GUJARAT STATE ELECTRICITY CORPORATION LIMITED
ISO 9001:2008, ISO 14001:2004 and OHSAS 18001:2007 CERTIFIED
T HERMAL PO WER ST AT IO N, UKAI
UKAI DAM – 394680, DISTRICT : TAPI
Phone : 02624 - 233231, 233244 Fax : 02624 - 233300 (O) 233315 (S)
e-mail : ukaiceg@gebmail.com, ukaiaceg@gebmail.com, u k a i t p s @ g e b m a i l . c o m
W ebsite : www.gsecl.in
PRICE BID
T-3010
Supply of 500 / 200 KVA, 11 KV / 415 V, 3 Phase, Oil Filled, transformer suitable for outdoor
installation with off circuit tap changer.
1
THERMAL POWER STATION UKAI DAM DIST - TAPI - 394680
SCHEDULE-B (Price Bid)
Description : Supply of 500 / 200 KVA, 11 KV / 415 V, 3 Phase, Oil Filled transformer suitable for outdoor installation with off circuit tap changer.
Reference No.: T-3010
E-Urja RFQ No.: 10905
Sr.
No.
1
2
Description of materials with details
of Specifications
11 / 0.440 KV, 500 KVA, ONAN,
TRANSFORMER, HV (3 - PHASE),
LV(3 PHASE & NEUTRAL) WITH OFF
LOAD TAP CHANGER, OIL FILLED
SUITABLE FOR OUT DOOR
APPLICATION
11 / 0.440 KV, 200 KVA, ONAN,
TRANSFORMER, HV (3 - PHASE),
LV(3 PHASE & NEUTRAL) WITH OFF
LOAD TAP CHANGER, OIL FILLED
SUITABLE FOR OUT DOOR
APPLICATION
Quantity
Require
d
UOM
1
Num
ber
1
Num
ber
Quanti
ty
Offere
d by
Tender
er
Unit
Ex-W
orks
In
Rs.
Packaging
and
Forwardin
g Charges
per Unit in
Rs.
Excise
Duty
per
unit in
Rs.
Sales
Tax
per
unit in
Rs.
Insuranc
e
Charges
per unit
in Rs.
Freight
Charg
es per
unit in
Rs.
Unit
End
Cost
Price
in
Rs.
Total
End
Cost
Price in
Rs.
Detailed technical specifications : As per following Annexure.
[1] Annexure-I
→ GTP for 200 KVA / 500 KVA distribution transformers.
[2] Annexure-II
→ Technical specifications / Technical terms & conditions.
2
ANNEXURE – I
GUARANTEED & OTHER PARTICULARS FOR DISTRIBUTION TRANSFORMERS
(To be furnished by the Manufacturer in separate sheet as per this format)
Sr. No.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
21.
22.
23.
Description
Make & Manufacturer
Type of Transformer
Voltage Ratio
Rating in kVA
System voltage (max.)
Rated voltage HV
Rated voltage LV
Line current HV
Line current LV
Frequency
No. of Phases
Connection HV
Type of cooling
Noise level at rated voltageand frequency
Min. No. of coil per limb
Connection LV
Vector group
% Impedance at 75 deg.C.
Regulation at
a) Unity P.F.
b) 0.8 P.F. at 75 deg.C.
Tap changing arrangement (off load) & to be provided
on HV side for HV variation.
Flash Test
(a) HV 28 kV / 50 HZ for 1min.
(b) LV 3 kV/50 Hz for 1 min.
Over potential Test Double Voltage & Double
frequency for 1 minute
Efficiency at 75 deg.C.
a) Unity P.F. &
200 kVA
500 kVA
Voltamp, ABB or CGL
Voltamp, ABB or CGL
3 phase, oil filled, Suitable for outdoor installation
11000/433V
11000/433V
200 kVA
500 kVA
12 kV
12 kV
11 kV
11 kV
433 - 250 V
433 - 250 V
10.5 A
26.25 A
266.0 A
665.0 A
50 c/s +/- 5%
50 c/s +/- 5%
Three
Three
Delta
Delta
ONAN
ONAN
45 db
45 db
8 coil per limb
10 coil per limb
Star(Neutral brought out)
Star (Neutral brought out)
Dyn-11
Dyn-11
< 4.75%
< 4.75%
As per IS tolerance
As per IS tolerance
+2.5 % to
-7.5% in step of 2.5 %
To be withstand
+2.5 % to
-7.5% in step of 2.5 %
To be withstand
To be withstand
To be withstand
3
24.
25.
26.
27.
28.
29.
30.
31.
32.
33.
34.
b) 0.8 P.F.
1) 125% load
As per IS tolerance.
2) 100% load
3) 75% load
4) 50% load
5) 25% load
Core Material used and Grade
CRGO
Amorphous
a) Flux density
1.69 T
1.69 T
Maximum temperature rises above ambient temp. of
50 deg C
a) windings by resistance method
40 Deg. C
b) Oil by Thermometer
35 Deg. C
Magnetizing (No load) Current at
a) Normal Voltage
<3% of FLC <2% of FLC
b) Maximum Voltage
<6% of FLC <5% of FLC
Core loss in watts
AMT
CRGO
No load losses
124
311
Full load losses in watts at 75 deg.C.
2312(CRGO)
Total losses at 100% load at 75 deg. C
With in IS tolerance.
Total losses at 50% load at 75 deg. C
With in IS tolerance.
Current density used for
a) HV winding.
< 2.5 A/sq.mm (for Copper
Cond)
b) LV winding.
<1.60 A/sq.mm
(for Aluminium Cond)
Clearances
a) Core & LV
b) LV & HV
c) HV Phase to Phase
255 mm
d) End insulation clearance to Earth
e) Any point of winding to tank
Inter layer insulation provided in design for
Epoxy dotted Kraft Paper
1) Top & bottom layer
2) In between all layer
3) Details of end insulation
4)Whether wedges are provided at 50% turns of the
HV coil
Paint
Epoxy-632
As per IS tolerance
CRGO
1.69 T
Amorphous
1.69 T
40 Deg. C
35 Deg. C
<3% of FLC <2% of FLC
<6% of FLC <5% of FLC
AMT
CRGO
292
730
4420(CRGO)
With in IS tolerance.
With in IS tolerance.
< 2.5 A/sq.mm
(for Copper Cond)
<1.60 A/sq.mm (for Aluminium
Cond)
255 mm
4
35.
Fittings(accessories)
36.
Particulars of Bushings HV / LV
1) Type IS-3347/IS-1180
2) Rating as per I.S.
Rating & Diagram Plate, Terminal marking plate, Lifting &
jacking lugs, Silica gel breather, Bottom Drain cum Filter valve,
Top Filter valve, Thermometer pocket, Conservator with oil filling
hole and drain plug, flat Rollers, Explosion Vent with double
diaphragm, Oil Temperature Indicator, Winding Temperature
Indicator, Buchholz Relay with 2 Nos. shut-off valves, Magnetic
Oil Level Gauge, Marshalling Box.
Note : The following shall be specifically confirmed
1.
Whether the offer conforms to the limits of impedance mentioned in the specification
2.
Whether the offer conforms to the limits of temperature rise mentioned in the Specification
3.
Whether the losses of the transformers offered are within the limits specified
4.
Whether the transformer offered is already type tested for the design and test reports enclosed.
5.
Bidders are requested to quote the prices of the Transformer for core materials of CRGO & Amorphous separately.
5
ANNEXURE-II
Technical terms & conditions
TECHNICAL SPECIFICATION FOR OUTDOORS TYPE DISTRIBUTION TRANSFORMERS OF THREE PHASE 11 KV 433 - 250V
CLASS UPTO AND INCLUDING 500 KVA WITH CRGO / AMORPHOUS METAL CORE
1.0
SCOPE:
This specification covers engineering, manufacture, assembly, stage testing, inspection and testing before supply and delivery at site of oil
immersed,
Naturally cooled 3 phase 11 kV/433 - 250 V Distribution Transformers for outdoor use.
1.1
It is not the intent to specify completely herein all the details of the design and construction of equipment. However the equipment shall
confirm in all respects to high standards of engineering, design and workmanship and shall be capable of performing in continuous
operation up to the Bidder’s guarantee, in a manner acceptable to the purchaser, who 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
equipment 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 Bidder’s supply irrespective of whether those are specifically brought out in this specification and / or the
commercial order or not.
1.2
STANDARD RATINGS:
The Standard Ratings shall be 200 / 500 KVA.
2.0
STANDARDS:
2.1.
The materials shall conform in all respects to the relevant Indian / International Standard Specification, with latest amendments thereof;
some of them are listed below:
Indian Standard
ISS -2026/1977
IS 12444
ISS -3347/1967
ISS-335/1983
ISS - 5484
ISS - 9335
ISS - 1576
ISS- 6600/1972
ISS-649
Title
Specification for Power Transformer
Specification for Copper wire rod
Specification for porcelain Transformer bushing
Specification for Transformer Oil
Specification for Al Wire rods
Specification for Insulating Kraft Paper
Specification for Insulating Press Board
Guide for loading of oil Immersed Transformers
Testing of Steel Sheets & Strips For Magnetic circuits
International & Internationally recognized standard
IEC 76
ASTM B-49
DIN 42531,23,3
BS 148, D-1473, D-1533- 1934 IEC Pub 296-1969
ASTM B - 233
IEC 554
IEC 641
IEC 76
6
ISS-6162(Part-I&II)
ISS- 3401
ISS-1866
Paper covered Aluminum Conductor
Silica gel
Code of practice for maintenance & supervision of
Mineral insulating oil in equipment.
Material conforming to other internationally accepted standards, which ensure equal or higher quality than the standards mentioned above,
would also be acceptable. In case the Bidders who wish to offer material conforming to the other standards, salient points of difference
between the standards adopted and the specific standards shall be clearly brought out in relevant schedule. Four copies of such standards
with authentic English translations shall be furnished along with the offer.
3.0
SYSTEM DETAILS:
The transformers shall be suitable for outdoor installation with 3 phase 50 Hz, 11 KV system in which the neutral is effectively
earthed and they should be suitable for service under fluctuations in supply voltage up to plus 10% to minus 15%.
3.1.
SERVICE CONDITIONS:
The Distribution Transformers to be supplied against this specification shall be suitable for satisfactory continuous operation under the
following climatic conditions as per IS 2026 (Part - I) Latest Revision
i)
ii)
iii)
iv)
v)
vi)
(vii)
(viii)
(ix)
(x)
(xi)
Location
Max ambient air
temperature (deg.C)
Min. ambient air
temperature (deg.C.)
Max average daily ambient
air temperature (deg.C)
Max. yearly weighed average
ambient temperature (deg.C)
Max. altitude above
mean sea level (Meters)
Maximum relative humidity:
Average thunder storm days/annum
Average rainy days per annum
Average annual rain fall
Number of months of tropical monsoon
:
At Ukai TPS, Dist- Tapi in Gujarat
:
50
:
0
:
45
:
40
:
:
:
:
:
:
1000
0 to 100%
15 nos
90 days
1000/1100 MM
3 Months.
The equipment shall be for use in moderately hot and humid tropical climate, conducive to rust and fungus growth.
7
5.1.1 MATERIAL - CRGO/ AMORPHOUS METAL:
a)
i)
vi)
CRGO Material:
The core shall be of NEW high grade cold rolled grain annealed steel lamination having low loss and good grain properties, coated with
hot oil proof insulation, bolted together and to the frames firmly to prevent vibration or noise. The complete design of core must ensure
permanency of the core losses with continuous working of the transformers. The value of the maximum flux density allowed in the design
and grade of lamination used shall be clearly stated in the offer.
Core Clamping for CRGO:
1. MS channel shall be used on top and bottom
2. Core Channel on LV side to be reinforced at equidistance, if holes / cutting is done for LT lead in order to avoid bending of channel.
3. MS Channels shall be painted with varnish or oil-resistant paint.
The transformers core shall be suitable for over fluxing (due to combined effect of voltage and frequency) up to 12.5% without injurious
heating at full load conditions and shall not get saturated. The Bidder shall furnish necessary design data in support of this situation.
The nominal flux density in any part of the core shall not exceed 1.69 Tesla at 1.0 p.u.voltage and 1.9 Tesla at 1.1 p.u.voltage. The vendor
shall furnish necessary design data in support of this stipulation.
No load current shall not exceed 3% of full load current and will be measured by energizing the transformer at 433 volts, 50 c/s on the
secondary. Increase of voltage of 433 volts by 12.5% shall not increase the No load current by Max. 6% of full load current. Test for
magnetic balance by connecting the LV phase by phase to rated phase voltage and measurement of an, bn, cn voltage will be carried out.
Clamping and Tie-rods shall be made from HT steel & shall be parkarised.
b)
AMORPHOUS METAL:
i)
The core shall be high quality amorphous ribbons having very low loss formed into wound cores of rectangular shape, bolted together to
the frames firmly to prevent vibration or noise. The complete design of core must ensure permanency of the core loss with continuous
working of the transformers. The value of the flux density allowed in the design shall be clearly stated in the offer. Curve showing the
properties of the metal shall be attached with the offer.
Core Clamping for Amorphous metal Transformers
1. Core clamping shall be with top and bottom U-shaped core clamps made of sheet steel clamped HT steel tie rods for efficient
clamping.
2. MS core clamps shall be painted with varnish or oil-resistant paint.
3. MS rods shall be used as tie rods.
4. Suitable provision shall be made in the bottom core clamp / bottom plate of the transformer to arrest movement of the active part.
The transformers core shall be suitable for over fluxing (due to combined effect of voltage and frequency) up to 12.5% without injurious
heating at full load conditions and shall not get saturated. The Bidder shall furnish necessary design data in support of this situation.
No load current shall not exceed 2% of full load current and will be measured by energizing the transformer at 433 volts, 50 c/s on the
secondary. Increase of voltage of 433 volts by 12.5% shall not increase the No load current by Max. 5% of full load current. Test for
magnetic balance by connecting the LV phase by phase to rated phase voltage and measurement of an, bn, cn voltage will be carried out.
ii)
iii)
iv)
v)
ii)
iii)
iv)
8
Note : "Equal weightage shall be given to the transformers with amorphous metal core & CRGO".
5.2
WINDINGS:
5.2. a Materials : Super enamel covered copper Conductor or Double paper covered copper conductor shall be used for 11KV / 500 KVA or
Double paper covered aluminum conductor shall be used for 11 KV / 200KVA class transformer. A mix of copper & aluminum
conductors for HV & LV winding will not be permitted.
5.2. b. Current density for HV and LV shall not be more than 2.5 A/sq.mm. for copper and 1.60 A/sq.mm. for aluminum conductor. (However,
+5% tolerances for LV winding is permissible)
5.2. c. LV winding shall be in even layers so that neutral formation will be at top. The winding shall be of one or more rectangular conductors
insulated from each other to reduce eddy current losses. The tolerances on the size of the conductor shall be as per IS-6160, specification
for rectangular conductors. If the active axial length of the coil is more than 350 mm, an axial duct, of 4 mm is provided between the LV
coil layers. The materials used for providing duct shall be non-compressible material such as treated wood permali, etc.
5.2. d. The winding construction of single HV coil wound over LV coil is preferable.
This is generally of round wire and coils are in form of packets and a number of coils are connected in series to achieve the necessary
voltage ratio. The number of coil per limb shall depend upon the necessary cooling surface and mechanical strength.
An axial duct of 3 mm is to be provided if the radial thickness of coils is more than 50 mm and/or the axial length of individual coil is more
than 80mm. The radial duct shall be adequate for free circulation of oil as well as to withstand voltage between adjacent coils. The inter –
layer insulation shall be of epoxy coated paper or a minimum 4 layers of 2 mil ( 0.05mm) paper of approved manufactures.
5.2.e. Inter layer insulation shall be Epoxy dotted Kraft Paper.
5.2.f. Proper bonding of inter layer insulation with the conductor shall be ensured. Test for bonding strength to be conducted.
5.2.g. Dimensions of winding coils are very critical. Dimensional tolerances for winding coils shall be with in limits as specified in GTP.
5.2.h. Taps shall be made on the primary winding for -7.5% to +2.5% for HV variations.
5.2.e. INSULATION MATERIAL & CLEARANCES:
5.2..e(i).Materials Electrical grade insulating craft paper of Triveni / Ballarpur / Cauvery or equivalent make subject to approval of the purchaser
shall be used. Similarly Press Board of Senapaty, Whitelay or Raman make or equivalent subject to the approval of the purchaser shall be
used. Perma wood or Haldi wood blocks shall be used for top and bottom yoke insulation.
INTERNAL CLEARANCES
Location
Where active length of LV coil
350 mm or less.
More than 350 mm
(i) LV coil to core circle
3
4
(ii) LV coil to HV coil
9
11
(iii) HV coil phase to phase
10 For 11KV Class
(a)
10
(iv)HV coil / HV leads to
inside surface of tank
(a)
30
30 for 11KV Class
9
5.2.1 OIL:
5.3
The insulating oil shall comply with the requirements of relevant standards IS 335 / 1993 or BS 148 or REC 39/1993. Oil shall be filled
under vacuum of 250 tolr. +/- 5 %.
LOSSES:
The bidder should guarantee individual No load loss and load loss without any positive tolerance. The bidder should also guarantee the
total losses at 50% load condition (50% of rated kVA rating at rated voltage and frequency and at 75 deg centigrade without any positive
tolerance.
The losses shown in GTP are maximum allowable and there would not be any positive tolerance.
Bids with higher losses than the above specified values would be treated as Non-responsive.
5.3.1. Percentage Impedance:
Voltage
Ratio
11000/433 - 250 V
11000/433 - 250 V
kVA
Rating in KVA
200
500
Percentage
Impedance
≤ 4.75 %
≤ 4.75 %
% impedance shall be subject to tolerance specified in IS: 2026 – 1977.
Bids not meeting the limits indicated above will be treated as non-responsive.
5.3.2 Temperature rise:
The temperature rises over ambient shall not exceed the limits described below:
Top oil temperature rise measured by thermometer
Winding temperature rise measured by resistance
5.4
:
:
35 deg.C
40 deg.C
Bids not meeting the above limits of temperature rise will be treated as non-responsive.
PENALTY FOR NON PERFORMANCE:
5.4.1. Transformers with temperature rise and impedance beyond guaranteed values:
5.4.2. Purchaser reserves the right to reject the transformer during the test at supplier’s works, if the temperature rise exceeds the guaranteed
values.
5.4.3. Purchaser reserves the right to reject any transformer during the test at supplier’s works, if the impedance values differ from the guaranteed
values including tolerance.
5.5
INSULATION MATERIAL:
a) Material : Electrical grade insulation Kraft Paper of standard make or better material subject to approval of the purchaser. Pressboard of
standard make or better material subject to approval of purchaser.
10
b) All spacers, axial wedges / runners used in windings shall be made of pre-compressed Pressboard − solid, conforming to type B 3.1 of
IEC 641-3-2. In case of cross-over coil winding of HV all spacers shall be properly sheared and dovetail punched to ensure proper
locking. All axial wedges / runners shall be properly milled to dovetail shape so that they pass through the designed spacers freely.
Insulation shearing, cutting, milling and punching operations shall be carried out in such a way, that there should not be any burr and
dimensional variations.
5.6
TANK:
The transformer tank can be with radiator fins.
FOR RECTANGULAR PLAIN TANK:
i.
ii.
iii.
iv.
v.
vi.
vii.
viii.
ix.
x.
The transformer tank shall be of robust construction rectangular in shape and shall be built up of tested MS sheets. The tank shall be made
of prime quality MS sheet with necessary stiffener to withstand the pressure built in during the expansion of oil due to temperature rise.
The exterior of the transformer tank and other ferrous fitting shall be thoroughly cleaned, scraped / sand blasted and given a priming coat
and two finishing coats of durable oil and weather resistant paint of light admiralty grey conforming to color code No. 697 of IS-5/2978.
The internal clearance of tank shall be such that, it shall facilitate easy lifting of core with coils from the tank without dismantling LV
bushings.
All joints of tank and fittings shall be oil tight and no bulging should occur during service. The tank design shall be such that the core and
windings can be lifted freely. The tank plate shall be of such strength that the complete transformers when filled with oil may be lifted
bodily by means of lifting lugs. Inside of tank shall be painted with varnish / hot oil.
Manufacturer should carry out all welding operations as per the relevant ASME standards.
The four walls of the tank shall be made of Two “L” shaped sheets (without joints) fully welded at the corners from inside and outside of
the tank for withstanding a pressure of 0.8 kg/cm2 for 10 minutes.
The tank shall be reinforced by welded angle on all the outside walls on the edge of the tank to form two equal compartments. Permanent
deflection when the tank without oil is subject to a vacuum of 525 mm of mercury for rectangular tank and 760 mm of mercury for round
tank, shall not be more than 5 mm up to 750 mm length and 6 mm upto 1250 mm length. The tank shall further be capable of
withstanding a pressure of 0.8 kg/sq.cm (g) and a vacuum of 0.3 kg/sq.cm(g) without any deformation.
The radiators can be tube type or fin type or pressed steel type to achieve the desired cooling to limit the specified temperature rise. The
transformer shall be capable of giving continuous rated output without exceeding the specified temperature rise. Bidder shall submit the
calculation sheet.
Lifting lugs : 4 Nos. welded heavy duty lifting lugs of MS plate 8 mm thick (min) suitably reinforced by vertical supporting flat welded
edgewise below the lug on the side wall.
Pulling lugs : 4 Nos. of welded heavy duty pulling lugs of MS plate 8 mm thick (min) shall be provided to pull the transformer
horizontally.
Top cover fixing bolts of G.I adequately spaced and 6 mm Neoprene bonded cork gaskets conforming to IS 4253 part-II shall be placed
between tank and cover. The bolts outside tank shall have 2 flat washers & one spring washer.
11
5.6.8. CONSERVATOR
a. On Transformers of all ratings with rectangular plain tank the provision of conservators is obligatory.
b. When a conservator is provided, oil gauge and the plain or dehydrating breathing devise shall be fixed to the conservator which shall
also be provided with a drain plug and a filling hole (1¼" normal size thread) with cover. The capacity of a conservator tank shall be
designed to contain 10% of the total quantity of oil and its contraction and expansion due to temperature variations. Normally 3%
quantity of total oil will be contained in the conservator. In addition the cover of main tank shall be provided with an air release
plug to enable air trapped within to be released, unless the conservator is so located as to eliminate the possibility of air being trapped
within the main tank.
5.6.9. BREATHER:
Breather shall be screwed type. It shall have die cast aluminum body & further, inside container for silica gel shall be of tin sheet,
Volume of Silica gel breather shall be 0.5 Kg. Inverted U-shape pipe shall be used for connection of breather.
5.7
SURFACE PREPARATION & PAINTING
5.7.1. GENERAL:
5.7.1.1 All paints
following:
a)
b)
c)
d)
e)
shall be applied in accordance with the paint manufacturer’s recommendations. Particular attention shall be paid to the
Proper storage to avoid exposure as well as extremes of temperature.
Surface preparation prior to painting.
Mixing and thinning
Application of paints and the recommended limit on time between coats.
Shelf life for storage.
5.7.1.2 All paints, when applied in a normal full coat, shall be free from runs, sags, wrinkles, patchiness, brush marks or other defects.
5.7.2. PAINT MATERIAL:
Followings are the types of paint that may be suitably used for the items to be painted at shop.
5.7.2.1 Heat resistant paint (Hot oil proof) for inside surface.
5.7.2.2 For external surfaces one coat of Thermo Setting Powder paint or 1 coats of Zinc chromate primer followed by 2 coats of Synthetic
Enamel / Polyurethene base Paint These paints can be either air drying or staving.
5.7.2.3 The color of the finishing coats shall be dark admiral gray conforming to No. 632 of IS-5 of 1961
12
5.7.3. PAINTING PROCEDURE:
5.7.3.1 To the maximum extent practicable the coats shall be applied as a continuous film of uniform thickness and free of pores. Overspray, skips,
runs, sags and drips should be avoided. The different coats may or may not be of the same colour.
5.7.3.2 Each coat of paint shall be allowed to harden before the next is applied as per manufacturer’s recommendation.
5.7.3.3 Particular attention must be paid to full film thickness at edges.
5.7.3.4 The painted surface shall be tested for paint thickness.
5.7.3.5 The painted surface shall pass the Cross Hatch Adhesion test, as per the relevant ASTM standards.
NOTE : Supplier shall guarantee the painting performance requirement for a period of not less than 5 years.
5.8.
BUSHINGS:
5.8.1 The H.V, LV porcelain bushing and metal parts shall be as per following IS
1) IS 5621/1980 – hollow insulators.
2) IS 7421/1988 – Porcelain transformer bushing up to 11KV.
3) IS 2099/1986 – bushing for A.C voltage above 1kv.
4) IS 3347/1988 – porcelain transformer bushing.
The metal parts shall be made from drawn or rolled quality tinned brass or electroplated. The arrangement of bushing at top plate will only
be acceptable. HV bushings are to be installed on turret, flange and gaskets to prevent eventual entry of water. Bushings having type tested
as per IS 3347 and approved by the Board shall only be acceptable.
Note: Embossing showing the Manufacturer’s name should be clearly visible, even after fixing the same on Transformer.
5.8.2 The bi-metallic connectors shall have to be fitted on HV/LV terminals having capacity of double the size of rated HV/LV current of
transformer.
5.8.3 INTERNAL CONNECTION:
(a)
HV winding:
i) In case of HV winding all jumpers from winding to bushing shall have cross section larger than winding conductor.
ii) Inter coil connection shall be done by brazing.
iii) In case of AL/CU winding Delta joint shall be with brazing only.
iv) Lead from Delta joint shall be connected to bushing rod by brazing only.
(b)
LV Winding:
LV star point shall be formed of AL/CU flat of sufficient size and length. Lead from winding shall be connected to the flat by brazing.
Firm connection of LV winding to bushing shall be made of adequate size of “L” shape flat. Connection of LV coil lead to “L” shape flat
shall be made by brazing. The "L"Shape flat shall be of copper for copper winding & Alluminium of Alluminium winding. “L” shape
flat/lug shall be clamped to LV bushing metal part by using nut, locknut and washer.
13
5.9.
TANK BASE CHANNEL:
For numbers of plain bi-directional rollers with cross channels for platform mounting.
5.10. TERMINAL MARKINGS:
(i)
High voltage and Low voltage phase windings shall be marked both in the terminal boards inside the tank and on the outside with capital
letter 1U, 1V, 1W and low voltage winding for the same phase marked by corresponding small letter 2u, 2v, 2w. The neutral point terminal
shall be indicated by the letter 2n. Neutral terminal to be brought out and connected to local grounding terminal by an Earthing strip.
(ii)
Marking of GSECL and Sr. No. of transformer will be engraved in addition to above on top cover near lifting lug towards Neutral side.
(iii)
The name of the company, order no., capacity, month and year of manufacturing GSECL, Sr. No. shall be engraved on tank of transformer
just below the name plate clearly visible. The engraving can be done on separate plate which shall be firmly welded to main tank and shall
form integral part of the tank.
5.11 FITTINGS:
The following standard fittings shall be provided.
a) Two earthing terminal (stud and bolts should be properly galvanized and confirm to IS: 1363/1967 and IS : 1367/1961 and latest
amendment thereof.
b) Two lifting lugs to lift core assembly.
c) Two lifting lugs to lift complete transformer
d) Crimping type cable sockets for 200 / 500 KVA transformers with suitable G.I. bolts and nuts and washer to fix the same to LV
terminals.
e) Rating and terminal marking plates.
f) Unidirectional flat rollers.
g) Oil level gauge with toughened glass with minimum marking.
h) Thermometer pocket in according to ISS: 3580.
i) De-hydrating breather.
j) Air release plug on the transformer tank to release tapped air inside the tank when filling oil through conservator.
k) One drain cum sampling valve.
l) One filter valve on the supper top side of the tank
m) Lifting lugs for tank cover.
n) Inspection hole for 500 KVA
5.12 FASTENERS:
a. All bolts, studs, screw threads, pipe threads, bolt heads and nuts shall comply with the appropriate Indian Standards for metric threads,
or the technical equivalent.
b. Bolts or studs shall not be less than 6 mm in diameter except when used for small wiring terminals.
c. All nuts and pins shall be adequately locked.
d. Wherever possible bolts shall be fitted in such a manner that in the event of failure of locking resulting in the nuts working loose and
falling off, the bolt will remain in position.
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e. All ferrous bolts, nuts and washers placed in outdoor positions shall be treated by hot dip galvanizing, except high tensile steel bolts
and spring washers which shall be electro-galvanized / plated. Appropriate precautions shall be taken to prevent electrolytic action
between dissimilar metals.
f. Each bolt or stud shall project at least one thread but not more than three threads through the nut, except when otherwise approved for
terminal board studs or relay stems. If bolts nuts are placed so that they are inaccessible by means of ordinary spanners, special
spanners shall be provided.
g. The length of the screwed portion of the bolts shall be such that no screw thread may form part of a shear plane between members.
h. Taper washers shall be provided where necessary.
i. Protective washers of suitable material shall be provided front and back or the securing screws.
5.13
MOUNTING ARRANGEMENT:
For numbers of plain bi-directional rollers with cross channels for platform mount
5.14
OVERLOAD CAPACITY:
The transformers shall be suitable for loading as per IS: 6600 / 1972
5.15 GUARANTEE FOR THE TRANSFORMERS:
1)
Guarantee period shall be 60 months from the date of supply. If any transformer fails during this guarantee period, the supplier
shall repair the same at his cost at his works.
2)
The supplier situated outside Gujarat State shall have to establish suitable and adequate arrangement for repairing and testing of
failed transformer in Gujarat State at his cost.
6.0.
6.1.
TESTS:
a) All the equipment offered shall be fully type tested by the bidder or his collaborator as per the relevant standards. The type test must
have been conducted on a transformer of same design. The Bidder shall furnish sets of type test reports along with the offer.
b) The test certificates for all routine and type tests for the transformers and also for the bushings and transformer oil shall be submitted
with the bid.
ROUTINE TESTS:
1.
Ratio, polarity and phase sequence.
2.
No Load current and losses at service voltage and formal frequency
3.
Load losses at rated current and normal frequency
4.
Impedance Voltage test
5.
Resistance of windings at each tap, cold (at or near the test bed temp.)
6.
Insulation resistance
7.
Induced over voltage withstand test.
8.
Separate source voltage withstand test.
9.
Neutral current measurement
10.
Oil samples to comply with IS 1866.
11.
Measurement of no load losses and magnetizing current at rated frequency and 90%, 100% and 110% voltage
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6.2
TESTS AT SITE : The purchaser reserves the right to conduct all tests on Transformer after arrival at site and the manufacturer shall
guarantee test certificate figures under actual service conditions.
6.4.
ACCEPTANCE TESTS:
The transformers shall be subjected to the following routine / acceptance test in presence of purchaser’s representative at the place of
manufacture before dispatch without any extra charges. The testing shall be carried out in accordance with IS: 1180 and IS: 2026.
a. Checking of weights, dimensions, fitting and accessories, tank sheet thickness, oil quality, material, finish and workmanship as per GTP /
QA Plan and contract drawings.
b. Physical verification of core coil assembly and measurement of flux density of one unit of each rating, in every inspection with reference to
short circuit test report.
c. All tests as specified in clause 6.1
6.5
Transformer Oil:
The transformer oil to be filled shall be I.S.I. marked confirming to REC Specification 39/1985 (R-1993) and I.S. 335/1993 with latest
amendments.
To ascertain the quality of the transformer oil the original manufacturers’ test report shall be submitted at the time of inspection.
6.6
TOLERANCES:
Unless otherwise specified herein the test value of the transformers supplied would be within the tolerance permitted in the relevant
standards. No positive tolerance is allowed on guaranteed No Load and Load losses.
7.0.
8.0.
i)
ii)
9.0
9.1
9.2
INSPECTION:
All tests and inspection shall be made at the place of manufacturer and unless other wise especially agreed upon the manufacturer and the
purchaser at the time of purchase. The manufacturer shall afford the inspector representing the purchaser all reasonable facilities, without
charge to satisfy him that the material is being furnished in accordance with specification.
The manufacturer shall provide all services to establish and maintain quality of workman ship in his works and that of his sub-contractors
to ensure the mechanical / electrical performance of components, compliance with drawings, identification and acceptability of all
materials, parts and equipment as per latest quality standards of ISO 9000.
DOCUMENTATION:
The Bidder shall furnish along with the bid the dimensional drawings of the items offered indicating all the fittings.
Dimensional tolerances
Weight of individual components and total weight.
PACKING & FORWARDING:
The packing shall be done as per the manufacturer’s standard practice. However, it should be ensured that the packing is such that, the
material would not get damaged during transit by Rail / Road / Sea.
The making on each package shall be as per the relevant IS.
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10.0. DRAWINGS :
One copy of the dimensional drawing and internal construction drawing of each ratting transformer shall be submitted with the tender.
These drawings shall be of A-3 (420 x 297 mm) size only. Guaranteed and other technical particulars of the transformers as per the tender
shall also be submitted in A-4 size for our approval. In the Performa attached with tender only.
11.0 GTP- GUARANTEED AND OTHER PARTICULARS FOR TRANSFORMERS:
To be filled in and submitted by the tenderer in the Performa attached with the tender.
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For any deviation from the specification, which is not specifically brought out in the schedule of deviations, the offer may be liable for
rejection. The deviation brought out in the schedule shall be supported by authentic documents, standards and clarifications; otherwise the
offer may be liable for rejection.
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The tenderer shall submit the list of orders for similar type of equipments, executed of under execution during the last three years, with full
details in the schedule of Tender’s experience (Schedule ‘C’) to enable the purchaser to evaluate the tender.
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TENDER DRAWINGS TO BE ENCLOSED:
i)
G. A. Drawing.
ii)
Internal Construction Drawing.
iii)
Name plate drawing
iv)
Technical Details Sheet.
v)
HT/LV Bimetallic connectors.
vi)
Drain cum sampling Valve Drawing.
vii)
Drawing for month & year to be written on conservator tank & body.
viii) Core details drawing
ix)
Short circuit capacity calculation sheet
x)
Cooling capacity calculation
The above drawings are illustrative. However, the tenderer may submit their own drawing if they so desires. The bidder shall submit above details
along with offer as well as before offering the prototype transformer.
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NOTE: (1)
Party has to give inspection call for Routine Testing as per IS-2026 at their works.
(2)
The transformer supplied by the party shall be guaranteed for 12 months from the date of commissioning / 18 months from the date of
dispatch, whichever is earlier.
(3)
Cable Glands and cable lugs for Cable box shall not be in the party scope.
(4)
Party shall furnish weight and dimensions after finalizing / freezing the design and parameters after the detailed engineering. Party shall
furnish efficiency and regulations.
(5)
Make for above item : Voltamp, ABB or CG make only.
(6)
Tendere shall have to furnish the details regarding efficiency, regulation HV / LV current rating and no load / full load loss of the relevant
transformer in Technical particulars with Technical Bid.
Yours Faithfully,
CHIEF ENGINEER [GEN.]
GSECL:TPS:UKAI
(Signature of the Tenderer)
(With Company`s Round Seal)
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