, cable trays (if required), junction boxes,
valves etc.
(vii) Provision of monitor the Nitrogen display and also indication for leakage from
drain pipe is to be incorporated in control box and its respective schematic
drawings. Further leak detector chamber is to be incorporated in FEC to avoid oil
leakage problem. Specify quantity of detectors of NIPFS and its location on
transformer top cover. Also furnish supporting calculations for selection of
number of fire detectors and time of extinction period.
(viii)MS Oil Storage Tank : Each transformer unit shall be provided with an
underground MS oil storage tank. The MS oil storage tank shall have non
corrosive, water proof, epoxy coated (from inside) mild steel (minimum thickness
5 mm) to store drained out oil on operation of NIFPS. The total capacity of
storage tank shall be at least 10% of transformer tank oil to avoid overflowing of
oil considering that drained oil volume shall be around 10% of transformer tank
oil. Necessary arrangement shall be made on underground storage tank so as to
take out the drained oil from the tank for further processing and use. All the pipe
and physical connection from transformer to oil pit shall be in the scope of
bidder. The design of tank and pit shall be finalized during approval of drawing.
(ix) In this connection, to review such working of NIFPS a committee has been
formed, the committee has suggested following points for improvement in NIFPS
as detailed under:a. To ascertain how much percentage of oil drained and time required for
draining, oil flow sensor shall be arranged.
b. For event logging of complete process through PLC based systems
provisions should be made. Demo for oil draining shall be arranged.
Volume-II
54
400KV 500 MVA Transformer
c. For overhauling of system, company service engineer should visit the site
yearly for maintenance purpose.
20.9.8 INSTALLATION AND PRE-COMMISSIONING TEST: After installation the
system pre-commissioning tests shall be carried out jointly with the MPPTCL
representative before the system is put in service.
20.9.9 In order to restrict the supply of oil in case of a fire in transformer, provision
shall be made to isolate the conservator oil from the main tank.
20.9.10 A valve which shall be flow sensitive and shut off when the flow in the pipe
is more than the flow expected in the permissible normal operating conditions. This
valve shall be located in the piping between the conservator and the buchholz relay
and shall not affect the flow of oil from and to the conservator in normal conditions.
20.9.11 When the flow from conservator to main tank is more than the normal
operating conditions, the valve shall shut off by itself and will have to be reset
manually. It shall be provided with valve open/close position indicator along with
alarm indication in control room during closing operation of valve.
20.9.12 Necessary switches shall be provided in cooler control cabinet / common
marshalling box for manual open / close operation of the valve.
Tenderers shall offer Transformers completely fitted with Nitrogen Injection
Fire Protection Systems, separately in their offer in schedule of prices.
20.10 ON LINE MONITORING DEVICE FOR TRANSFORMER:
20.10.1 The TENDERER should offer for a suitable on line monitoring device for
regular monitoring of 3 key gases and moisture for condition assessment and fault
detection of the 400 KV 500 MVA transformer. The device should measure
3 key dissolved gases viz. Hydrogen, Acetylene, Carbon mono oxide with accuracy
of ±10%. The minimum range of measurement of dissolved gases shall be
Hydrogen :5 to 500, Acetylene : 3 to 5000, Carbon mono oxide : 10 to 5000.
The moisture content shall be measured from 0 to 100 % RS (in ppm). The device
shall have non volatile memory storage to prevent loss of data. The device shall be
provided with user configurable at least six alarm contacts & two front panel LED
arrays. The alarm setting screen shall be available for setting alarms based on level
of 3 Key gases or moisture and rates of change for Key gases. For configuring the
six alarm settings, suitable PC software shall be provided alongwith PC/Desktop and
suitable connection cables upto control room shall be done by supplier with the
device. The device shall be supplied with two separate channels for remote
communication plus local USB and Ethernet connections. The device should support
communication Protocol viz. MODBUS, DNP 3.0 and IEC-61850. It shall be possible
to configure sampling rates to hourly/ daily. The alarm & Caution thresholds shall be
user configurable. The device should support Load monitoring by analyzing results
with loading of Transformer and device shall be provided with suitable software for
graphical trending & diagnostic analysis of results. The device shall have minimum
maintenance requirements.
Volume-II
55
400KV 500 MVA Transformer
On line monitoring unit shall not be mounted on the body of the transformer.
A separate mounting arrangement near the transformer body with proper protective
sheds & covers for protection against sun and rains be provided. The mounting
cubical shall have provision for ventilation/cooling and also provision for reading of
parameters by operators without opening the box. The associated mounting
structure, foundation bolt and civil works are in scope of supplier. On line monitoring
unit shall be complete with provision for remote monitoring alarm and indication in
RTCC panel in control room. Complete details of offered device shall be submitted
by the Tenderer and explained by suitable manual/pamphlets.
External temperature range : 0 to 55 o C
Operating Humidity
: 10 to 95% RH non condensing
Enclosure
: IP:55
Input Power requirement
:
Voltage 120 to 260 V AC, Frequency 47 to 60 Hz;
The power supply should be able to withstand
electrical surges & disturbances prevalent in EHV
substation.
20.10.2 Tenderers shall offer Transformers completely fitted with On Line
Monitoring Device for Transformer of Kelman or equivalent make, suitable for
monitoring of 3 Key gases, separately in their offer in schedule of prices.
20.11 THERMOSYPHON FILTER
Atleast four Nos. of Thermosyphon filter arrangement each of capacity 1/5th
of the total oil flow in the cooler shall be provided with rigid support (i.e., slotted one
not acceptable) on the transformer along with connecting piping, isolating valves at
either end, drain plug shall be mounted on the transformer. It will have Alumina trap
and will be designed in such a way that 1/5th of the forced oil circulation passes
through it. The quantity of absorbent will be 0.25% of the total weight of total oil in
the transformer, cooler, conservator etc. Spare alumina for one time replacement
shall be also supplied by the supplier. The location of Thermosyphon filter should be
in such a way that same do not interfere with any of the existing equipments. The
Thermosyphon filter shall be located at diagonally opposite points of transformer and
out of four filters, two filters shall be with pumps .The connecting pipes of
Thermosyphon filter to tank shall be provided with flexible couplings. It may be noted
that rigid supports shall be provided for thermosyphon filter i.e., slotted type of fixing
arrangement is not acceptable.
20.11.1 SELF REGENERATING MAINTENANCE FREE DEHYDRATING
BREATHERS FOR TRANSFORMERS: Minimum 2 nos. self-regenerating
maintenance free dehydrating Silica Gel Breathers each of 100% breathing capacity
are required separately for Main & OLTC Conservator. Suitable arrangement for
parallel mounting of breathers shall be made for connecting the Silica Gel Breathers
to the main conservator. Size of breather and its pipe connection is to be indicated.
The passage of air should be through dual filter & Silica Gel. Silica Gel shall be
Volume-II
56
400KV 500 MVA Transformer
isolated from atmosphere. Adequate supports are required to be provided for pipe
connection to avoid any swing in air
The capacity of breather shall be adequate to ensure supply of dry air only
for the volumetric expansion/contraction of oil keeping in view the total quantity of
oil in the unit. The container of the breather shall be made of metal with glass
enclosure along its periphery to ensure that the transparency (to verify the color of
dehydrating agent) is maintained during operation directly under sunlight (ultra
violet rays) for long life.
General requirement of the self-regenerating
maintenance free dehydrating Silica Gel Breathers shall be as under;
1. The transformer main tank conservator and OLTC conservator shall be
fitted with a completely separate and independent silica gel breathers of the
Maintenance-Free type in a convenient floor height at eye level. Both
breather should have modular humidity sensors to regulate regeneration
operation. Each breather of adequate capacity having its pipe connection of
minimum size of one inch dia shall be preferable.
2. A stainless-steel filter at the bottom shall protect the silica gel chamber
against external environment influences.
3. This condition-controlled regeneration (with help of humidity & temperature
sensor) application shall be environment friendly.
4. Material of External Construction of the Breather: All external parts must be
suitable for mounting for outdoor use, resistant against transformer oil and
ultraviolet rays. Material used in the construction of the breather to ensure
durability.
5. Important function of breather is to dehumidify air entering in transformer
during inhale. It should not affect breathing process of transformer. Hence
there should be no moving parts in construction of breather which could
restrict or redirect air flow from the desiccant chamber, to ensure
uninterrupted breathing of transformer. Moving parts can cause serious
troubles by blocking breathing of transformer.
The requirement briefed above are the general requirement, however the
detailed requirement/ make etc, shall be finalized at the time of drawing approval
with successful bidder.
20.12 SURGE CAPACITORS: The Tenderer has to provide with each 400KV
500MVA transformer, three (3) nos 40 KVrms, 0.125 micro farad Surge Capacitors
with mounting structure & terminal connectors for connection to 72.5 KV tertiary
bushings. The complete technical particulars of capacitor units has been specified in
Annexure I. The constructional features of the surge capacitors shall be as under :
a)
The dielectric fluid within the capacitor unit shall be environmentally safe and
biodegradable. PCB type fluid shall not be used. The capacitor elements shall
be vacuum dried inside the case prior to impregnation with dielectric fluid. After
impregnation, the capacitor unit shall be sealed immediately upon removal of
impregnating reservoir.
Volume-II
57
400KV 500 MVA Transformer
b)
The capacitor shall include bushings, discharge resistor, capacitor elements
connected in series and/or parallel, internal connections etc. All joint of casing
shall be tested for leaks.
c)
Each capacitor unit shall be provided with lifting eyes or similar provision for
lifting or placing the unit into its position.
d)
Each capacitor unit shall be provided with discharge device which reduces the
residual voltage from the crest value of rated voltage to less than 50 Volt within
one minutes after the capacitor is disconnected from the source of supply.
e)
Surge capacitor shall be mounted on a support structure. Associated support
structure & foundation bolt shall be supplied by the Supplier.
f)
The surge capacitor shall have adequate strength to withstand without damage
or loss of life the mechanical load both in operation and transportation,
handling and erection. The loads shall include electromagnetic forces including
those during fault external or internal to the capacitors, wind loading forces due
to expansion and contraction due to ambient temperature, load variation and
seismic efforts.
g)
The capacitor units shall be interchangeable in order to reduce spare
requirements and simplify maintenance procedures.
h)
The bushings of the capacitor shall be of porcelain or oil communicating type.
The bushings and other insulators shall have creep age of 25 mm per KV of
phase to earth voltage. Bushing terminals shall be provided with terminal
connectors for interconnection with adjacent equipment or bus bars.
21.0
FITTINGS & ACCESSORIES FOR THE POWER TRANSFORMERS:
21.1 Only those offers will be considered for evaluation wherein the Tenderers
submit a specific confirmation that the transformers will be supplied complete with
all fittings and accessories exactly in line with various requirements indicated in
Annexure II in this technical specification. The basic offered cost must take into
consideration cost of all fittings and accessories
as under and indicated
elsewhere in this specification otherwise the Tender will be treated as non
responsive.
21.2 The equipments and accessories furnished with the transformer shall be
suitably mounted on the transformer for ease of operation, inspection and
maintenance and the mounting details shall be subject to the approval of the
purchaser. All valves shall be provided either with blind companion flanges or
with pipe plugs for protection.
21.3 Indication, alarm and relay equipment shall have contacts suitable for
operation with 220V DC supply. Any other accessories or appliances
recommended by the
manufacturer
for
the satisfactory operation of the
transformer shall also have 220V DC as input.
a) OLTC and its controls shall be as per clause 14.
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400KV 500 MVA Transformer
b) All cabinets & panels shall be conforming to stipulations under
Clause-16 .
c) All 420KV, 245KV, 72.5KV phase bushings and 72.5 KV neutral bushings
shall be of RIP condenser type and as per Clause 11.13 .
21.4. Equalizing pipes for maintaining equal pressure between main tank and
OLTC and at various other locations as per design shall be provided. These
equalizing pipes shall be routed such as not to create any obstruction.
21.5 Accessories, which are not included in the above schedule but details
of which are given in Tender specification and which are necessary for satisfactory
operation of Transformer shall be deemed to have been included in the accepted
price without any extra cost to the Purchaser.
21.6 It may be noted that all the name plates/rating plates/diagram plates on
transformer shall be engraved type/anodized type and shall be fixed using
rivets/spot welding method. The method of printing of letters on the R&D plate shall
be such that inscriptions shall not fade by ultra violet rays and other adverse
weather conditions under which the same is subject to during service life of
transformers.
(a)
Rating & Diagram Plate: In the R&D plate following additional information
over & above as specified in the IS/CBIP specification shall be provided.
-
Weight of the copper for windings (bare & with paper insulation)
Weight of the core laminations .
Weight of insulation
Transport weight
Weight of steel
Untanking weight (Core & Coil)
Weight of Transformer Tank along with Fittings & Accessories
Percentage Impedance at all taps
HV & IV windings resistance of all phases at all taps
LV winding resistance of all phases
Weight of the oil for first filling (including wastage) in Kg/Liters
Total quantity of oil including 10% extra quantity in Kg/Liters
If required two separate R& D plates may be used.
(b)
Valve Schedule Plate: In the valve schedule plate, at least two views
should be inscribed so that location of all the valves provided on the
transformer could be indicated/visualised. In the table of valve schedule
plate, details of valves viz. type, material, size & position during
transportation and after commissioning shall be clearly indicated. The size of
the letters shall be such that the same be visible clearly to a person standing
away at a distance of one meter from the respective vertical face of the
transformer.
(c)
Instruction Plate For Oil Filling in the Conservator with Air Cell: An
instruction plate shall be provided for oil filling in the conservator having air
Volume-II
59
400KV 500 MVA Transformer
cell type breathing arrangement. In addition to the instructions for oil filling on
this plate, a diagram indicating mounting details of MOLG, oil level gauges,
air cell inside the conservator with a pictorial view of conservator including
make, type & size of air cell shall also be inscribed. The location of plate
should be such that same is visible to operating personal from a distance as
mentioned in (b) above.
22.0 CENTRE OF GRAVITY : The centre of gravity of the assembled transformer
shall be low and as near to the vertical centre line as possible. The transformer
shall be stable with or without oil. If the centre of gravity is eccentric relative to track
gauge either with or without oil, its location shall be shown on the outline drawing.
23.0
PACKING :
23.1 The packing may be in accordance with the Tenderer’s standard practice
but Tenderer should give full particulars of packing for the approval of the
purchaser. Special arrangements should be made to facilitate handling and to
protect the projecting connections for damage in transit.
23.2 The transformer shall be transported filled with inert gas preferably Nitrogen
gas. The Tenderer shall ensure that adequate pressure of gas is maintained
inside the tank throughout during transportation by sending escorts and required
apparatus and equipment with the transformers.
23.3 All parts shall be adequately marked to facilitate field erection. Boxes and
crates shall be marked with the contract number and shall have a packing list
enclosed showing the
parts contained therein. however the verification of
accessories shall be done in presence of suppliers representative.
24.0
TESTS:
24.1 The manufacturer shall carryout routine test ,additional routine tests and
type tests on the transformers as per the relevant Indian Standard IS-2026 with
latest amendments , IEC 60076, CBIP Publication No 295, IEEE or any equivalent
International Standard .The details of tests are specified hereunder. It should be
specifically noted by the Tenderer that testing of each & every transformer included
in this bid specification shall be carried out at the manufacturer’s works in fully
assembled condition complete with all fittings & accessories.
It is to note that on receipt of call from your end for final inspection of each
unit , testing of the unit shall be carried out in presence of our inspecting officer in
line with approved QAP. However, after final testing , one of the unit as decided by
MPPTCL may be sent for testing at accredited laboratory (i.e. CPRI) at our cost for
conducting routine/type tests as decided by us and to ensure correctness of
measured no load losses & load including stray loss + Auxiliary losses and
temperature rise of oil and winding.
24.2 ROUTINE TESTS AND ADDITIONAL ROUTINE TESTS: All routine tests
and additional routine Tests detailed under clauses 24.2.1 & 24.2.2 herein under
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400KV 500 MVA Transformer
will be carried out on each transformer on "free of cost" basis, in accordance with
IS:2026 part-I.
24.2.1 ROUTINE TESTS
a)
Measurement of winding resistance as per cl.16.2 of IS 2026 Part
I. The winding resistance shall be measured on all taps and of all the
three phases and values be recorded in respective test certificates.
b)
Measurement of voltage ratio & % error at all taps and checking of
voltage vector relationship as per cl.16.3 of IS 2026 Part I.
Measurement of Impedance voltage/ short circuit impedance &
load loss (at principal tap & extreme taps) as per cl.16.4 of IS 2026
Part I, IEC 60076. Also measurement of Impedance voltage/ short
circuit impedance at all taps at low voltage supply.
c)
d)
Measurement of no load loss at 90%, 100%, 110% of rated voltage
& no load current as per cl.16.5 of IS 2026 Part I.
e)
Measurement of insulation resistance as per cl. 16.6 of IS 2026
Part I.
f)
Dielectric tests shall be carried out as per IS 2026 (part I, II & III) &
IEC60076 as under
i.
400 KV winding
- Lightning impulse on all the line terminals (routine test)
- Induced over-voltage with partial discharge indication On all the
line terminals (routine test)
- Separate source AC on neutral terminal (routine test)
- Switching Impulse test
The test voltage between line and neutral shall be brought upto
420 KV and held for 5 seconds. It shall then be reduced to 364
KV. This shall be held for 30 minutes where after the voltage
shall be reduced to zero. During the 30 minutes period at 364 KV
between the line and neutral, observation of partial discharge
shall be carried out at line as well as neutral terminals of the
winding under test. Further, following conditions shall be
specifically verified
Note : There shall be no breakdown during short application of
higher voltage i.e 420 KV and the continuous level of partial
discharge during the long application of lower test voltage shall
not exceed 500 pico-Coulomb in any of the measuring channels.
ii. The 220 KV winding
- Lightning impulse on all the line terminals (routine test)
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400KV 500 MVA Transformer
- Induced over voltage test with partial discharge indication
(routine) .This test gets simultaneously done when 400 KV
winding is tested, therefore, no separate test needs be done.
iii. The 33 KV winding
- Separate source AC on all the line terminals (routine test)
- Lightning impulse on all the line terminals (routine test)
Note : No separate induced over-voltage test need to be done.
The winding gets tested as a consequence of the induced over
voltage test with partial discharge indication on 400 KV winding.
g)
All tests on OLTC as per cl.16.9 of IS 2026 Part I, IEC 60214.
h)
Measurement of Tan-Delta, Capacitance & IR values of HV,IV,LV &
Neutral bushings before & after tests on transformer
Low voltage AC, magnetic balance and magnetizing current three
phase & single phase at normal tap for field reference. The test shall
be carried out only after ensuring proper demagnetization of the core
so as to achieve proper results.
Measurement of leakage current between core – frame – tank at
rated voltage (during no load loss measurement) and at rated
current (during load loss measurement).
i)
J)
Note : DGA test of oil of main tank of transformer before (initial) & after
completion of all testing shall be done and test results shall be
submitted to the purchaser .
24.2.2
ADDITIONAL ROUTINE TESTS
(A)
Insulation Resistance : Insulation Resistance measurement
shall be done for 15 Secs. , 60 secs. and 600 secs. Duration.
Polarization Index (PI) shall be clearly recorded on test report for
600 sec /60 sec values and D.A.R. for 60 sec/15 sec values.
Minimum preferred IR values for 60 secs at 60oC shall be 1000
M.Ohms.
PI value : PI value (i.e. ratio of IR Values for 600 sec / IR Values
for 60 sec) for winding should be greater than 2.0. This
requirement is to be confirmed specifically by the Tenderers in
their offer.
(B)
Magnetic Circuit Test : After assembly, core shall be tested for 1
minute at 2 KV AC between all bolts, side plates & structural steel
work. Immediately prior to the despatch of the transformer from
works of manufacturer, the magnetic circuit shall be tested for one
minute at 2 KV AC between the Core & Earth and leakage current
shall also be recorded.
(C) Oil Leakage Test on Tank : All Transformer tank with its active part
as assembled for type test (i.e. including pipe work and cooling
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400KV 500 MVA Transformer
equipment and excluding PRV and conservator when air cell is
provided) shall be subjected to a pressure corresponding to twice
the normal head of oil or to normal pressure plus 35 kN/ m.sq.(5psi)
whichever is lower measured at the base of the tank and will be
maintained for 12 hours during which time no leakage shall occur.
Before conducting the pressure test, the following are to be taken
care of :
(i) Pressure relief valve are to be removed and the opening blanked.
(ii) Transformer and tap changer conservators are to be
disconnected.
(iii) Diverter switch compartment of tap changer to be connected
with transformer tank for equalizing the pressure on both
sides.
(iv) Oil should be completely filled and all trapped air released.
(D) Capacitance & Tan-delta Test on winding : The measurement
of capacitance and tan delta to determine capacitance between
winding & earth shall be carried out in mode UST, GST & GSTg both
before and after series of dielectric tests by Ampere turn method.
For temperature correction factors IEEEC 57.90 shall be referred.
For clarity measurement of capacitance and tan delta shall be
carried out as under :
-
HV+IV/LV + Earth (GST)
LV /HV + IV+Earth (GST)
HV+IV/Earth (GSTg)
LV/Earth (GSTg)
HV+IV/LV (UST)
The measured Tan delta values of winding shall not exceed
0.45% at 200C (degree Centigrade) temperature. In case Tan
delta of transformers during testing at works of manufacturer is
measured above maximum ceiling of 0.45% at 200C (degree
Centigrade) temperature, then MPPTCL reserves right not to
accept such of the transformer. This requirement is to be
confirmed specifically by the Tenderers in their offer.
(E)
Test Results of calibration & measurement reports of WTI & OTI ,
ratio test for all CTs and measurement of knee point voltage, IR
value and winding resistance for bushing CT.
(F)
Checking & recording of following:
a. IR values
i.
Between Core and End frame
ii.
Between Core and Tank
iii. Between End frame and main Tank.
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400KV 500 MVA Transformer
The measured IR values should be more than 1000 M Ohms.
This requirement is to be confirmed specifically by the
TENDERERs in their offer.
b. Measurement and recording of currents with application of
400 volts, 3phase, AC supply on HV side with IV side
shorted, as under:
i.
ii.
iii.
iv.
Between Core and Tank.
Between Core and End frame
Between End frame and Tank
Between neutral and short circuited links with neutral
grounded and ungrounded conditions.
NOTE: The details of arrangements provided outside the main
tank for connecting core, end frame and main tank body shall be
indicated on a diagram , to be attached with the test reports.
(G) Test results of CT provided in one phase of tertiary winding
before delta formation.
(H) Magnetizing current measured with LT supply.
No
Particulars
a
b
c
On HV side
On IV side
On LV side
With Single phase supply
Volts.
Amps.
With Three phase supply
Volts.
Amps.
(I)
Magnetic balance test on HV, IV and LV side (before and after
dielectrics).
(J)
Pressure Relief Device Test :All pressure relief devices provided
in each transformer shall be subject to test for its successful
operation. It shall operate before reaching the test pressure
specified in clause 24.3 (B) of this specification. The device shall
seal off after the excess pressure has been relieved.
(K) Frequency Response Analysis (SFRA) Test on Transformer : The
SFRA test shall be conducted by the manufacturer at manufacturers
works using his own SFRA test set and also SFRA test shall be
conducted by the manufacturer at site using same SFRA test set at
the time of erection & commissioning of unit.
(L) Measurement of Dew point prior to despatch of the unit, filled
with N2 gas: Dew point is the temperature at which water vapours
present in the gas filled in the transformer begins to condense. The
transportation of transformer from the factory of manufacturer’s
works upto the purchaser’s site is done with dry Nitrogen gas filled
condition, due to weight limitation. Positive gas pressure say 0.25
kg/cm2 is normally maintained during transportation as well as
during storage. In case positive pressure is not maintained then due
to hygroscopic properties of insulation used in transformer possibility
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400KV 500 MVA Transformer
of absorption of moisture in insulation cannot be overruled.
Therefore to check the dryness of insulation, measurement of dew
point at factory prior to despatch and on receipt of unit at site is
necessary and to be carried out. It may be noted that dew point
shall be measured at factory prior to despatch. Temperature,
pressure and dew point at the time of gas filling (reading taken after
stabilisation) shall be taken and painted on the transformer tank. The
minimum permissible value of dew point shall be (–)25oC at normal
temperature and pressure.
(M) Functional tests on auxiliary equipments i.e. OTI, WTI, valves,
Filters etc as per CBIP publication no 295.
(N) Visual inspection and dimension measurement of transformer
as per approved OGA drawing.
(O) Measurement of rail guage, distance between wheels and
demonstration of rotation of wheel by 90 degree.
(P) Supplier’s test certificate in respect of on line monitoring
(OLMD), NIFPS, pumps & Surge capacitor as per IS,IEC,CBIP
publication no.295.
(Q) Verification of type, material and quantity of valves in line with
Annexure-V.
24.3 TYPE TESTS : Following Type Tests shall be conducted on the transformer
as per IS:2026 Part I, IEC , CBIP publication no 295.
(A) Temperature Rise Test:
This test as per cl. 16.8 of IS:2026(Part- II) shall be conducted at the
lowest voltage tap having maximum current with 10% overload
conditions. The supplier before carrying out such tests, shall submit
detailed calculations showing the alternatives possible, on various
taps and
for
different ratings (ONAN/ONAF/OFAF), of the
transformer and shall recommend the combination that results in
highest temperature rise, for the test. Since 500 MVA transformer is a
auto transformer, the temperature rise test shall be conducted for
the condition of simultaneous loading of all three windings for their
respective
OFAF rating
i.e. 400KV and 220KV winding
corresponding to current of 500 MVA, and 33 KV winding for 105
MVA. Loading on two windings for 500 MVA transformer for the
measured losses will not be accepted. Gas chromatographic
analysis of oil shall be conducted before and after heat run test
and the values shall be recorded in the
test report. The
sampling shall be in accordance with IEC-60567.
For the
evaluation of the gas analysis in temperature rise test, a method will
be proposed which is based on the rate of increase of particular
gases and the permissible limits of minimum detectable value of
gases and the maximum limit will be mutually discussed and agreed
upon between the Purchaser and Supplier. This shall be treated as
reference during maintenance of transformer in future.
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400KV 500 MVA Transformer
The calibration of OTI and WTI shall be done by Transformer
Manufacturer and these calibrated OTI, WTI shall be used during
testing of transformer. The Sr. No. of WTI,OTI shall be recorded
during testing of transformer and these indicators only shall be
supplied with the transformer. During test, manufacturer selects
suitable tap from CT based on gradient between the readings of WTI
& OTI. This tap position is to be clearly recorded on test report so that
selection of correct tap could be done at site to avoid discrepancy in
temperature gradient recorded during factory test and the value
recorded at site.
Tank tests : Following Vacuum and Pressure tests shall be carried
out on one transformer tank of each fabricator:
(B)
(a)
Vacuum Test (Fabrication stage)
Transformer tank of each design shall be subjected to the vacuum
of 760 mm of Hg. The tanks designed for full vacuum (760 mm of
mercury at sea level or the barometric reading at the location of
test) shall be tested at a maximum internal pressure of 3.33 kN/m.sq.
(25 mm of Hg) for one hour i.e. 760-25=735 mm of Hg at sea level
and (Barometric reading -25mm Hg) at other location. The
permanent deflection of flat plates after vacuum has been released
shall not exceed the values specified below:
Horizontal Length of flat plate (in mm)
Up to and including 750
Permanent Deflection (in mm)
5
751 to 1250
6.5
1251 to 1750
8
1751 to 2000
9
2001 to 2250
11
2251 to 2500
12.5
2501 to 3000
16
Above 3000
19
Note :- During Vacuum testing, provision of any kind of internal
supports are not acceptable. This fact is to be kept in
view while finalizing design of tank.
(b) Pressure Test (Fabrication stage)
Transformer tank of each design , its radiator, conservator vessel
,and other fittings together or separately shall be subjected to a
pressure corresponding to twice the normal head of oil or to normal
pressure plus 35 kN/m2, whichever is lower, measured at the base of
the tank and will be maintained for 1 hour during which time no
leakage shall occur. The permanent deflection of the flat plate after
the excess pressure has been released shall not exceed the figures
specified above for vacuum test as per clause 24.3(B)(a).
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400KV 500 MVA Transformer
Note:-
24.4
Permanent deflection both under vacuum and pressure
test shall be within permissible limits separately, as
detailed above.
SPECIAL TESTS : Following special tests other than type and routine tests
shall also be carried out as per IS:2026 Part-I on one transformer.
a) Measurement of zero seq. impedance as per CL.16.10 of IS:2026
Part-I.
b) Measurement of acoustic noise level as per CL.16.12 of IS:2026
Part-I, NEMA TR1 & IEC 60076-10. Detailed calculations & conditions
outlined in the IEEE standard C 57.12.12.90 shall be followed.
c) Measurement of power taken by fans & pumps as per cl.16.14 of
IS:2026Part-I.
d) Measurement of harmonic level of no load current and total harmonic
distortion of voltage & current as per CL.16.13 of IS:2026 Part-I.
Details of rms voltage applied & print out of Harmonic Analyser shall
be enclosed with report.
e) One Cooler Control Cabinet and OLTC cabinet of each design for
each type of transformer shall be tested for IP:55 protection in
accordance with IS:2147 (Category-1) at CPRI/ ERDA.
f) Test to prove over fluxing capability of transformer at over fluxing
factor 1.25.
24.5 To summarize the requirement of tests for 400KV 500 MVA power
transformers covered in this bid specification, are as under :
Number of
transformers to
be tested
1
2
3
24.2.1 Routine tests & On each unit
&
additional routine
24.2.2. tests
24.3
Type test:
(A) Temperature
On One unit of bid
rise test
(B) Vacuum and
On
One
unit
pressure test
/vender
Clause
No.
Nature of tests
24.4
Special tests
On One unit of bid
25
Tests at site
On
each
unit
included in bid
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Test charges
4
Routine tests, additional routine tests
type & special tests and tests to be
carried at site shall be included in the
offered cost.
400KV 500 MVA Transformer
Note : It is to be noted that after complete final testing of the unit , it should
be kept charged at rated voltage for adequate time to ensure proper
demagnetization of core i.e. demagnetization of core shall be ensured prior to
dispatch of the unit.
24.6
Oil to be used by manufacturers at factory for the purpose of testing at
their works shall be of similar or better quality having parameters matching
with the parameters specified in the specification. Specific approval of oil test
results of oil proposed to be used for testing of transformer in factory shall be
obtained by the manufacturer from the purchaser before first filling in the unit.
MPPTCL shall not accept any other oil for testing purposes having lower
parameters than those specified in the tender.
25.0 TESTS AT SITE :On delivery /receipt, after erection at site, the transformer
shall be subject to the following tests, in presence of supplier's engineer.
(i)
Immediately upon receipt of transformer at site and
before
unloading of transformer from trailer, core earthing , end frame
earthing & tank earthing shall be checked . Only after satisfactory
verification that there is no multiple core earthing in transformer,
unloading of transformer shall be undertaken.
ii)
Insulation resistance test and polarization index.
iii)
Ratio and polarity test.
iv)
DGA of oil and Dielectric, Tan-Delta, resistivity & moisture content
test of oil .
v)
OLTC operational test at each tap for lower and raise operation of
tap changer.
vi)
Magnetic balance test and measurement of magnetizing current.
vii)
Vector group test.
viii) Percentage Impedance test at all taps.
ix)
Short circuit current measurement at low voltage and at all taps.
x)
Measurement of winding resistance at all taps.
xi)
Tangent Delta, capacitance and insulations resistance tests of
bushings.
xii)
Leakage current between core & tank, core & end frame , end frame
& tank and between short circuited links & neutral in grounded and
un grounded conditions.
xiii) Dew point measurement & recording of pressure of Nitrogen gas on
receipt of transformer at site on trailer.
xiv) SFRA test
xv) After receipt of transformer at site physical inspection shall be done
for checking any physical damage to transformer tank &
accessories. Further data of Impact recorder shall be analysed for
any changes before unloading of transformer.
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400KV 500 MVA Transformer
26.0 CHECKS & TESTS : Following checks & tests shall be carried out by
Manufacturer at different stages of manufacture & supply of transformer and these
reports shall be sent to the purchaser for records :
(i) Assembled Transformer:
a) Check
completed transformer against approved out line drawing,
provision for all fittings, finish level etc.
b) Jacking test on the assembled Transformer.
c) Measurement and recording of temperature and drying time during vacuum
treatment.
d) Check for completeness of drying by measuring IR values & Tan Delta.
e) Certification of all test results.
(ii) Preshipment Checks at Manufacturer's Works:
a)
b)
c)
d)
e)
Check for interchangeability of components of similar Transformers for
mounting dimensions.
Check for proper packing and preservation of accessories like radiators,
bushings, explosion vent, dehydrating breather, rollers, buchholz relay,
control cubicle, connecting pipes, conservator etc.
Check for proper provision of bracings to arrest the movement of core and
winding assembly inside the tank.
Gas tightness test to conform tightness.
Derivation of leakage rate and ensure adequate reserve gas capacity.
(iii) Commissioning Checks at site :
a)
b)
c)
d)
e)
f)
g)
Check the color of silica gel breather.
Check the oil level in the breather housing, conservator tank, cooling
system, condenser housing etc.
Check the bushings for conformity of connection to the line etc.
Check for correct operation of all protection and alarms.
i) Buchholz relay
ii) Excessive winding temperature
iii) Excessive oil temperature
iv) Low oil flow
v) Low oil level indication
Check for adequate protection on electric circuit supplying the accessories.
Insulation resistance measurement for:
i) Control wiring
ii) Main winding
Check for cleanliness of the Transformer and the surroundings.
27.0 TEST REPORTS : After all tests have been completed seven certified
copies of each test report shall be furnished. Each report shall supply the following
information :i)
Complete identification data including serial number of the
transformer.
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400KV 500 MVA Transformer
ii)
iii)
iv)
Method
of
application, where applied,
duration
and
interpretation of results for each test. Complete diagram of test
circuits and details of test equipments including auxiliary
transformer, Instrument transformer shall be furnished.
Where ever applicable parameters to be corrected to 75º C
temperature.
Test certificates of all the accessories and stage inspections.
28.0 TOOLS : The transformer shall be supplied with a full outfit of tools,
spanners, special tools for assembling and dismantling transformers with a rack
for holding them as per Annexure X. All spanners shall be double ended & case
hardened. The quantity of each item of tools shall be indicated by the Tenderer in
bid.
29.0 DRAWINGS & INSTRUCTION MANUALS
29.1 SPECIFIC REQUIREMENT FOR GENERAL ARRANGEMENT DRAWING:
For our 400KV switch yard, the bay width adopted is 27 metres. Following points
shall be kept in view while finalizing General Arrangement drawing of the
transformer.
ii)
Along transverse direction (i.e. the parallel to the Bushing line) spread of the
transformer from one extreme end to the other extreme end shall be limited
to 27 meters. This spread shall be distributed symmetrically with respect to
the centre line of the transformer ( i.e. 13.5 meters on either sides) This is an
essential requirement to avoid encroachment of the transformer body in the
adjoining bay.
29.2
The drawings for each items of transformer and its accessories are to be
submitted to MPPTCL at the time of obtaining approval of manufacturer.
29.3
As soon as possible after the award of the contract (preferably within 15
days), the manufacturer shall supply four (4) copies of the drawings as listed in
Annexure VII (duly bound in suitable plastic folder), which will describe the
equipment in details for approval and shall subsequently provide ten complete
sets of final drawings (duly bound in suitable plastic folder) , one of which shall be
auto-positive suitable for taking blue prints. Also after the award of the contract
the manufacturer shall supply Instruction Manual. This Instruction Manual shall
be hard bound manual shall contain set of all approved drawings, instruction
books, manufacturer’s catalogue of all bought items & fittings, operation &
maintenance manuals , spare part bulletin
(a)
Two copies of each drawing mentioned above and Instruction Manual
shall be sent along with the transformer & its accessories to site. Further a CD
containing soft copy of all drawings in AutoCAD , instructions manuals and
other relevant details in acrobat or MS word shall be sent with transformer to
site . This CD shall contain AutoCAD software and acrobat reader software
also.
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400KV 500 MVA Transformer
(b)
Ten (10) sets of hard bound folders containing copies of approved
drawings, instruction manuals shall be sent to order placing authority within a
fortnight of approval of drawings. Further, Six (6) CDs containing soft copy of
all drawings in AutoCAD , instructions manuals and other relevant details in
Acrobat or MS word shall be sent to order placing authority. These CDs shall
contain AutoCAD software and acrobat reader software also.
30.0 The offered price shall include cost of drawing / manuals as detailed out
in Annexure VII.
31.0 QUALITY ASSURANCE PROGRAMME : The Tenderers must establish that
a proper quality assurance program is being followed by them for manufacture of
power transformers. The quality Assurance Program must have a structure as
detailed in the following paragraphs.
31.1 Customers Specifications And Contract Review : The quality assurance
and failure prevention starts with careful study and scrutiny of our technical
specifications and requirements. The supplier shall carefully study all the technical
parameters and other particulars & the supplier shall categorically give his
confirmation that these requirements shall be met in a satisfactory manner.
31.2 Design Control : The supplier shall furnish the checks exercised in
design calculations particularly in respect of short circuit forces and method of
clamping end coil to show the healthiness of the design. The salient features of
design together with the certificates of design engineers will have to be made
available to the Purchaser.
31.3 Engineering Documents :The supplier shall give complete information
regarding copper conductor, insulating paper, core materials, tap changer, gaskets
etc. bringing out the detailed description and specification of these items with
explanation as to how our requirements are being met in this respect.
31.4 Procurement Document Control & Purchased Material & Services:
The supplier shall indicate the various sources of the items namely copper
conductor, insulating paper, core material, tap changer and other items such as
gaskets etc. are being procured. The type of checks, quantum of checks and
acceptance norms shall be intimated and random test and check results should
be made available for inspection whenever so desired. The vendor for various
bought out items should be as per list indicated in Annexure-VI only. No change in
vendor list shall be acceptable after placement of order. Only in case of difficulty in
getting timely supply from approved vendor, supplier may submit request for
inclusion of only one additional vendor alongwith requisite details pertaining to
Experience/performance/supply capacity/ their own experience etc. However,
Employer decision to accept or not to accept such request shall be final and binding
on the suppliers. Therefore, suppliers are requested to take timely action for
arranging delivery of complete bought out items so as to avoid such situation.
Furnishing of following certificates is essential:-
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400KV 500 MVA Transformer
i) Certificate and proof in the form of bill of lading for purchase of core
material either directly from abroad manufacturers or their accredited
selling agent.
ii)
Certificate and proof in the form of bill of lading for purchase of EC
grade copper from National & International reputed manufacturers or
from their accredited selling agents.
It will however be obligatory on the part of Tenderer to allow third party
inspection of all important material e.g. copper, core material, Insulating cylinder
etc. Tenderer shall furnish certificate that the transformer shall be manufactured
with the input material approved by the Purchaser and in case during
independent third party inspection any of the above material is found different than
from approved list of vendors, in that case Purchaser reserves the right to
summarily reject complete transformer and the manufacturer has to replace
complete unit made out from all input material from the vendors approved by the
Purchaser.
31.5 Programme Chart : Based on above QAP and offered delivery schedule a
tentative program chart indicating period for various manufacturing/testing
activities shall be submitted along with QAP . The program chart should specify
periods for various activities i.e. design, ordering of new materials, assembly,
testing etc.
It should be noted by the Tenderers that submission of QAP by successful
Tenderer is an essential requirement.
32.0
INSPECTION AND TESTING
32.1
Inspection
32.1.1 The Purchaser shall have access at all times to the works and all other
places of manufacture where the transformers are being manufactured and the
Tenderer shall provide all facilities for unrestricted inspection of the Tenderer’s
works, raw materials, manufacture of all the accessories and for conducting
necessary tests as detailed herein.
32.1.2 The successful Tenderer shall keep the Purchaser informed in advance of
the time of starting and of the progress of manufacture of equipment at its
various stages of manufacturing, so
that arrangements could be made for
inspection.
32.1.3 No material shall be dispatched from its point of manufacture unless
the material has been satisfactorily inspected and tested.
32.1.4 The acceptance of any quantity of Transformer & its accessories shall
in no way relieve the successful Tenderer of his responsibility for meeting all the
requirement of this specification and shall not prevent subsequent rejection if such
equipments are later found to be defective. Acceptance of condition regarding
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400KV 500 MVA Transformer
stage inspection at various stages which will be intimated to successful Tenderers
shall be the essence of the contract to be placed against this TENDER.
32.2. Inspection Programme : The Tenderer shall chalk out a detailed inspection
and testing program for manufacturing activities for the various components. An
indicative program of inspection as envisaged by the Purchaser is given in
Annexure-IX. The Purchaser reserves the right to get carried out any tests by a third
party. All Cost of inspection/tests shall be borne by the Tenderer. Readiness of
stage/final inspection be intimated in 15 days advance so as timely deputation of
inspecting officer could be ensured.
32.3
Stage Inspections
32.3.1 The supplier shall indicate the inspections and checks carried out at
various stages of the manufacture of the transformers. A complete record of
stage inspection would be kept by the supplier and this record should be made
available for inspection by the representative of the Purchaser. The supplier should
indicate the manufacturing program and the Purchaser will have a right to
depute its inspecting officers during the manufacture. Some of the inspecting
stages are tank during fabrication, coil winding , core building, assembly of coil on
core, the condition of the coil and core after the treatment in vacuum chamber,
assembly within the transformer tank together with application of tap changer.
32.3.2
It may be noted that stage inspection for first unit or all the units ,at our
discretion , shall be done by us at the following stages.
(a)
Fabrication stage of tank: After fabrication, tank shall be inspected for
measurement of its dimensions, thickness of sheets used , leakage test by applying
requisite pressure/vacuum and water logging test.
(b)
Building up of Core : After the core is built but before its clamping, our
representative will inspect the core to take complete weight of the core and
also to measure approximate core loss. If necessary, a small strip of core shall
also be taken for testing at CPRI, Bangalore or at any other testing lab of repute.
(c)
Preparation of Winding : Once the coils are prepared but before the
same are fitted on to the core, stage inspection shall be done to take various
measurements and also for weighment of total weight of coil of each voltage class.
Measurement of resistance shall be taken and for this purpose, a small piece of
conductor for each type of winding shall be made available by the manufacture.
(d)
Core Coil Assembly Before & After VPD.
The Successful Tenderer has to submit with the bid complete details of
Drying out process of transformer adopted in its works. The details
should include cycle, description , termination rate , process diagram ,
size of oven , measurement method of moisture extracted etc .
,
Apart from the above, the Purchaser also reserves the right to carry
out stage inspections at other stages also, for which advance intimation shall
be given and all necessary cooperation shall be rendered by the manufacturer.
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400KV 500 MVA Transformer
32.4
Final Inspection and Testing
32.4.1 At the time of final inspection, the supplier shall identify each and every
item/accessories/fittings of the particular transformer under testing. Unless all the
items are identified, the manufacture will not be treated as complete. Serial number
of bushings, serial number of tap changer and other accessories shall be entered
into the test report to ensure that the same are supplied with the transformer.
Various tests stipulated in IS shall be performed in the presence of purchaser’s
engineers or when the inspection waiver has been given, in such a case, the
testing shall be done at the manufacturer’s works as per IS stipulations and
same should be confirmed by documentary evidence by way of Test Certificate
which shall be got approved by the purchaser.
32.4.2 The WTI & OTI shall be calibrated during testing of transformer and
Serial Nos. of these instruments shall be recorded in test reports. The WTI & OTI
used during testing shall be dispatched with the transformer so that installation of
same OTI & WTI on transformer is done which are utilized during testing of
transformer at suppliers works. The Bushings and Radiators on Transformer (if
heat run test is conducted ) during testing of transformer at manufacturers works
are required to be supplied with the same transformer to avoid any mismatch /
misalignment etc. during assembly of transformer. This should be noted for strict
compliance and confirmed specifically.
32.4.3
Whenever inspection call for a particular transformer is given, the letter of
inspection call will accompany the following:
33.0
a.
List of various fittings and accessories which are ready at the works
and will be offered for inspection. The Inspecting Officer will carry
the list and check the items declared to have been offered for
inspection .
b.
It is expected that before a transformer is finally offered for
inspection, internal testing of the transformer for various
important parameters like winding resistance, transformer losses,
IR values etc are already done. Routine test report for such tests
shall also accompany the letter of inspection call so that the
Inspecting Officer at the time of inspection may verify the
parameters brought out in the preliminary report. Details of all
tests should be clearly brought out.
c.
In case for any reasons inspection is not completed or
equipment is not found to be complete with all accessories as per
confirmation given with the letter of inspection call, the Purchaser
will reserve the right to recover the complete cost of deputation of
inspecting team to the works of the manufacturer.
STORAGE, HANDLING & SHIPPING:
When the transformer is declared ready, the manufacturer has to identify
each and every item associated with this unit and a `Complete Packing List shall be
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400KV 500 MVA Transformer
prepared in advance. The equipments shall be stored and handled properly in
shipping depot, while the same is under process of dispatch. The manufacturer
should ensure dispatch of all the related items and accessories with a particular
unit of transformer along with tank.
Tap changer, bushing, radiators and other accessories of the transformer
should not be withheld for use subsequently on units for testing purposes. If there
are any items procured from sub-contractors which are to be directly installed like
instrumentation, panels, control gear etc. test and inspection report for the same
shall be kept separately and made available to purchaser’s inspecting officers.
It may be noted that NO CHANGE in any accessory or associated
equipments after passing all the test successfully shall be allowed and if this is
subsequently detected it shall be binding on the Tenderer to replace with the same
item with which the initial test were conducted at his part failing which the entire
test shall become null and void. The Purchaser at his discretion may consider for
rejection of the units thus supplied. The entire cost, for replacement of such rejected
units thus supplied and for repeating acceptance test, shall be borne by the
Tenderer.
34.0
COMPLETENESS OF EQUIPMENT AND BOUGHT OUT ITEMS
34.1 A list of all the accessories which will be supplied with the transformer
should be as per Annexure II & III.
34.2 It is obligatory on the part of Tenderer to ensure that supply of all
accessories as per Annexure-II are made alongwith Main Tank or prior to delivery of
Main Tank so that erection and commissioning work of Transformer can be
completed properly and uninterruptedly .The date of supply of last accessory will
be treated as date of delivery of transformer and penalty shall be imposed upto a
maximum of 10 % for delay in supply and supply bills will be processed
accordingly.
34.3 The responsibility for obtaining timely supplies of bought out items will rest
on the Tenderer and only on this basis, delivery period will be offered in the
tender.
34.4 It may be noted that in case of damages/shortages due to improper packing
or any other negligence ,replenishment shall be arranged within one month of
being noticed by the purchaser. If this is not done, date of delivery of such
accessory will be treated as date of delivery of main equipment and full penalty
shall be recoverable from the Tenderer on total cost of the equipment. This
should be confirmed.
34.5 For bought out items, responsibility for guarantee and obtaining immediate
replacement in case any defects are noticed and in case defective supply of any
item is reported will rest on the Tenderer.
34.6 In case for attending to defect in any accessory or inspection/ replacement of
the accessory, which may be bought out item
for the Tenderer; services of
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75
400KV 500 MVA Transformer
engineer of original manufacturer is required, the same will be organized on
immediate basis by the Tenderer at his cost.
34.7 The Tenderers are required to furnish, the following details of packages for
supply of complete quantity of materials/one complete equipment:
i.
Total number of packages
ii.
Dimensional details of each package.
iii. Weight of each package.
iv.
Nature of content (i.e. fragile or non-fragile)
In addition, the Tenderer from outside India offering CIP prices shall also
indicate the port of entry in India.
35.0 For all power transformer included in the bid specification , provisions and
stipulations as per CBIP Manual on Transformers in regard to the following except
as modified in this document should be strictly adopted
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
k)
l)
m)
n)
o)
p)
q)
r)
s)
t)
u)
36.0
Design and authorization.
Galvanising.
Labels.
Nuts & bolts.
Cleaning & Painting.
Prevention of acidity.
Continuous maximum rating & over loads.
Duty under faults conditions for stabilizing windings.
Flux density and magnetizing current.
Vibration & noise.
Suppressions of harmonics.
Magnetic circuit and mechanical construction of cores.
Constructional arrangements for winding.
Earthing arrangements.
Cooling plant for the transformers.
Temperature indicating device and alarm.
Gas actuated relays.
Marshalling box/control cubicle, panel drives & Mechanism Box
Control connection and instrument wiring.
Drying out, transport and erection.
Valves and air release plugs.
REQUIREMENT FOR TRANSPORTATION OF TRANSFORMERS
Two nos. Electronic impact recorder (on returnable basis) in diagonally opposite
position to eliminate changes of loss of data to failure of recorder during
transportation to measure the magnitude and duration of the impact in all the three
direction. The acceptance criteria and limits of impact in all three directions which
can be withstood by the equipment during transportation and handling shall be
submitted by the supplier during detailed engineering.The recording shall commence
in the factory before despatch and must continue till the unit is installed on its
foundation. The data of electronic impact recorder(s) shall be down-loaded at site
and a soft copy of it shall be handed over to Engineer-incharge. Further, within three
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400KV 500 MVA Transformer
weeks the supplier shall communicate the interpretation of the data. In the unlikely
event of impact recorder output not available at site, the equipment shall be
thoroughly internally inspected by the manufacturer’s representative before erection
at site to ensure healthiness of the equipment.
Further the supplier shall mount Vehicle tracking system (GPRS/ GPS/ GSM
based) to track the exact position of the vehicle on which the Autotransformer is
being loaded for transportation and during detailed engineering take approval for the
equipment installed.
Note :- No charges shall be payable for installation of electronic impact
recorder & vehicle taking system during transportation while quoting
transportation charges, this aspect is to be kept in view.
37.0
THE DETAILS FOR ONE SET OF ESSENTIAL MAINTENANCE
MANDATORY SPARES/EQUIPMENTS TO BE SUPPLIED ALONGWITH
EACH TRANSFORMER:
S.
Essential Maintenance/Mandatory Spares/Equipments to
No. be supplied with each transformer.
1
420 KV RIP bushing (Meeting technical specification stipulated in
clause 11.13)
2
245 KV RIP bushing (Meeting technical specification stipulated in
clause 11.13)
3
72.5 KV RIP bushing (Meeting technical specification stipulated in
clause 11.13)
4
Terminal connector each for HV, IV & LV bushings suitable for
double/double/single Moose ACSR (31.77 mm) conductor .
(Meeting technical specification stipulated in clause 19.0)
5
5 KV digital Insulation Tester (Meeting technical specification
stipulated in clause 37.2.1)
6
Capacitance & Tan delta measurement kit (Meeting technical
specification stipulated in clause 37.2.2)
7
BDV test kit (Meeting technical specification stipulated in clause
37.2.3)
8
Winding Resistance Measurement kit (Meeting technical
specification stipulated in clause 37.2.4)
Quantity
1 No.
1 No.
1 No.
1+1+1 No.
4 No.
4 No.
1 no.
1 no.
37.2 TECHNICAL SPECIFICATION FOR TESTING EQUIPMENT :The offered Testing equipments shall have technical particulars generally conforming
to the requirement of the latest version of relevant standard of International ElectroTechnical Commission (IEC) or equivalent National Standards of India. Bidders shall clearly
state the standards to which the equipment offered by them conforms.
37.2.1 TECHNICAL SPECIFICATION FOR 5 KV INSULATION RESISTANCE TESTERS:The 5 KV digital Insulation Tester shall be compact, lightweight, 3 digit digital insulation
tester. The 5 KV digital insulation tester shall be compact, lightweight, 3 digit digital
insulation tester. The Insulation Tester shall be supplied with suitable software in form of
CD/DVD to allow for further analysis of tests results, including features such as graphical
representation and automatic report generation. The Insulation Tester shall provide safe,
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400KV 500 MVA Transformer
reliable and accurate measurements of insulation resistances up to 10 TΩ, with selectable
test voltages, 250 V – 5 kV in steps of 50V.
The operation of Insulation Tester shall be microprocessor controlled and it shall have
features such as auto-range selection, memory for 1000 readings, AC/DC voltmeter,
automatic measurement of Insulation Resistance, Dielectric Absorption Index, Polarization
Index, Dielectric discharge test, Breakdown Voltage Test, Step voltage test, leakage current
and capacitance measurement. Timer enabling programming of test duration, & real time
clock shall be provided. Built-in chronometer, indicating remaining time in minutes and
seconds, since the test started, up to 99 minutes.
It shall be possible to transmit Measured values through the isolated serial output (RS-232).
Storage of about 1000 measured values in a non-volatile internal memory which can be
transferred to a PC and the supplied software by Insulation Tester shall allow further
analysis of the test results, including a graphical representation & automatic report
generation. The real time clock, and the sequential test number, shall facilitate the
identification of each test, and the organization of a predictive maintenance system by trend
analysis.
The Insulation Tester shall be powered using a rechargeable battery and supplied with an
automatic inbuilt charger operating on 240 V +- 10% , 50Hz mains supply. The battery
backup shall not be less than 5Hours of typical use with fully charged battery. The cabinet of
Insulation Tester shall be IP 65 rated, strong, lightweight, easy to carry, impact-resistant and
suitable to be used under severe weather conditions.
The instrument must be IEC 61010-1 to 600V phase to earth, Category IV and IP54
Protected.
37.2.1.1 FEATURES:
• Microprocessor-controlled
• Insulation resistances up to 10 TΩ
• Auto-range
• Digital & bar-graph reading
• Tests Regimes:
• Absorption index
• Polarization index
• Dielectric Discharge
• Step Voltage Test
• Breakdown Voltage Test
• Capacitance
• Leakage current
• AC/DC voltmeter
• Chronometer up to 99 minutes
• Real time clock
• 1000 readings memory
• Isolated RS-232 data port
• Software for data management
• Rechargeable battery Selectable
• Selectable test voltage of 250 & 5000 V DC in steps of 50V.
• The Insulation Tester should have self-calibration checkup at every startup.
• The Insulation Tester shall be equipped with High Voltage terminal, Measurement
& Guard terminal. These terminals shall be suitably marked for easy identification.
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400KV 500 MVA Transformer
• The Insulation Tester shall be equipped with audio & visual indication for the test
ON condition.
• The Insulation Tester shall discharge the test object after every test.
• The Insulation Tester should have three programmable timers for conducting
diagnostic tests.
•Instrument should have Dual Power supply, Battery and hand-crank
generator. Both power supply should be available at the same time without a
need to disassemble it.
37.2.1.2 Accessories to be supplied with each 5 KV Insulation Tester:a.
b.
c.
d.
e.
f.
g.
h.
i.
j.
2 x Measuring test leads (IEC 61010-031)
1x GUARD test lead
Charger power cord
Software CD
RS-232 cable
Protective bag
Operating instructions
software
Test & calibration sheet.
Fuses
37.2.1.3 The Insulation Testers shall be suitable for insulation measurements during
installation, servicing and maintenance work in charged substations. The instrument shall
be suitable for testing Transformers, Switch Gears, relays, switches and contactors. The
preferred vendor for 5 KV Insulation Testers shall be Megger/ Motwane make.
37.2.1.4
No.
Technical Particulars:Particulars
Requirement of 5 KV Insulation Tester
1
Resistance
2
Output Voltages
Max 10 TΩ @ 5 kV
± 5 % of reading up to 1 TΩ @ 5 kV
± 20 % of reading up to 10 TΩ @ 5 kV
Selectable test voltage of 250 & 5000 V DC in steps of 50V.
3
4
Current
Input Power
3mA
230V AC±10%, 50Hz±10%
5
6
Response Time
Display
7
Display Update
Over Range
Indication
Environment
< 15 seconds
3 digit LCD, 1000 counts
Current battery status
2.5 readings/sec
“>” is displayed in most significant digit
8
Physical
Volume-II
(a) Operating Temperature Range : 0 ºC to 60 ºC
(b) Storage Temperature Range -10 ºC to 60 ºC
(c) Humidity Range
95% RH (non condensing)
(d) Environmental Protection: IP 65 (with closed lid)
(e) Safety Class Meets the requirements of IEC 61010-1
(f) E.M.C: In accordance with IEC 61326-1
(g) Type tested as per IS 11994
(h) CE marking
5 kg (Approx)
79
400KV 500 MVA Transformer
37.2.1.5 TRAINING: Subsequent to delivery of 5KV Insulation Testers, demonstration &
Training for 1 to 2 days period to a batch of our engineers shall be provided by the supplier
on “free of cost” basis for each Equipment supplied by the supplier. The training shall cover
operation, evaluation/analysis of test results and general trouble shooting about the
equipment.
37.2.1.6 SCOPE OF SUPPLY : Each 5KV Insulation Testers shall consist of following
- 5KV Insulation Tester in rugged case
- Accessories – Kit should be supplied with IEC 61010-031 complied 2 sets of
measuring leads out of which one 2-3 Meter long and the other 8-10 meter long testing
leads. With maximum jaw opening span of 40mm, software CD, RS232 Cable,
- Operating instruction &Test Certificate
37.2.1.7 Any other item or accessories, which are essentially required for satisfactory
operation of equipment & for meeting requirements of this specification shall be
deemed to be within scope of the Tenderer irrespective of whether these are
specifically indicated here or not.
37.2.1.9 TECHNICAL REQUIREMENT OF 5 KV INSULATION TESTER:No.
Particulars
Requirement of 5 KV Insulation Tester
1
Resistance
Max 10 TΩ @ 5 kV
± 5 % of reading up to 1 TΩ @ 5 kV
± 20 % of reading up to10 TΩ(for lower test
voltages, the upper limit will be reduced
proportionally)
2
Output Voltages
250V to 5000V in steps of 50V
3
4
Current
Input Power
3mA
230V AC±10%, 50Hz±10%
5
6
Response Time
Display
7
Display Update
Over Range
Indication
Environment
< 15 Seconds
3 digit LCD, 1000 counts
Current battery status
2.5 readings/sec
“>” is displayed in most significant digit
8
Physical
Volume-II
(a) Operating Temperature Range : 0 ºC to 60 ºC
(b) Storage Temperature Range -10 ºC to 60 ºC
(c) Humidity Range
95% RH (noncondensing)
(d) Environmental Protection: IP 65 (with closed
lid)
(e) Safety Class Meets the requirements of IEC
61010-1
(f) E.M.C: In accordance with IEC 61326-1
(g) Type tested as per IS 11994
(h) CE marking
5 kg (Approx)
80
400KV 500 MVA Transformer
37.2.2 TECHNICAL SPECIFICATION OF FULLY AUTOMATIC CAPACITANCE &
TAN DELTA MEASUREMENT KIT :I.
Functional Requirement:1. The instrument should be suitable for automatic offline measurement of
Capacitance & Tan Delta of the switchyard equipments as well as excitation
current of transformers/ reactors, in live switchyard upto 400 KV level, as per
applicable standards and testing procedure of MPPTCL.
2. The test results should have repeatability, consistency & immunity to
electromagnetic interference in live switchyard upto 400KV level.
3. The measurement of ambient temperature & relative humidity which
inbuilt/external arrangement.
4. The instrument should be suitable to measure tan delta and capacitance in
UST, GST, GSTg mode
5. The test kit should have sinusoidal frequency generator
6. The test kit should have frequency modulation technologies for interference
suppression
7. The test kit has measuring principal R-L-C
II. Out Put:
1. V: 0-12KV AC Continuously
2. I : 0-100mA (Min) continuous, 300mA(Min) intermittently
III. Test Frequency:
15Hz to 400Hz, Independent of line voltage & frequency variations.
IV. Accuracy:
1. Capacitance: <0.5% of reading ± 1pF
2. Tan delta : <0.5% of reading ± 0.02%
V. Measurement Range:
1. Capacitance: 1pF to 3µ F
2. Tan delta : 0 to 10000%
VI.
Test Leads and Accessories: One complete set of cables of sufficient length
(Min 20 metre) with suitable clamps & connectors, compatible with the
instruments should be provided for successfully carrying out the test in MPPTCL
S/S. Additionally all the required accessories, drawing & documents, tools etc.
should be provided for the smooth functioning of kit. Original carrying case which
should be robust / rugged enough, for ensuring proper safety of the kit during
transportation shall have to be provided.
VII.
Design/Engg.: The complete equipment alongwith complete accessories must
be designed / engineered by original equipment manufacturer
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400KV 500 MVA Transformer
VIII. Power Supply: It shall work on single phase 100-240 Volts , 50Hz ± 5% supply
with standard socket.
IX.
Operating Temperature: 0 to + 50 deg C
X.
Relative Humidity: Max. 90% non-condensing
XI.
Protection/Control: Against short circuit, over voltage, improper ground
connection over load & transient surges, the kit should have alarm/cut-off features
with magnetic overcurrent tripping at I> 16 Amp to protect the instrument. Also
the kit should have facility of stopping automatically on power failure as well as
interlock for HV.
XII. Cooling Arrangement: Necessary in built cooling arrangement should be
provided to dissipate the heat generated during testing, No external
coolant/accessory shall have to be required.
XIII.
Weight: It should be easily portable and trolley mounted for smooth movement
in live switchyards
XIV.
Software: The software should be suitable for automatic test report generation
and trend analysis. The kit should have facility to store and communicate with
windows based computer for exporting the test data.
XV. Display /Control: It shall include supply of one laptop PC of Dell/Lenovo/HP
make with latest specifications such as Core i5 Intel Processor, 4GB RAM,
320GB or better HDD, 15” TFT screen, Combo DVD Drive i.e having CD
read/write facility Window 10 professional or better with latest version of
application software required for storage, analysis and record management . If
kit is being controlled through inbuilt LCD monitor and kit is having data storage
facility, then there is no need to supply laptop.
XVI.
Environment: The test kit shall be compatible for EMI/EMC/safety environment
requirement as per IEC.
XVII. Calibration Certificate: Unit shall be duly calibrated before supply and the date
of calibration shall not be older than two month from the date of supply of kit.
XVIII. Training: Supplier shall have to ensure that the kit is made user friendly. Apart
from the detailed demonstration at site, the supplier shall also have to arrange
necessary training to MPPTCL engineers.
XIX.
Commissioning, Handing Over the Instrument: Successful tenderer will have
to commission the instrument to the satisfaction of MPPTCL. The instrument
failed during the demonstration shall be rejected and no repairs are allowed.
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400KV 500 MVA Transformer
XX.
After Sales Services: Tenderer will have to submit the documentary evidence
of having established mechanism in India for prompt after sales services.
XXI. Accessories: Any other item or accessories, which are essentially required for
satisfactory operation of equipment & for meeting requirements of this
specification shall be deemed to be within scope of the Tenderer irrespective of
whether these are specifically indicated here or not.
XXII. The preferred vendor for Capacitance & Tan Delta kit shall be Megger/
Omnicorn make.
XXIII. It may be noted that free training facility will have to be provided to two batches
of our Engineers/ Technicians. Each batch will consist of 4 Engineers and 4
Technicians and the period of training shall be around one week. During the
period of training, our staff/officers will be trained in regard to design, assembly,
erection, commissioning and maintenance of the equipments. This facility will
have to be provided on “Free of Cost” basis, although necessary
accommodation and boarding charges and to and fro fare charges for our
personnel to manufacturer works will be to our account.
37.2.3 TECHNICAL SPECIFICATION FOR DIELECTRIC STRENGTH OF OIL
(BDV)TEST KIT :1.1
This specification covers the design, manufacture, stage testing,
inspection and testing before dispatch, packing and delivery of Dielectric
Strength of Oil (BDV) Test Kit in the state of Madhya Pradesh for 400kV, 220kV
and 132kV Transmission Substation. The offered equipment shall be of
reputed make, type tested and shall be subjected to acceptance & routine
tests in accordance with relevant standards, as applicable.
1.2
It is not the intent to specify completely herein all the details of design
and construction of Dielectric Strength of Oil (BDV) Test Kit. However, the
offered Dielectric Strength of Oil (BDV) Test Kit shall conform in all respect to
the high standard of design, workmanship and shall be capable of performing
the duties specified herein. The Dielectric Strength of Oil (BDV) Test Kit shall
be robust, rugged in design so that these can be used even in adverse site
conditions. In the event of bidder offering equipments manufactured by
different manufactures, it will be responsibility of the bidder to fully coordinate
the activities of each manufacturer in such a way that the complete offered
equipment is manufactured, supplied & guaranteed for successful operation.
1.3
All the materials used for the manufacture of the Dielectric Strength of Oil
(BDV) Test Kit shall be of the best quality and the design, workmanship shall be of
the highest order, so as to ensure satisfactory operation over its full life. The
Dielectric Strength of Oil (BDV) Test Kit shall complete with all components &
accessories necessary for their effective and trouble-free operation for meeting
technical requirement stipulated herein below. Such components and accessories
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400KV 500 MVA Transformer
shall deemed to be within the scope of supply, irrespective of whether these are
specifically brought out in this specification or not.
STANDARDS:
2
2.1
Unless otherwise mentioned in the specification the offered Testing
equipments shall be manufactured, tested and supplied with all guaranteed technical
particulars generally conforming to meet the requirement of the latest revisions of
relevant standard of International Electro-Technical Commission (IEC) or equivalent
National Standards of India (IS). Bidders shall clearly state the standards to which
the equipment offered by them conforms. In the event of offering of equipment
conforming to standards other than IS, the salient points of comparison between
standards adopted and the relevant IS shall be indicated in the proposal alongwith
copies of adopted standards. It will be sole responsibility of the bidder to prove that
the salient features of offered equipment are equivalent or better than standards
specified above.
3
CLIMATIC CONDITIONS:
The offered equipments / materials shall be suitable for continuous
satisfactory operation under climatic conditions listed below:
S.
No.
1
Particulars
Conditions
Location
2
3
4
5
Maximum ambient air température
Minimum ambient air température
Average daily ambient temperature
Maximum Relative humidity
6
Average number of thunderstorm
days per annum
Average No. of rainy days per annum
Average annual rainfall
Months of tropical monsoon condition in
the year
Maximum wind pressure
Altitude not exceeding
Seismic level(Horizontal acceleration)
7
8
9
10
11
12
Outdoor In the state of Madhya
Pradesh
500 Centigrade
-10 Centigrade
300 Centigrade
95%
(sometime
approaches
saturation)
50
90
125 cm
June to October
150 Kg/m2
1000 Mtrs
0.3 g
Note: Moderately hot and humid tropical climate, conducive to rust and fungus
growth. The climatic conditions are also prone to wide variations in ambient
conditions. Smoke is also present in the atmosphere. Heavy lightning also
occurs during June to October.
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400KV 500 MVA Transformer
4
SYSTEM PARTICULARS:
The equipment/materials offered under this specification shall be used in the
substations having following system parameters:
S.No
PARTICULARS
1
2
3
4
5
6
Nominal system voltage
Highest system voltage
Frequency
Number of phases
Earthing
Basic insulation level (Kv
peak)
5
SYSTEM PARAMETERS
765KV 400 KV 220KV
132KV 33KV
765KV 420 KV 245KV 145KV 36 KV
-----------50HZ---------------------------------------Three------------------------------Effectively earthed------------1550 1425
1050
630
170
TECHNICAL SPECIFICATION FOR DIELECTRIC STRENGTH OF OIL
(BDV) TEST KIT :-
An Oil breakdown voltage test set is used to measure the dielectric voltage
withstanding capacity of insulating oils between a specified gap between electrodes.
An automatic Oil BOV test set shall work according to pre-programmed national and
international test standards and provide repeatable and consistent breakdown
values, and automatically average them.
1. The instrument should have step less/continuous voltage incrementing ability
from 0 to 100kV. User should be able to use as a breakdown test set or as
withstand test set.
2. The instrument should have a large graphic backlit LCD display with
membrane keypad or 5’’ touch-screen display for user interface.
3. The instrument should have option to set Initial Hold time, Stir time, and
Intermediate Hold time, each for 99 mins with resolution of 1 sec. Stirring
should be non-contact magnetic type.
4. The instrument shall have internally pre-programmed national and
international test standards related to Oil BOV testing, for convenience of
user. There should be further ability for the user to program a customized test
sequence as when may be required.
5. The instrument shall be internal non-volatile memory for storage of test data.
Facility should be provided to download them on PC via USB communication.
It should be also possible to print the test results on an integrated panel
printer on the test set.
6. The instrument should have necessary interlocks and protection for user
safety. Important among them being, Earth missing, Phase-Neutral reversal,
HV chamber door open, Zero start interlock etc.
7 The instrument should be portable & light weight. It should not weight more
than 35 Kgs. The body of the instrument shall be of powder coated SS grade
steel to avoid corrosion even after years of usage in high moisture
conditions.
8. Additionally a Industrial grade Carrying case must be provided with the
instrument.
9. The oil vessel supplied with the instrument should be made of Polycarbonate
or of Acrylic, and should be able to fill in 350-500ml of Oil. The electrode gap
will have to be adjustable and gap gauges suitable for various standards
need to be provided. Electrodes suitable to various standards like Mushroom,
Volume-II
85
400KV 500 MVA Transformer
Cylindrical and Spherical also to be provided as part of supply
10.The instrument should work on 230V AC +/- 10%. Test frequency should be
same as line frequency, of 50 Hz
11. Instrument should have facility to record ambient temperature and humidity
and record the same in test result printout
12 Test result printout should have the standard deviation, min BOV, max
BOV and average BOV noted in it
13 . It should have power consumption less than 500VA.
14. It must operate reliably for temperature from 0°C to 50°C and up to 95% RH
(non-condensing)
15 It should be supplied with carrying case for Oil Vessel and other accessories.
16.The instruction manual and calibration certificate having traceability to NABL
accredited lab should be supplied alongwith the instrument
17. Supplier shall have to ensure that the kit is made user friendly. Supplier has
to impart training to substation engineers on proper operation/utilization of kit.
18.A Suitable calibrator should be provided with the set of calibration meter
suitable for verifying the calibration of oil test sets upto 100 KV.
19.The preferred vendor for BDV kit shall be Motewane / Shivnanda make.
6
GENERAL REQUIREMENTS:-
6.1
SUPPLY SOURCE:- It shall be capable of being operated from 230/250V, 50
HZ, single phase AC supply and shall be completely portable. It shall also work from
inbuilt battery with battery charger.
6.2
TYPE OF CONSTRUCTION:- The construction shall be suitable for use of
indoors as well as outdoors with minimum operational problems.
7.0
TRAINING:- It may be noted that free training facility will have to be provided
to two batches of our Engineers/ Technicians. Each batch will consist of 4 Engineers
and 4 Technicians and the period of training shall be around one week. During the
period of training, our staff/ officers will be trained in regard to design, assembly,
erection, commissioning and maintenance of the equipment. This facility will have to
be provided on “Free of Cost” basis, although necessary accommodation and
boarding charges and to and fro fare charges for our personnel to manufacturer
works will be to our account.
37.2.4
TECHNICAL SPECIFICATION
RESISTANCE METER:I.
OF
TRANSFORMER
WINDING
Functional Requirement:1. The instrument should be suitable for offline measurement of winding
resistance of transformer, including OLTC and reactors etc. upto 400KV in
live switchyards upto 400KV level, as per applicable standards/testing
procedure.
2. It should have min. 03 No. measuring channels for Winding Resistance, 1 for
Test Current measurement and 1 for external temperature input
3. The test results should have repeatability, consistency & immunity to
interference in live switchyard upto 400KV levels
4. The instrument should be work on 4 wire measurement method.
Volume-II
86
400KV 500 MVA Transformer
II.
Test Current: 25A DC continuous current with selectable current range facility in
the range of 10mA, 100mA, 1A, 5A, 10A, 25A.
III.
Measurement Range: 0-2000 Ω, Auto Ranging. The instrument shall be
capable of measuring resistance upto 800 milli – ohms at 25 Amp current and
upto 2 ohms at 10 amp current.
IV.
Resolution & Accuracy: Resolution:0.1 micro Ω in lowest resistance range.
Accuracy Value ± 0.5% ± 2 digits.
V.
OLTC Testing: The kit should be capable of checking the current v/s time
characteristics during the tap change. It should be able to display the magnitude
of current variation during tap change operation in %. The kit should present the
transition time from one tap to the next tap in the test results.
VI.
Temperature Sensor: Kit should have facility to measure the temperature with
RTD sensor. It is to be supplied with kit.
VII.
Open Circuit Voltage: 50 V DC
VIII.
Temperature Correction: The kit should have the facility to have correction of
resistance value to a reference temp. i.e. provide temp. compensated reading of
resistance (for Copper & Aluminum).
IX.
Test Lead / Accessories: One complete set of cable of sufficient length (Min 20
Mtr) with suitable clamps & connectors, compatible with the instruments should
be provided for successfully carrying out the test in substation. Additionally all
the required accessories should be provided for the smooth functioning of kit.
Further hard carrying proper safety of the kit during transportation shall have to
be provided. All the standard accessories for desired monitoring, operation &
control of instrument shall have to be provided.
X.
Design/ Engineering: The complete equipment alongwith complete
accessories must be designed /engineered by Original Equipment Manufacturer
XI.
Power Supply: It shall work on input supply variations, Voltage:230±10%,
Frequency:50Hz ±5% on standard sockets.
XII.
Operating Temperature: 0 to + 50 deg C
XIII.
Relative humidity: Max. 95% non-condensing
XIV.
Protection/ Control: Against short circuit, over load, transient surges etc. The
instrument should have facility of automatically discharging the specimen when
test is completed or when current cable is accidentally disconnected or when
instrument power supply is lost. The kit should have built in rapid discharge
circuit for automatically discharging the stored energy in the transformer at the
end of each test. Kit should also have indication to show the status of
discharging.
Volume-II
87
400KV 500 MVA Transformer
XV.
Weight: It should be portable for easy movement.
XVI.
Software: The software should be suitable for automatic testing & report
generation including OLTC testing. The kit should have facility to conduct the
test through laptop as well in stand-alone mode.
XVII.
Display/Control: Onboard, large back lit graphic LCD Display. Operation
through built-in keypad as well as through external laptop.
XVIII. Printer: In-built thermal printer
XIX.
PC Interface: Kit should have RS232 or USB port for PC interface. Kit shall
include supply of one laptop PC of Dell / Lenovo /HP make with latest
specifications such as Core i3 Intel Processor, 2 GB RAM, 320GB or better HDD,
15” TFT screen, Combo 24XCD R/W Drive i.e. having CD read / write facility
complete with required cables and connectors with preloaded operating system
MS Window 7 Professional or better with latest version application software
required for storage, analysis and record management. The laptop shall be
supplied with suitable antivirus software.
XX.
Memory: Build-in non-volatile memory to store minimum 5000 results.
XXI.
Environment: The test kit shall be compatible for EMI/EMC/Safety environment
requirements.
XXII.
Calibration Certificate: Unit shall be duly calibrated before supply and the date
of calibration shall not be older than two month from the date of supply kit. The
calibration certificate should have traceability to NPL or any NABL accredited
Laboratory.
XXIII. Training: Supplier shall have to ensure that the instrument is made user friendly.
The supplier shall also have to arrange necessary training to engineers after
supply of the instrument.
XXIV. Commissioning: Successful tenderer will have to commission the instrument.
XXV. After Sales & Service: Tenderer will have to submit the documentary evidence
of having established mechanism in India for prompt services.
XXVI. Accessories: Any other item or accessories, which are essentially required for
satisfactory operation of equipment & for meeting requirements of this
specification shall be deemed to be within scope of the Tenderer irrespective of
whether these are specifically indicated here or not.
XXVII. Clamp: Suitable size of 3 Nos. clamps for connection of X-mer bushing are to be
provided with instrument so that lead of instrument connected properly. The
preferred vendor for Winding Resistance measurement kit shall be Tettex/
IBEKO Power AB make.
Volume-II
88
400KV 500 MVA Transformer
38.0 Please ensure the bid document containing number of pages have been
properly page numbered and each page is signed by the Tenderer. All bid
documents including schedules and Annexures should be indexed properly
and Index of the document should be enclosed/placed at the beginning of the
bid document.
Volume-II
89
400KV 500 MVA Transformer
ANNEXURE –I
PRINCIPAL PARAMETERS FOR 500 MVA, 400/220/33 KV
POWER TRANSFORMER
The transformer shall conform to the following specific parameters described
hereunder:No.
1
DESCRIPTION
PARAMETERS
Type of power
transformer/installation
Auto 3 phase Suitable for outdoor
installation
2
Type of Mounting
Mounted on rails Center to center
distance 1676 mm+ Rail width,
longitudinal and transverse both
3
Suitable for system frequency
50 Hz
4
Rated voltage ratio: HV/IV/LV
400/220/33 KV
5
No. of phases
Three
6
No. of windings
Auto transformer with tertiary
7
Type of cooling
ONAN/ONAF/OFAF
8
MVA Rating corresponding to
a) ONAN Cooling (60%)
b) ONAF Cooling (80%)
c) OFAF Cooling (100%)
Method of connection
HV
IV
300
300
400
400
500
500
HV - Star
IV - Star
LV - Delta
10
Connection Symbol (Vector
group)
YnaOd11
11
System earthing
Solidly/effectively earthed
12
Percentage Impedances, Voltage Principle / Highest / Lowest tap
on normal tap and MVA base
corresponding to HV/IV rating
with applicable tolerances:
9
13
a. HV-IV
Anticipated continuous loading
12.5%+10%tol
a) HV and IV
Not to exceed 110% of its rated
Capacity.
Suitable for no load operation as
well as for loading to its rated
capacity with capacitive or inductive
loading or combination of both
(Subject to a maximum of 33% of
the rated capacity of HV winding
b) Tertiary
Volume-II
LV
100
134
167
90
400KV 500 MVA Transformer
No.
14
15
16
17
18
19
20
21
Volume-II
DESCRIPTION
PARAMETERS
Tap Changing gear :i. Type
ii. Provided on
iii) Tap range
iv) Tap step
v) Voltage and current rating
Over voltage operating capability
and Duration
Minimum Air core reactance of
HV
Windings
Flux density
a) Working Flux density in any
part of core and yoke at rated
MVA, frequency and normal
voltage
b) Maximum flux density in any
part of core and yoke at 110%
voltage &(-) 4% frequency
variation shall not exceed
Insulation levels :For windings
a) 1.2/50 micro second wave
shape lightning impulse
voltage withstand (KVp)
b) Power frequency voltage
withstand (KV rms)
c) Switching surge voltage
withstand (KVp)
Type of winding insulation
ON LOAD (bidirectional/linear type)
Provided
on
series
winding
immediately before IV tapping point
for variation of 220KV voltage
-10% to +10%
1.25%
245 KV and 1800/2100 Amps.
110% continuous
125% rated voltage for 60 seconds.
140% rated voltage for 5 seconds
20%
1.65 Tesla
1.90 Tesla
HV /IV /LV:
1300/950/250
PD at 1.5 Um /√3 /395/95
1050/ - / -
a) HV/IV winding
Graded
b) LV winding
System short circuit level and
duration
for which the
transformer shall be
able to
withstand thermal and dynamic
stresses (kA rms/sec)
Noise level when energized at
rated
voltage and frequency but
without load.
Full
63 KA for 3sec. for 400KV
40 KA for 3sec. for 220 KV
31 5 KA for 3sec. for 33 KV
91
As per NEMA standards
(Copy of standard to be
furnished with TENDER)
400KV 500 MVA Transformer
No.
22
23
24
25
26
DESCRIPTION
PARAMETERS
Permissible temperature rise
Over ambient temp of 500C.
i) Of top oil measured by
thermometer
ii) Of winding measured by
resistance
40 deg.C
Minimum clearance in air (mm)
a. HV (400)
b. IV (220)
c. LV ( 33)
Terminals : (Bushings)
a. HV winding line end
b. IV winding line end
c. HV/IV winding Neutral end
d. LV winding
a. Radio Interference voltage
level at 1 MHz. & 266 kV rms
phase to ground voltage for
HV
winding
b. Maximum visual corona
exitinction voltage (KVrms)
c. Partial discharge level at
364KV
Cooling Equipments :
a) Number of banks
b) Number of pumps
Ph-Ph
4000
2700
700
c) Number of Fans
27
Bushings :
a. Voltage Rating (KV rms
b. Current Rating (Amps)
c. Lightning impulse voltage
withstand(KVp)
d. Switching surge voltage
(KVrms)
e. Creepage distance (mm)
f. One min. power freq. Voltage
(KVrms)
Volume-II
92
45 deg.C
Ph-Ground
3500
2400
660
420 KV RIP condenser
245 KV RIP condenser
72.5 KV RIP condenser
72.5 KV RIP condenser
1000 micro volt
320
500 pico columb (maximum)
Two 50% cooler banks
Adequate number of pumps and
one
set of standby pump in each bank.
Adequate number of Fans with
standby Fans for each bank.
HV / IV / LV & NEUTRAL
420 / 245 / 72.5
1250/2000/3150
1425/1050/325
1050/ - / -/
10500/6125/1813
630/460/140
400KV 500 MVA Transformer
No.
28
29
30
DESCRIPTION
PARAMETERS
a) Bushing Current
Transformer for purchaser’s
use
i) Type
Quantity
ii) Current Ratio HV & IV(A/A)
iii) Knee point voltage (V)
iv) Accuracy class
v) Secondary resistance(Ohms)
vi) No. of cores
b) Neutral side C.T. for
Purchaser’s use (for
restricted E/F protection)
i) Type
ii) Quantity
iii) Voltage class
iv) No. of cores
v) Current Ratio (A/A)
vi) Knee point voltage (KVp)
vii) Secondary resistance
(Ohms)
viii) Type of mounting
HV
ix) Turns ratio
Identical to the turns ratio provided
on HV & LV side
x)
In neutral lead before connection to
s/s. earth the detailed arrangement
shall be worked out by the supplier
as per actual layout.
Location for mounting
Single ph. ring type turret mounted
3 nos
3nos
1000-2000/1-1
1000-2000/1-1
1000 V
1000 V
PS
PS
5
5
2
2
Single phase outdoor mounted
One number
72.5KV
Two
1000-2000/1-1
1000V
5
Frame mounted
c) 33 KV class CT for Tertiary
winding.
Single phase turret mounted
i. Type
1600/1
1600/1-1
ii. Current Ratio (A/A)
Three number One Number
iii. Quantity
PS
Core1- 5P10,
iv. Accuracy class
Core2 – class I
As per requirement or < six ohm
v. Secondary Resistance
1000 V
---vi. Knee point voltage (KVp)
Surge capacitors :
40KVrms
IS 11548 / IS 9348
50 Hz
i) Rated voltage
ii) Applicable standards
iii) Rated frequency
Volume-II
IV
93
400KV 500 MVA Transformer
No.
Volume-II
DESCRIPTION
PARAMETERS
iv) Rated capacitance
v) Tolerance on capacitance
value
vi) One minute power frequency
withstand voltage
vii) Lightning impulse withstand
voltage
viii)Temperature rise over
designed ambient
temperature
ix) Temperature coefficient
x) Bushing/support insulator for
surge
capacitor
a) Applicable standard
b) Rated voltage
c) Creepage distance (mm)
d) Power frequency withstand
voltage
e) Lightning impulse withstand
voltage
94
0.125 micro farad.
-5% to +15% of rated value
95 KVrms
250 KVp
Not more than 10 deg.C
0.035%/deg.C
Porcelain housing
IS 5621
40 KV
1820 minimum
95 KVrms
250 KVp
400KV 500 MVA Transformer
ANNEXURE - II
LIST OF FITTINGS AND ACCESSORIES TO BE PROVIDED
WITH EACH POWER TRANSFORMERS.
1.
Each transformer shall be provided with the following accessories.
Volume-II
i
One no. Dial type Thermometers for oil : A dial type
indicating thermometer with repeater of robust pattern mounted
inside FCC at a convenient height to read the temperature in the
hottest part of the oil and fitted with alarm and trip contacts. ROTI
shall also be mounted on RTCC panel. RTD shall be provided with
PT100 temperature sensor having nominal resistance of 100 ohms
at zero degree centigrade.
ii
Winding temperature Indicator : Two nos. WTI for HV (on
extreme phases), one no.WTI for IV ( on middle phase) & one
no.WTI for LV ( tertiary) winding : These shall be indicating type,
with repeater responsible to the combination of top oil temperature
and winding current, calibrated to follow the hottest spot
temperature of the transformer winding. The winding temperature
indicator shall operate a remote alarm before the hottest spot
temperature approaches a dangerous value and
it shall
automatically actuate the cooling fan Motors and oil pumps.
iii
Repeater Winding temperature Indicator (RWTI) : These shall be
as per cl. 11.10 of this section. RTD shall be provided with PT100
temperature sensor having nominal resistance of 100 ohms at zero
degree centigrade. A precision potentiometer mounted inside the
case shall function as a transmitter to operate a repeater for RWTI.
For two windings ( i.e. HV and IV) the transmitter shall be directly
connected to the repeater. For the third winding (i.e. LV) the
transmitter shall be connected to a Resistance Transducer, which
will supply DC for operating repeater.
iv
One magnetic type oil level gauge with low level alarm
contacts and dial showing minimum, maximum and normal oil levels.
v
One plain / prismatic oil level gauge of over lapped type on either
side of the conservator shall also be provided.
vi
Valves (As Per Annexure V) In the Annexure-V of valve schedule,
4 nos. valves are required to be provided in each Thermosyphon
filter. Out of 4 nos., 2 nos. shall be provided for the purpose of
disconnecting the oil flow between the main tank & Thermosyphon
filter and 2 nos. are to be provided for the purpose of filtration of
charge of the Thermosyphon without disconnecting the
Thermosyphon from body .
vii
Minimum 3 nos. pressure relief valves . The quantity of these
valves should commensurate with the quantity of oil in the
transformer and also location of valves should be properly
designed to adequately release the excessive pressure.
95
400KV 500 MVA Transformer
viii
A set of air release valves on the top and on the radiators and also
at appropriate places.
ix
One thermometer pocket for mercury in glass type thermometer.
x
Buchholz relay : One double float gas detector relay with alarm
and tripping contacts to detect accumulation of gas and sudden
changes of oil pressure, complete with shutoff valves and flanges
couplings to permit easy removal without lowering oil level in the
main tank, a blend valve for gas venting, and test valve. Make of
buchholz relay shall be as per our discretion.
xi
Heat exchangers or radiators complete with shut of valves and
with facility for oil draining arrangement.
xii
a. Two oil conservator, with required accessories, one for main
tank and other OLTC. Self re-generating breather for main &
OLTC conservator as per clause no.20.11.1.
b.
Volume-II
Air cell type breathing arrangement with oil preserving
equipment complete in all respects of PRONOL make only.
xiii
Eye bolts and lugs on all parts for easy handling.
xiv
Two grounding earthing terminals at diagonally opposite corner of
tank.
xv
xvi
One rating and diagram plate.
A set of minimum 4/8/12 nos.(as per requirement) flanged bidirectional wheels for rail mounting (for 1676 mm rail gauge.)
xvii
Set of fans, Pumps required for ONAF & OFAF cooling of
transformer with following information
the
a.
Number of Radiator Banks.
b.
No. of cooling fans (Industrial duty of adequate voltage &
rpm) & pumps provided in each bank to ensure 100% ONAF &
OFAF rating of the transformer. As per our specification, for
each bank 20% additional cooling fan & one pump is to be
included which will be duly wired-up.
xviii
Suitable jacking lugs and haulage holes.
xix
Inspection window & main holes with bolted cover
Annexure-IV
xx
Adequate no of Thermosyphon filter assembly (minimum 4 nos)
with suitable supports, valves and pumps for forced but slow
circulation of Transformer oil .
xxi
Lifting arrangement for the complete transformer, core
assembly and also tank.
xxii
One detachable bolted type MS ladder
conservator tank.
96
as
per
coil
each on main tank and
400KV 500 MVA Transformer
xxiii
For the purpose of taking earthing connection from the neutral
bushing, adequate number of brackets with small support insulators
shall be provided on the body of the tank so that earthing could
be arranged by Purchaser near the earthing pit of transformer
itself.
xxiv
A separate weather proof FCC (Fan/Cooler control) cubicle
containing dial type thermometer and winding temperature
indicator and
terminals
of dial type thermometer, winding
temperature indicator, buchholz relay, MOG, control of fans etc.
Please note provision of separate Fan Control Cubicle (FCC) is a
must. FCC shall be suitably dimensioned to accommodate the
following :a
The wiring from Digital RTCC panel shall be brought to
marshalling box and for terminating the same adequate
numbers
of suitably rated terminal connectors shell be
provided.
b
Necessary cable glands shall be included in the scope of supply.
The cable gland and the hole on the gland plate for cable entry
shall be provided.
c
Arrangement for terminating the connecting leads of OTI,
WTI, buchholz, magnetic oil level gauge etc. shall be made in
the marshalling box. It should be possible to read OTI and
WTI readings without opening the box through suitable glass
window. All trip alarm and repeater signals will be transferred
to control room for which arrangement will have to be made.
d Starters for cooling fans & Pumps shall be housed in marshalling
box and necessary switches for local operation of fans and
pumps shall be provided.
e
Local remote control switch for OLTC shall be provided.
f
Space heater with switch, cubicle illumination lamp, fuses,
links overload protection arrangement for motors and other
accessories shall be included in the scope of supply.
xxv
One set of indoor RTCC (Remote tap changer control) cubicle
complete with provision for remote operation of OLTC, as independent
or master/follower scheme, with oil and winding temperature
repeater, tap position indicator with annunciation for fan group
ON/OFF and cooler supply fail indication and Tap changer in
progress including OTI repeater & WTI remote indicator operated by
remote sensors.
xxvi
One set of erection manual/relevant drawing/leaflets should be
secured permanently inside the RTCC cubicle as a guide line for site
erection and commissioning.
Volume-II
97
400KV 500 MVA Transformer
xxvii
Three separate connection i.e. connection from core, connection
from end frame and connection from tank shall be brought out on
to a terminal box with cover. Arrangement for inter connecting these
terminals in the terminal box shall also be provided. This arrangement
shall facilitate verification of core, end frame and tank insulation.
xxviii Mounting of radiators on the 33KV side of 72.5 KV bushing
should be avoided. In no case, the radiators should be
projected above the main tank height.
xxix
All transformers shall be supplied with a full outfit of tools, spanners,
special tools as per Annexure X for assembly and all spanners
shall be double ended and of very good quality of " Gedore " or
"Taparia " or equivalent make.
2.
The equipments and accessories furnished with the transformer shall
be suitably mounted on the transformer for ease of operation, inspection and
maintenance and the mounting details shall be subject to the approval of the
purchaser. All valves shall be provided either with blind companion flanges or
with pipe plugs for protection.
3.
Indication, alarm and relay equipment shall have contacts suitable for
operation with 220V DC supply. Any other accessories or appliances recommended
by the manufacturer for the satisfactory operation of the transformer shall also
have 220V DC as input.
4.
a.
OLTC
and
specification.
its
controls
shall be
as
per
b.
All cabinets & panels shall be
under Clause-16 of specifications.
c.
All 400KV, 220KV & 33KV and neutral bushings shall be of RIP
condenser type and as per Clause 11.13 of specification.
conforming
clause
14
of
to stipulations
5.
NIFPS : Nitrogen injection type fire prevention & extinguishing system with flow
sensitive conservator isolation valve shall be provided for all the transformers as per
clause no. 20.9.
6.
OLMD : On Line Monitoring Device shall be provided for all the transformers
as per clause no. 20.10.
6.1
Essential maintenance spares shall be delivered alongwith each transformer
as per clause 37.0.
6.2 Self regenerating maintenance free dehydrating breathers for transformer as
per clause no.11.7.2.
Volume-II
98
400KV 500 MVA Transformer
1.
Surge Capacitor with structure : 3 nos Surge Capacitor with
structure shall be provided for all the transformers as per cl. No.
20.12.
2.
Provision for Measurement of Degree of Polymerization of
Insulation of Winding of Transformer :- To assess the life of
paper insulation of winding , a provision is to be made inside the
transformer . For this purpose, a container of insulating material of
good electrical, mechanical & chemical properties having free
circulation of oil through it shall be provided at suitable location
where maximum oil temperature is expected. In the container,
atleast 10-12 spools of paper having size not more than one cm be
placed. The container shall be closed and there should not be any
possibility of spools coming out from the container due to natural
circulation as well turbulence of oil during fault etc.
Location of the container shall be selected such that spools may be removed
from the container as and when required by the purchaser during service of
transformer for the purpose of testing of insulating material for “Degree of
Polymerization” (DP test).
8.
COMPATABILITY FOR SCADA OPERATIONS :
The transformer should be compatible for SCADA connectivity. Further, TPI,
ROTI and RWTIs shall suit the following operation through SCADA.
2.
3.
4.
TPI indication on SCADA.
Winding Temperature Indications on SCADA.
Oil Temperature Indication on SCADA.
The necessary fittings required for above SCADA operation are to be
provided in addition to the conventional fittings. Provision of 4-20 mA signal points
of TPI, OTI & WTI meters for SCADA operation having dual outputs are required at
Digital RTCC panel. Further, ratings of the transducers required for SCADA system:i.
ii.
Transformer Tap position Transducers :Input measuring ranges1-1000 ohms per step upto 25 steps.
Dual Output signal of 4 to 20 mA DC.
Supply Input- 90….265V AC/DC
Winding/Oil Temperature Transducers :Dual Output signal of 4 to 20 mA DC.
Supply Input- 90….265V AC/DC
9.
Control cables of adequate length for body protection (viz. Buchholz
relay/PRV etc.) needs to be laid on the tank cover /wall through appropriate
arrangement using cable trays for termination of either ends with proper leveling
during transportation.
Volume-II
99
400KV 500 MVA Transformer
10.
Accessories, which are not included in the above schedule but
details of which are given in Bid specification and which are necessary for
satisfactory operation of Transformer shall be deemed to have been
included in the accepted price without any extra cost to the Purchaser.
Volume-II
100
400KV 500 MVA Transformer
ANNEXURE -III
LIST OF TRANSFORMER ACCESSORIES AND THEIR TEST-CERTIFICATES
TO BE SUBMITTED BY MANUFACTURERS/APPROVED VENDORS
S.
No.
Accessory
Ref. Std.
Test-certificates required
IS2099,IEC60137
1. Appearance, construction and
dimensional check
2. Test
for
leakage
of
internal filling at a pressure
of 1.0 kg/cm2 for 12hours.
3. Insulation resistance IS 2099
measurement
with
2000V
Insulation Tester.
4. Dry/wet
power
frequency
voltage withstand test.
5. Dry/wet
power
frequency
voltage withstand test for test
tap insulation
6. Partial discharge measurement
up to 1.5 UN/_/3 KV.
7. Measurement
of
tangent
delta and capacitance.
1
RIP Bushing
2.
Air Cell
IEC
3.
OLTC
IS 2026 part I,
IEC 60214
Volume-II
101
1.
Dimensional check,
inflation/Deflation at 10
inflation/Deflation at 10 Kpa
2. Pressure test at 10 Kpa for 24
Hr.
1. Oil tightness test for the 8468
diverter switch oil chamber at
an oil pressure of 0.5 kg/cm2
at 100 degree centigrade for 1
hour.
2. Mechanical operation test.
3. Operation
sequence
measurement
4. Insulation
resistance
measurement using 2000V
Insulation Tester
5. Power
frequency
voltage
withstand test on
diverter
switch to earth and between
even and odd contacts.
6. Power
frequency
voltage
400KV 500 MVA Transformer
S.
No.
Accessory
Ref. Std.
Test-certificates required
withstand test on tap selectorbetween stationary contacts,
between max. and min. taps,
between
phases
and
supporting
frames, between
phases.
7. Operation & dielectric test of
complete OLTC
4.
Winding & Oil
Temp Indicator
5.
Pressure Relief
valve
IS13947
1. Functional
test
with
Compressed air to check
bursting pressure, indicating
flag
operation and switch
operation.
2. Dielectric test at 2 KV for one
minute.
3. Switch contact testing at 5A,
240 Volt AC.
4. Leakage test at 75% operating
pressure for 1Hr.
6.
Cooling Fan and
motor assembly
IS 2312
1. Appearance, construction and
dimensional check.
2. Insulation
resistance
measurement
3. Dielectric test at 2 KV
between winding and body for
one minute
4. Operation check.
5. Power consumption, RPM,
Current.
7.
Buchholz Relay
IS:3637
1. Leak test with transformer oil
at a pressure of 3 kg/cm2 for
Volume-II
1. Calibration test
2. Dielectric test at 2 kV for one
minute.
3. Accuracy test for indication
and switch setting scales.
4. Test for adjustability of switch
setting
5. Test for switch rating
6. Measurement of temperature
rise with respect to the heater
coil current.
102
400KV 500 MVA Transformer
S.
No.
Accessory
Ref. Std.
Test-certificates required
2.
3.
4.
5.
6.
7.
8.
9.
8.
Oil Level gauge
including MOG
9.
Pressed Steel
Radiators
10.
OLTC Control
cubical/Cooler
Control cubicle
11.
Bushing Current
Transformers
Volume-II
30
minutes
at ambient
temperature for relay casing.
Insulation
resistance
measurement
with 500V
Insulation Tester.
Dielectric test at 2 kV for 1
minute
Elements test at 1.75 kg/cm2
for
15
minutes
using
transformer oil at
ambient
temperature.
Loss of oil and surge test.
Gas volume test
Mechanical strength test
Velocity calibration test
Appearance construction and
dimensional check.
IS
1. Appearance, construction and
dimensional check
2. Dielectric test at 2 KV for 1
minute
3. Switch contact test at 5A 240V
AC
4. Switch operation for low level
alarm
5. Test for oil levels
IS 513
3. Appearance, construction &
dimensional check.
4. Air pressure test at 2 kg/cm2
under water for 15 minutes
1. Appearance,
construction &
dimensional check.
2. Electric operation
3. Insulation
resistance
measurement using 500 V
meggar at ambient temperature
4. Dielectric test at 2kV for 1
minute
IS: 2705
103
1. Appearance, construction &
dimensional check. Polarity
Check, Measurement
of
insulation resistance.
400KV 500 MVA Transformer
S.
No.
Accessory
Test-certificates required
2. H V power frequency test.
3. Determination of ratio error and
phase angle of measuring and
protection BCTs
4. Interturn insulation test
5. Exciting current characteristic
test,
Secondary
winding
resistance measurement
12.
Terminal
connector
13
Silica Gel
Breather
14
NIFPS
Volume-II
Ref. Std.
IS 5561
TAC/NEPA
norms
104
1.
Dimensional check as per
drawing & visual inspection
2. Tensile test, resistance test
3. Test as per IS 5561
1. Pressure tests
2. Visual & dimension tests
3. Operation test
4. silica gel test
5. Oil compatibility test
1. Lamp test
2. Out of Service
3. Transformer Conservator
Insulator Valve (TCIV) open
4. Transformer Conservator
Insulator Valve (TCIV)
closed
5. Fire Detector trip
6. Buchholz Relay trip
7. Differential Relay trip
8. PRV trip
9. RPRR trip
10. Transformer trip
11. D.C. fail etc..
400KV 500 MVA Transformer
ANNEXURE-IV
SCHEDULE OF INSPECTION COVER/ACCESS WINDOWS
S.No.
Particulars
Size of openings
(Length x Width)
(mm x mm)
Qty.
(Nos.)
1
Inspection cover (man hole)
450x900
1
2
Inspection cover/ Access Window
for OLTC (with lifting handle on
tank wall)
450x900
3
3
Inspection cover/ Access Window
for HV Bushing
500x500
3
4
Inspection cover/ Access Window
for IV Bushing
500x500
3
5
Inspection cover/ Access Window
for LV (Tertiary) Bushing
500x500
3
6
Inspection cover/ Access Window
for Common Neutral Bushing
500x500
1
8
Inspection cover on Tank cover
– 2nos for HV & 1 no for IV .
300x600
3
300x400
1
500mm dia
1
9
10
Note:
Volume-II
Inspection cover on Tank cover
for core-end frame-tank earthing
arrangement
Inspection cover on Conservator
This Schedule shall be finalized at the drawing approval stage.
105
400KV 500 MVA Transformer
ANNEXURE-V
SCHEDULE OF VALVES
Description of Valves
Size
Item
1
2
3
4
5
6
7
Oil inlet / outlet valve for Tank
Top /Bottom Oil filter valve
Top / Bottom oil sampling valve
Drain plug bottom tank
Drain valve (Tank)
Drain valve (Tank)
Valve for outlet from & inlet to tank
250NB
50NB
25NB
50NB
100NB
100NB
250NB
8
Valve for pipe assembly and bank
I&II
Isolating valve for bank I&II
50NB*
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
Quick Oil discharge valve
N2 Injection valve
Valve for oil inlet & outlet for OLMD
Radiator Isolating valve
Drain plug on radiators
Air release plug on radiators
Drain cum filter valve on header
Drain plug on header
Air release plug on header
Drain plug on inlet/outlet pipe
Air release valve on tank cover
Pressure release valve (Main tank)
Thermosyphon filter valve
Air release plug on Thermosyphon
filter
Thermosyphon pump isolating valve
Thermosyphon pump bypass valve
Thermosyphon isolating valve
Oil surge relay isolating valve
OLTC equalizing valve
OLTC suction valve
OLTC Conservator drain valve
Buccholz relay isolating valve
Pre Stressed Non return valve
Gas Sampling valve
Main conservator Drain valve
Main conservator Air release valve
Main Breather isolating valve
Valve for Vacuum breaking during oil
filling
Volume-II
106
250NB
150NB
25NB
25 NB*
100NB
½ ” Bsp
½ ” Bsp
50NB
½ ” Bsp
½ ” Bsp
½ ” Bsp
15NB
150NB
50NB
½ ” Bsp
100NB
100NB
100NB
25NB
25NB
25NB
25NB
80NB
80NB
¼” Bsp
50NB
25NB
25NB
25NB
Qty
Type (Design)
2+2
2+4
1+1
2
1
1
As per
design
As per
design
As per
design
1
6
2
As per
design
Gate valve
Gate valve
Globe valve
4
4*
4*
2*+2*
2
3
8
4
Globe valve
--
4
As per req.
8
3
3
3
1
2+1
1
2
1
1
1
1
Butterfly valve
Gate valve
Butterfly valve
Gate valve
Gate valve
Gate valve
Gate valve
Butterfly valve
Gate valve
Gate valve
Gate valve
Gate valve
Butterfly valve
Globe valve
Gate valve
Globe valve
Globe valve
Gate valve
Gate valve
Gate valve
Gate valve
Gate valve
Gate valve
Gate valve
400KV 500 MVA Transformer
NOTE: 1. All valves shall have position indicators to indicate the status i.e. valves
are in open or shut position.
2. All valves shall be made of gun metal (GM); cast iron valves are not
acceptable.
3. All plugs shall be made of cast iron (CI)/GM
NB- Normal Bore – mm.
* Size & Qty. indicated is subject to change as per design
Volume-II
107
400KV 500 MVA Transformer
ANNEXURE –VI
LIST OF VENDORS FOR MAJOR ITEMS OF TRANSFORMER
“Major items/inputs in transformers’ have to conform to highest quality standards
prevailing.” The vendors of various major items from whom procurement was made by
various suppliers of transformers and quality of which was found acceptable are listed
below. However, major items procured from any vendors meeting the required
specification would be acceptable.
S. No.
1.
2. (a)
Volume-II
Name of Item
CRGO
Winding copper &
conductor
Supplier
M/s Nippon steel corporation, Japan
M/s JFE Steel corp., Japan ( Erstwhile M/s
Kawasaki Corp. Japan)
M/s AK Steel,USA
M/s Armco, USA,
M/s Posco, Korea
M/s Covefi, France
M/s Salzgittar, Germany
M/s Usinor, France
M/s Transfer, France
M/s Mitsubishi, Japan.
M/s AST Terni, Italy
M/s EBG India Pvt Limited, (Indian Agent)
for M/s GELSE NKIRCHEN, Germany
M/s British Steel Corporation , UK
M/s Thyseen Krupp Group of Companies
M/s Invex Filli Isolati Speciali s.p.a. Italy
M/s Sam Dong Korea
M/s Asta, Austria
M/s Smit Draad, Holland
M/s Incab Industries, Jamshedpur
M/s Sterlite Industries, Mumbai
M/s Hindalco Industries
M/s Bhandary Powerlines Private Limited
(BPPL), Manipal.
M/s BCPL Conductors Private Limited,
Manideep, Bhopal.
M/s Bhandary Powerlines Private Limited
(BPPL),Vadodara.
M/s Shakti Insulated Wires, Mumbai
M/s KSH International Pvt Limited, Taloja
M/s Delta-Trans Conductor, Mumbai
M/s Vijay Electricals, Hyderabad
M/s RIMA Transformers & Conductors Pvt.
Limited, Bangalore.
M/s Lacroix and Kress (GMBH) hopal
108
400KV 500 MVA Transformer
S. No.
Name of Item
(b)
CTC Conductor
3.
Precompressed
press Board & press
Board components
4.
Insulating Material
5.
Air Cell
6.
Gaskets
7.
Bushing
Volume-II
Supplier
M/s Pirellicavi Italy
M/s Shree Cable & Conductors, hopal
M/s Chandra Metals, Allahabad
M/s Rational Engineers Limited, Thane (MS)
M/s Apar Industries Limited, Mumbai
M/s Sam Dong Korea
M/s Invex Filli Isolati Speciali s.p.a. Italy
M/s Loc Roix AND KRESS – Germany
M/s Chandra Portico ltd silvassa
M/s KSH International Pvt. Ltd, Chakan.
M/s Shree Cable & Conductors, Bhopal
M/s Rational Engineers Limited, Thane (MS)
M/s Apar Industries Limited, Mumbai
M/s H. Weidmann, Switzerland
M/s ABB fige Holms, Swedan
M/s Senapathy Whiteley, Banglore
M/s Raman Board, Mysore
M/s Dupont, USA
M/s Senapathy Whiteley, Banglore
M/s H. Weidmann, Switzerland
M/s Munksio
M/s Amotfors, Sweden
M/s Krammerer
M/s PRONAL, France
M/s PRONAL, Asia manufacturing SDN
BHD Malaysia/Repute makes subject to
approval
M/s Nucork, Bhiwadi / M/s Unirub, Pune
M/s Talbros, Faridabad
M/s Cortica, Chennai
M/s Packing & Jointing, Chennai
M/s Indian Rubber Products, Haridwar
M/s Bombay Oil Seal Mfg. Mumbai
M/s MGM Rubber Kolkata
M/s Bharat Corrub Industries, Vadodara.
M/s Indian Cork Industries, Bahadarpur
M/s Nu-cork, Gurgaon
M/s BHEL
M/s CGL
M/s TELK
M/s ASEA-MICAFIL
M/s Passonivilla
M/s Yash high voltage (upto145 KV)
109
400KV 500 MVA Transformer
S. No.
Name of Item
Supplier
M/s GE T&D India Bangalore
8.
Terminal Connector
M/s Best & Crompton, Chennai
M/s PeeVee Engg., Bangalore
M/s Milind Engg., Mumbai
M/s Nootan, Baroda
M/s Utsav, Baroda
M/s Vinayak and Co., Mumbai
M/s Megha Engg. Enterprises, Chennai
M/s Klemmen Engg. Corporation , Chennai
9.
OTI/WTI with
repeater
10.
Magnetic oil gauge
11.
Buchholz Relay & Oil
surge relays
12.
Pressure Relief
Device
13.
Fan & Motor
14.
Un-impregnated
Densified laminated
wood
M/s Accurate Control, UK
M/s AKM, Swedan
M/s Perfect Control, Chennai, India
M/s Preci Measure, Banglore
M/s Radix Electrosystems Pvt. Ltd/ Radix
Pyrotech India
M/s Sukrut Udyog, Pune
M/s Yogya, Jhansi
M/s Fukuda Instrument, Japan
M/s Atvus,Calcutta
M/s English Electric, Chennai
M/s Prayog (AJ Services); M/s BHEL
M/s Instrument and Control, Vadodara
M/s Qualtrol, USA
M/s GE, USA;
M/s Sukrut Udyog, Pune
M/s Viat Instruments Pvt Ltd, Kolkatta
(Erstwhile M/s Atvus Industries, Kolkatta)
M/s Viat Sanad Ahmedabad
M/s Marathon Electric Motors (India) Ltd,
Kolkata (Erstwhile M/s Areva, (Alstom),
Kolkata)
M/s CGL, Mumbai
M/s Khaitan, Kolkata.
M/s EPC, Kolkata
M/s Permali Wallace Bhopal
M/s Kit ply Assam
M/s Mysore Polymers Banglore
M/s Narmada Forest Ind. Pvt. Ltd. Bhopal.
M/s Western India Plywood , Kerala
M/s Dehonite, Germany
M/s Surendra Composites, Bhopal
M/s Rochling Engineering plastics,
Germany
Volume-II
110
400KV 500 MVA Transformer
S. No.
Name of Item
Supplier
M/s Leader
M/s Bombay Metal & Alloys
M/s Audco
M/s Petson
M/s Manixon
M/s Creseant
M/s Precision Engg. Kottayam,
M/s Eapen Joseph, Kottayam
M/s Apex Piping Systems, Jalandhar
M/s Liberty Engg., Mumbai
M/s Niton Valves, Mumbai
M/s Eapen Joseph & co., Coimbatore
M/s GG Valves ,Udaipur
Ms Siemans
M/s MDS
M/s S&S
M/s Havell’s
15.
Valves
16.
MCB
17.
Fuse
M/s Siemens/ S&S / Areva / Havell’s
18.
Tank Steel
M/s SAIL
M/s Essar
19.
OLTC Complete
20.
Terminal Blocks
21.
Silica gel Breather
22.
Transformer oil
23.
Radiator
M/s BHEL
M/s TELK
M/s Easun, Madras
M/s CTR, Pune
M/S ELMEX
M/S Technoplast,
M/S Tosha
M/S Yogya Enterprises, Jhansi.
M/S Anusen Industries, Pune.
M/s Instruments & Controls , Vadodara,
India
M/s Apar Limited, Mumbai
M/s Savita Chemicals Ltd, New Mumbai
M/s CTR Manufacturing Industries, Pune
M/s Thermal Transformer Product,
Bangalore
M/s Exotherm, Bangalore.
M/s P.E. Engg. Hyderabad.
M/s Hitech Radiators Pvt, Ltd, Mumbai
M/s BHEL, Bhopal
M/s Gururaj Radiator, Naini
M/s Toshiba Transmission & distribution,
Hyderabad
Volume-II
111
400KV 500 MVA Transformer
S. No.
Name of Item
Supplier
24.
On Line Monitoring
Device
M/s Kelman, UK
M/s MTE, New Dehli (with extended
warranty)
M/s A-eberle, Germany
25.
Oil flow indicator
M/s Sukrut Udyog, Pune
M/s Viat Sanad Ahmedabad
26.
NIFPS
M/s CTR, Pune
M/s Vendere Aurangabad
27.
Self-re-generating
maintenance
breather
M/s MESSKO MR, Germany
28.
RIP bushings
(PGCIL approved)
(Subject to approval
of MPPTCL)
M/s ABB AB, Sweden
M/s Massa LLC Russia
M/s MGC Moser-Glazer AG Switzerland
M/s HSP, Germany
M/s ABB Switerland Ltd, MICAFIL
M/s GE Grid Solutions, Italy
M/s Yash Highvoltage Ltd, Vodadara (with
extended warranty)
Volume-II
112
400KV 500 MVA Transformer
ANNEXURE – VII
DRAWINGS AND DATA TO BE FURNISHED BY THE TENDERER.
The following drawings and data for each items are to be submitted on
placement of order.
(a)
Outline dimensional drawings of transformer and
its accessories
including conservator complete with Bill of material and details of all
parts, their quantity, rating & name of Vendors indicating clearances of
transformer body from live terminals i.e. HV,IV,LV.
(b)
Drawing of transformer tank with location of inspection windows, thickness
of side/bottom/top of tank, details of stiffener.
(c)
Drawing indicating limbed core construction with complete details of no.,
width and wt. of core laminations with size of steps; thickness of core
laminations ; dimension of window; size of limbs; Gross and net core ; wt. of
complete core.
(d)
Drawing indicating core belting arrangement with details of belting, belting
material etc.
(e)
Large scale dimensioned drawings for HV,IV & LV windings of the
transformer; size and no. of parallel of HV,IV, LV and of, cooling ducts,
coil clamping arrangement, no./size & location of pressure screws, clamping
ring; top yoke arrangement etc. The details should commensurate with the
short circuit calculations submitted by you for each rating of transformer
(f)
Detailed drawing of transformer tank with complete core and winding
indicating clearances inside transformer tank as also passage and space
for free movement of at least two persons for inspection of active parts etc .
(g)
Schematic diagram showing the flow of oil in the cooling system as well as
each limb and winding. Longitudinal and cross-sectional views showing the
duct sizes, cooling pipes etc. for the transformers/radiators drawn to scale .
(h)
Drawings giving the weights for foundations.
(i)
Combined Rating and diagram plate including tap changing, which should
also include details of guaranteed and measured no load and load losses as
also winding resistances and percentage impedances at all taps.
(j)
Schematic control and wiring diagram for all auxiliary equipment and
control cubicle.
(k)
Drawing showing constructional details, dimensions, mechanical &
technical particulars of bushings. Arrangement of terminals and details of
connection of bushing shall also be indicated in drawing with their technical
particulars.
(l)
Transportation drawing of transformer.
(m)
Details of fittings and cable box.
Volume-II
113
400KV 500 MVA Transformer
(n)
Drawing showing arrangement and details of tap changing gear including
selector switch, diverter switch and drive mechanism.
(o)
Valve Schedule plate.
(p)
Oil filling instruction plate for conservator fitted with Air cell breather
arrangement including equalizing arrangement if any required at the time
of taking full Vacuum at site.
(q)
Drawing and instruction for fitting of Air Cell.
(r)
Drawing of conservator indicating internal details of air cell MOG, oil level
gauge and silica gel breather pipe fitting arrangement.
(s)
Drawings of all HV, IV & LV bushings with complete details meeting TS
requirement.
(t)
Drawings of HV,IV,LV & neutral terminal connectors
thickness, no. of nut bolts with size and other details.
(u)
Drawing of detachable bolted type MS ladder with its complete details and
fitting arrangement on transformer/ conservator tank.
(v)
Drawing for HV/IV neutral earthing arrangement indicating voltage rating of
insulators and its fitting arrangements, size of copper strips, terminal
connectors etc.
(w)
Detailed drawing
transformer tank.
(x)
Drawing
tank.
(y)
Detailed internal drawing of transformer indicating transportation locking
arrangement provided to avoid shifting of core assembly.
(z)
Drawing showing weights of transformers, cooling fan structures, FCC
structures with distance from central line of transformer for casting of civil
foundation for transformer and associated equipments.
(aa)
Drawing of Earthing terminal box showing earthing arrangement for core, end
frame, tank giving details of voltage class and current rating of terminal
bushings.
(ab)
Drawing indicating insulation thickness details and other arrangement
provided between core assembly and bottom yoke and base of bottom of
tank.
(ac)
Drawing indicating details of ‘O’ ring
transformer tank covers.
(ad)
Drawing of stiffeners provided on top, each faces/sides of tank with their
number and size.
(ae)
Drawing indicating number, location, size of shields/ magnetic shunts and its
material provided inside the tank as per clause 11.1 (g).
Volume-II
indicating plate
indicating two views of all valves provided in the
of Thermosyphon filter with fixing arrangement with transformer
114
gasketting arrangement provided in
400KV 500 MVA Transformer
(af)
Drawing indicating internal details of transformer giving complete details of
clearances from live parts.
(ag)
Drawing of internal LV winding termination arrangement indicating minimum
clearance between core and LV take off lead.
(ah)
Drawing of Neutral Current Transformer with details of its mounting
arrangement.
(ai)
Drawing of On Line Monitoring Device with details of mounting arrangement.
(aj)
Drawing of Neutral Current Transformer with details of its mounting
arrangement.
(ak)
Drawing for Lead termination to bottom of HV , IV & LV RIP bushings.
(al)
Internal drawing & design of Core & Winding indicating all attachment with
identification numbers, description including take-off arrangement of lead
connection for Core & End frame and related Bill of Material
(am)
Locking arrangement drawing for tank top cover, core & winding with
complete dimension & details.
(an)
Plan view of the bottom of Bell Tank for complete details of core coil resting
arrangement, indicating clearly dimensional details, material of insulation,
clamping arrangement with details of nuts/ bolts, clearance from all sides
provided at bottom.
(ao)
Drawing indicating complete details, dimension & mounting arrangement of
OLTC inside the tank with respect to End frame.
(ap)
Drawing indicating complete details, dimensions & fixing arrangement of
static end rings if used.
Other relevant drawings.
As soon as possible after the award of the contract the manufacturer shall
supply four (4) copies of the drawings as listed out above, which will describe the
equipment in details for approval and shall subsequently provide ten complete
sets of final drawings, one of which shall be auto-positive suitable for taking blue
prints. Ten sets of instruction books, operation and maintenance manuals and
spare part bulletin, shall be supplied. In addition to above two sets of manuals and
drawings with test certificates for each unit to be despatched as per despatch
instructions.
Volume-II
115
400KV 500 MVA Transformer
ANNEXURE VIII
DESIGN CALCULATIONS & DESIGN DATA REQUIRED TO BE SUBMITTED
FOR POWER TRANSFORMER
It should be specifically noted by the Tenderers that submission of following
Design Calculations & Design Data is necessary on placement of order for our
approval.
(1) SHORT CIRCUIT WITHSTAND CAPABILITIES : The calculations to prove
dynamic and thermal short circuit withstand capability of transformer shall be
submitted for the fault level indicated as under:
400KV
220KV
33KV
-
63 KA for 3 secs.
40 KA for 3 secs.
31.5KA for 3 secs.
The design of winding assembly, which is to be furnished in the drawing as per
Sr. No. (e) of Annexure VII should be commensurating with these calculations. The
details of clamping ring shall be indicated in the drawing .
(2) DESIGN DATA OF CORE & WINDING : On the basis of offered flux density
and current density, the TENDERERs shall furnish following design calculations &
data. Calculations regarding wt. of core & copper and also calculations for losses
will be brought out to justify the offered transformer losses. :
(A) Core Data: Details of core material i.e Name of Manufacturer, Manufacturer’s
type designation for core , thickness of core, curve for Loss Vs Flux density, No
of steps of Core & No of limbs, gross core area , stacking factor , Net core
area ,height & width of core window, center to center distance of limb, voltage
per turn, wt. of core material, working flux density , core loss in watts per kg
marked on graph for grade of core material & selected flux density, building
factor
and calculated no load loss in watts, guaranteed no load loss. A
drawing indicating details of core i.e. limbed construction, step width &
thickness , core belting, top & bottom yoke plate etc shall be submitted.
(B) Winding Data: wt. of copper for windings ie. for HV(series), IV(common) ,tap,
LV(tertiary), cross sectional area , current density, type of coil, ID/OD/mean dia
of coils, size of winding conductor including parallels, no. of turns per phase,
no of spacers, length of mean turn, weight of copper without paper covering,
resistance per phase of winding at 75 deg C, I2R loss at 75 deg C & normal
tap, eddy current & stray loss at 75 deg C , total copper loss at 75 deg C ,
guaranteed transformer losses at 75 deg C.
Complete details of Insulation components i.e. Top & Bottom clamping rings,
washers, Pressboard blocks & cylinders, Pressboard spacers & Phase
barriers, Pressboard segments etc shall be submitted indicating qty , thickness
in mm, width & height , wt.
Volume-II
116
400KV 500 MVA Transformer
Dimensioned drawings indicating details of winding , ducts, insulation , take off
arrangement, clamping ring , pressure points etc shall be submitted.
(3) DESIGN OF TANK : Complete mechanical design of transformer tank including
details of stiffeners shall be submitted . The tank shall be designed to withstand the
following without permanent distortion.
(i) Mechanical shocks during transportation.
(ii) Vacuum filling of oil at 10 milli torr in transformer with all fittings.
(iii) Continuous internal pressure of 35 kN/m2 over normal hydrostatic
pressure of oil.
(iv)
Short circuit forces &
(v) Under seismic condition /events both horizontal/vertical .
The calculations for tank stiffeners shall be submitted to prove no. & size of
stiffeners are adequate to withstand full vacuum & pressure . Drawing of tank shall
be submitted indicating stiffners .
(4) DESIGN OF STATIC END RINGS (SER) AND MAGNETIC SHUNTS : Details
of Static End Rings (SER) and magnetic shunts , if provided , with calculations shall
be submitted . A drawing indicating locations , size ,material of SER and magnetic
shunts shall be submitted.
(5) QUANTITY OF OIL : Complete calculations of oil quantity to be utilized in
transformer for first filling shall be submitted . The calculations shall indicate
(i) Volume of tank including turrets, conservator main & OLTC ,volume of
headers & Radiators, oil quantity in OLTC & thermosyphon filter.
(ii) Oil displacement by Active parts i.e. core - coil assembly,
(6) CAPACITY OF CONSERVATOR & SIZE OF AIR CELL : While furnishing
details of conservator & air cell type sealing arrangement, the TENDERER shall
submit details & calculations for adequacy of size and capacity of Pronal make air
cell for the rating of the power transformer and also for the quantity of oil required.
Catalogue of Pronal should be enclosed clearly marking type designation of selected
size of Air cell. A drawing indicating complete details of conservator with Air cell shall
be submitted .
(7)
CAPACITY OF PRESSURE RELIEF DEVICE: Tenderers must submit
calculation to prove that the capacity/rating of pressure relief device and locations of
the same for the transformer will adequately meet our requirement. Constructional
and design details of pressure relief device must be furnished and it should be
proved by calculation that the size and setting of pressure relief device is
adequate considering the rating of the transformer and quantity of oil in the
transformer. A drawing indicating complete details of PRDs & their locations on tank
shall be submitted .
Volume-II
117
400KV 500 MVA Transformer
(8) CALCULATIONS FOR TEMPERATURE RISE & HOT SPOT WINDING
TEMPERATURE : The limits of temperature rise for windings, oil and hot spot have
been specified . Temperature rise calculations at rated full load, 110% load and
125% load considering 100% cooler banks, 50% cooler banks and without coolers
shall be furnished as indicated below :
(a) 100 % Loading : (i) 20 minutes duration
- 100 % cooler bank
- 50 % cooler bank
- without cooler bank
(ii) 10 minutes duration - 100 % cooler bank
- 50 % cooler bank
- without cooler bank
(b) 110 % Loading : (i) 20 minutes duration - 100 % cooler bank
- 50 % cooler bank
- without cooler bank
(ii) 10 minutes duration - 100 % cooler bank
- 50 % cooler bank
- without cooler bank
(c) 125 % Loading : (i) 20 minutes duration - 100 % cooler bank
- 50 % cooler bank
- without cooler bank
(ii) 10 minutes duration - 100 % cooler bank
- 50 % cooler bank
- without cooler bank
The calculations shall indicate temperature gradient (for all windings i.e.
HV,IV,LV,tap), load losses at lowest tap for all windings , Eddy current & stray
losses, thermal Constant Value & calculations with parameters affecting the values
for above conditions for top oil temperature & winding hot spot temperature .The
Calculations for Hot Spot winding Temperature and calculations for Temperature
Rise shall be submitted .
(9) COOLING CALCULATIONS : Calculations of tank surface for heat dissipation,
details of radiators , fans for ONAN, ONAF & OFAF cooling shall be provided .
(10) OVERFLUXING CAPABILITY: A curve to prove suitability of transformer to
withstand various overfluxing conditions for the duration indicated in clause 4.4.1 to
4.4.3 without core saturation shall be furnished .
(11)
CAPACITY OF FILTER & BREATHER :
(A)
Number and Capacity of each Thermosyphon Filter : The TENDERER
shall submit details & calculations for adequacy of size and capacity of
thermosyphon filter for the oil quantity in the power transformer . While
furnishing details of thermosyphon filter arrangements, the TENDERER must
confirm clearly the number of thermosyphon filter, its size and capacity is
adequate for the rating of power transformer. The TENDERER shall submit
Volume-II
118
400KV 500 MVA Transformer
details & calculation to prove for adequacy of size and capacity of
thermosyphon filter.
(B)
Capacity of Breather : The TENDERER shall submit details & calculations
for adequacy of size and capacity of silica gel breather for the oil quantity
in the power transformer.
(12) RATING OF ON LOAD TAP CHANGER (OLTC) : To verify the adequacy
and suitability of the OLTC components, it is necessary to furnish the calculations
for selecting the proper rating of transition resistance as well as the normal current
rating of OLTC. The calculations shall include the temperature rise of the OLTC
diverter switch and also the short circuit current considered for calculation of
temperature rise.
Calculations shall be submitted to prove that the current rating of OLTC is
adequate for the rating of the transformer winding taking in to account the over
loading capability as per IS 6600. The basis for selection of transition resistance and
its current carrying capacity shall also be submitted. In this regard the circulating
current in tap winding during tap change operation through transition resistance shall
be taken in to consideration. Adequacy of insulation provided in the OLTC between
various parts needs to be established with specific reference to the voltage between
two taps. Confirmation shall be given that the OLTC is suitable for TENDERirectional
flow of current. The through current capacity shall be adequate to handle on
continuous basis the winding current including over loading as per IS 6600. The
through current rating and the rating of transition resistance shall take in to account
the short time current rating of the winding. Capability to handle short circuit current
to be established by calculations and also by test reports.
(13) Capacity of Nitrogen Cylinder, pressure in Nitrogen Cylinder to be used during
transportation shall be submitted.
(14) Size & capacity of Oil sump/ pit for Nitrogen Injection Fire Protection System
shall be submitted.
(15) DESIGN REVIEW : The “Design Review” of the 500 MVA, 400 KV
transformer shall be carried out in accordance with the “Guidelines for
consulting Design Reviews for transformers 100 MVA & above” of Cigre
working group 12.22 (SC12 WG 12.22). The Tenderer shall carry out optimization
of Dielectric design of insulation including electromagnetic design, overload & short
circuit withstand capabilities. During design , transformer modeling shall be done &
finite element software (FEM) may be used.
Note : Tenderers may please note that submission of above calculations &
design data as mentioned in this Annexure is an essential requirement on
placement of order.
Volume-II
119
400KV 500 MVA Transformer
ANNEXURE IX
DETAILS OF INSPECTION PROGRAMME
1.
INSPECTION PROGRAMME :
1.1
Manufacturer shall chalk out a
detailed inspection
and testing
programme for various manufacturing activities for the different components,
fittings & accessories. The MPPTCL also reserves the right to carry out any tests by
a third party at its sole discretion. All Costs of inspection/ tests shall be borne by
Manufacturer.
2.2
STAGE INSPECTIONS :
2.2.1 Manufacturer shall indicate the inspections and checks carried out at various
stages of the manufacture of the transformer. A complete record of stage
inspection shall be kept by Manufacturer and this record shall be made available
for inspection by the representative of the MPPTCL. Manufacturer shall indicate the
manufacturing programme and the MPPTCL will have a right to depute its inspecting
officers during the manufacture. The inspecting stages shall be Fabrication of Tank
& Conservator, core building, coil winding , assembly of coil on core, the condition
of the coil and core after the treatment in vacuum chamber, assembly within the
transformer tank together with application of tap changer etc .
2.2.2 It may be noted that stage inspections for all the units shall be done by us
at the following stages as per the different formats enclosed :
(i) STAGE I : Stage Inspection of Transformer Tank and Conservator after
fabrication.
After fabrication, tank & conservator shall be inspected for
measurement of its dimensions, thickness of sheets used and leakage test by
applying requisite pressure.
In this stage following shall be measured ,recorded & checked in Format I (A,B,C) .
(A) Format I (A) : Inspection of Tank & Conservator
a) Certification of chemical composition and mechanical properties of
plates.
b) Welder's and weld procedure qualification.
c) Testing of electrodes for quality of base materials as per ASME.
d) Dimensional check and visual Inspection of weld .
e) Crack detection, of major strength weld seams by dye penetration test.
f) Measurement of film thickness of inside and outside of X'mer tank and
conservator
i) Oil insoluble varnish
ii) Zinc chromate paint
iii) Light grey paint
Volume-II
120
400KV 500 MVA Transformer
g) Check for physical properties of materials for lifting lugs, jacking pads,
etc. All load bearing welds including lifting lug and jacking parts shall be
subjected to DP test.
h) Leakage test of conservator and tank.
i) Pressure and vacuum test of tank.
j) Surface cleaning by sand or shot blasting.
k) Water logging check on top cover of tank.
l) Certification of all test results.
(B) Format I (B) : Inspection of Valves as per Schedule of Valves
(C) Format I (C) : Inspection of Tank for Inspection Windows.
(ii)
STAGE II : Stage Inspection of Transformer Core during Core Building :
After the core is built but before its clamping, MPPTCL representative
shall inspect the core to take complete weight of the core and also to
measure approximate core loss. If necessary, a small strip of core shall
also be taken for testing at CPRI, Bangalore at our discretion or at any other
testing lab. of repute for measurement of specific loss .
During this stage, following documents shall be verified by our inspector
as a proof towards use of prime core material material for manufacturer of
transformer ordered by us .
i)
ii)
iii)
iv)
v)
Invoice of the supplier
Mills test certificate
Packing list
Bill of lading
Bill of entry certificate by custom's.
The core material shall be directly procured either from the manufacturer or
through their accredited reputed marketing organisation but not through
any agent. A copy of all above documents shall be sent with joint
inspection report for MPPTCL records.
In this stage, following shall be measured, recorded & checked in Format II
(A,B,C).
(A)
Format II (A) : Report in respect of Raw material viz core, copper,
insulating material ,tank steel etc.: Details of various raw material shall be
recorded viz. Name of Supplier/Sub supplier, Test Certificate, QAP Report ,
Invoices, Bill of Lading ,bill of entry etc.
(B) Format II (B) : Report in respect of Accessories: Details of accessories Viz
Buchholz relay, Pressure Relief device, Axles and wheels, Winding and oil
temperature indicators , Cooling fan and radiator, Condenser Bushing &
Bushing Current Transformer, OLTC, Oil level gauge ,OLTC Cubicle and fan
control cubicle, RTCC , Valves, Clamps, Air Cell Breather, Pronol Bag etc.
Volume-II
121
400KV 500 MVA Transformer
shall be recorded i.e. Make, Rating, Factory Test Certificate, QAP Report ,
Invoices etc.
(C) Format II (C) : Inspection of Core .
a)
b)
c)
d)
e)
f)
g)
h)
i)
j)
Checking of in house or vendor core cutting facilities. Sample testing of
core steel for checking specific total loss, ductility
and
bend
properties, resistivity, ageing, magnetization
characteristics
and
thickness.
Check on the
quality of surface insulation & surface finish;
Measurement of thickness and hardness of varnish on stampings;
Solvent resistance test to check that varnish does not react in hot oil;
Check over quality of varnish on stamping, to ensure uniform shining
colour, no hot spots, no over burnt varnish layer and no bubbles on
varnished surface.
Check on the amount of burrs i.e. cutting & edge; Bow Check on
stampings.
During core building dimension, leaning or waviness of core,
tightening torque, dia of resiglass tap to be checked.
Check for the overlapping stampings. Corners of the sheets are to be
apart.
Visual and dimensional check during assembly stage.
Check for inter laminar insulation between core sections after
pressing.
Visual and dimensional check for straightness and roundness of core.
High voltage test on fully built core 2 kV for one minute between
core & yoke bolts, core & core clamps, core clamps & yoke bolts, core
loss measurement.
Certification of all test results.
(iii)
STAGE III : Stage Inspection of Winding after their preparation : Once
the coils are prepared but before the same are fitted on to the core, stage
inspection shall be done to take various measurements and also for weighment
of total weight of coil of each voltage class. Measurement of winding resistance
shall be also done. A small piece of conductor for each type of winding shall be
made available by the manufacturer to our representative.
During this stage, following documents shall be verified by MPPTCL
inspector as a proof towards use of prime copper and insulating material for
manufacturer of transformer ordered by us :
i)
ii)
iii)
iv)
v)
Volume-II
Invoice of the supplier
Mills test certificate
Packing list
Bill of lading
Bill of entry certificate by custom's.
122
400KV 500 MVA Transformer
The winding and insulating material shall be directly procured either from
the manufacturer or through their accredited reputed marketing organisation but
not through any agent. A copy of all above documents shall be sent with joint
inspection report for our records.
In this stage, following shall be measured, recorded & checked in Format III.
(A)
Winding:
a) Sample check on winding conductor for mechanical properties and
electrical conductivity.
b) Visual dimensional checks on conductor for scratches, dent
marks etc.
c) Sample check on insulating paper for PH value, electric strength.
d) Check for the reaction of hot oil on insulating paper.
e) Check for the bonding of the insulating paper on conductor.
f) Check and ensure that physical condition of all materials taken for
winding is satisfactory and free of dust.
g) Check for absence of short circuit between parallel strands.
h) Check for brazed joints wherever applicable.
i)
Measurement of voltage to be carried out when core/yoke is
completely restacked and all connections ready.
j) Conductor-enamel test for checking of cracks, leakage and pin holes.
k) Conductor-flexibility test.
l) Heat shrink test for enameled wire.
m) Measurement of no. of turns, cross sectional area of each winding ,
winding resistance and weighment of windings.
n) Certification of all test results.
(B)
Insulating Material:
a)
b)
c)
d)
e)
f)
g)
(iv)
Sample check for physical & chemical properties of material.
Check for dielectric strength.
Visual and dimensional checks.
Check for the reaction of hot oil on insulating materials.
Dimensional stability test at high temperature for insulating material.
Tracking resistance test on insulating material.
Certification of all test results.
STAGE IV : Stage Inspection of Core Coil Assembly Before Vapour
Phase Drying/Dryout: In this stage , following shall be measured, recorded
& checked in Format IV.
i.
ii.
iii.
iv.
Volume-II
Check Clamping Ring with approved drawing. Check Core Belting,
Check condition of insulation on the conductor & between the
windings.
Insulation test of core earthing .
Check for proper cleanliness and absence of dust etc.
Certification of all test results.
123
400KV 500 MVA Transformer
(v)
STAGE V: Stage Inspection of Core – Coil Assembly After Vapour Phase
Drying/Dryout : In this stage , following shall be measured, recorded &
checked in Format V.
a) Measurement and recording of temperature and drying time during
vacuum treatment.
b) Check for completeness of drying by measuring IR values.
c) Check insulation distance between high voltage & low voltage
connections with respect to earth and other parts.
d) Measure minimum clearance from all sides.
e) Certification of all test results.
Pre-shipment Checks at Manufacturer's Works:
a) Check for interchangeability of components of similar Transformers for
mounting dimensions.
b) Check for proper packing and preservation of accessories like
radiators, bushings, explosion vent, dehydrating breather, rollers,
buchholz relay, control cubicle, connecting pipes, conservator etc.
c)
Check for proper provision of bracings to arrest the movement of core
and winding assembly inside the tank.
d) Gas tightness test to conform tightness.
e) Derivation of leakage rate and ensure adequate reserve gas
capacity.
Installation & pre-commissioning test of Nitrogen Injection Fire Protection
System : After installation the system pre-commissioning tests shall be carried
out jointly before the system is put in service.
2.2.3 Details of Procurement : Manufacturer shall provide us complete details of
procurement of raw materials i.e. core, insulation and copper . Manufacturer shall
also record a certificate .
2.2.4 The MPPTCL also reserves the right to carry out stage inspections
at other stages also, for which advance intimation shall be given and all
necessary cooperation shall be rendered by the manufacturer.
Volume-II
124
400KV 500 MVA Transformer
ANNEXURE X
LIST OF HAND TOOLS FOR SUPPLY
ALONG WITH TRANSFORMER
(A)
One tool box consisting of the following 41 Hand tools of GEDORE
make or equivalent with better quality shall be supplied
1.
Spanners of different sizes
a) Open Jaw Double Ended
-
8 Nos.
b) Cranked ring double ended
-
3 Nos.
c) Tubular Box Double Ended
-
1 No.
2.
Tommy Bar
(For Tabular Box Spanner)
-
1 No.
3.
Adjustable Wrenches
-
2 Nos.
4.
Pipe Wrench
-
1 No.
5.
Screw Drivers Of Different Sizes
-
5 Nos.
6.
Flat Nose, Round Nose, Side Cutting
Pliers
-
3 Nos.
7.
Gasket Punches
-
10 Nos.
8.
Files With Handles
-
2 Nos.
9.
Hammers With Handles
-
2 Nos.
10. Knife With Handles
-
1 No.
11. Adjustable Hacksaw
-
1 No.
12. Cold Chisel
-
1 No.
Total
Volume-II
41 Nos.
125
400KV 500 MVA Transformer
ANNEXURE – XI
UNDERTAKING FOR SUPPLY OF SPARES
FOR 400KV 500 MVA TRANSFORMER
It is confirmed that spares required for satisfactory operation of offered power
transformer shall be made available at reasonable cost for a minimum period of 10
years from the ate of commissioning of power transformer at EHV substation within
MP.
Signature of authorized
Signatory of Tenderer
alongwith seal.
Volume-II
126
400KV 500 MVA Transformer
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
24.
25.
26.
27.
28.
29.
30.
31.
37.
38.
39.
40.
41.
42.
43.
44.
45.
46.
47.
OLTC
OIP
DL type
COPS
RTCC
Cl
IEEMA
KV
KW
IV
LV
VPD
ONAN
ONAF
OFAF
CBIP
OTI
WTI
KA
TC
V
f
VN
FN
CT
PT
Xmer
PRD
PRV
MOLG
OSR
Isc
V
Zt
Zs
θ1
θ0
J
t
Iph
Zpu
Rdc
48.
49.
Hw
N
List of Abbreviation used in technical specification
On load tap changer
Oil impregnated paper
Draw lead type
Conservator oil preservation system
Remote tap changer cubicle
Clause
Indian Electrical & Electronics Manufacturing Association
Kilo voltage
Kilo Watt
Intermediate voltage
Low voltage
Vapour phase drying
Oil natural air natural
Oil natural air forced
Oil forced air forced
Central Board of Irrigation and Power
Oil temperature indicator
Winding temperature indicator
Kilo Ampere
Terminal connector or test certificates as applicable
Voltage
Frequency
Normal voltage
Normal frequency
Current Transformer
Potential Transformer
Transformer.
Pressure Relief Device
Pressure Relief valve
Magnetic Oil Level Gauge
Oil Surge Relay
RMS value of symmetrical short ckt current,KA
rated voltage of system, KV
short ckt impedance of transformer, Ohms
short ckt impedance of system, Ohms
final temperature in degree centigrade
Initial temperature in degree centigrade
short ckt current density amp/mm sq.
duration of short ckt in secs
rated phase current in amps
per unit impedance
DC resistance of the per phase of winding at 75 degree
centigrade
height of winding in cm
no of turns per phase of winding
50.
51.
52.
53.
54.
55.
56.
57.
58.
Dmi
Bi
E
Sn
Pu
Fa
Ai
Ao
m
-
59.
60.
61.
62.
63.
64.
65.
66.
67.
68.
69.
70.
71.
72.
73.
bo
Dmo
Ao
F
D
b
t
n
mA
kg
kl
temp.
max.
min.
vol.
-
mean diameter of inside winding, cm
thickness of inside winding conductor, cm
modulus of elasticity of conductor, cm
rated KVA
per unit impedance
axial imbalance force, Kg
(no of spacers x length x width) for inner winding
(no of spacers x length x width) for outer winding
no of conductors in the radial direction= no of turns x no of
parallel conductor
thickness of outer winding conductor, cm
mean diameter of outer winding, cm
supported area of outer radial spacers
total axial force in MT
mean diameter of clamping ring, cm
width of clamping ring ,cm
thickness of clamping ring ,cm
no of jacking or clamping points
milli ampere
kilogram
kilolitre
temperature
maximum
minimum
volume
MP POWER TRANSMISSION COMPANY
LIMITED
TENDER SPECIFICATION NO. TR-30/2022
FOR
PROCUREMENT OF 400/220/33KV 500 MVA POWER
TRANSFORMERS WITH OIL AND ERECTION, TESTING &
COMMISSIONING OF TRANSFORMERS
(VOLUME-II)
ANNEXURES
ANNEXURE - I TO ANNEXURE - XI
(PAGES 90 TO 126)
MP POWER TRANSMISSION COMPANY
LIMITED
TENDER SPECIFICATION NO. TR-30/2022
FOR
PROCUREMENT OF 400/220/33KV 500 MVA POWER
TRANSFORMERS WITH OIL AND ERECTION, TESTING &
COMMISSIONING OF TRANSFORMERS
(VOLUME-II)
DRAWINGS
12
500
500
500