SCHEDULE OF WORK
Name of work: Supply of 1 x 1000 KVA, 6KV/415 V, 3-phase, 50 Hz Indoor Type,
Cast Resin, Dry Transformer for augmentation of the existing Substation of IACS
(Phase-III), Jadavpur, Kolkata.
Sl. No.
Item of Work
Rate
Qty
(Rs.
1.
Supply of 1000 KVA, 3-phase, 50 Hz, 6KV/
415Volt self cooled (Air-Natural) Cast resin,
dry type, step down, double wound copper,
indoor distribution transformer having Delta
primary and Star secondary, with Dyn11
vector group connection having neutral
brought out on star side with matching
percentage impedance, voltage ratio and
vector group etc (details of existing machine
data attached) i/c provision for terminating
cables on LT & HV side, fitted with
adequate size Cable End Boxes and
provided with temperature protection
devices and all other standard fittings etc. as 1 No
per attached specifications complete.
Note:
1.
2.
3.
4.
5.
6.
7.
Unit
P)
Amount
(Rs.
P)
each
The rate should be inclusive of all taxes, transportation charges including
transit insurance, loading & unloading at site etc as per enclosed
ANNEXURE. Nothing extra will be paid in addition to the quoted rate.
The firm should mention the model no, make and shall submit a printed
literature of the product with the technical bid positively.
The vendor should sign on all pages of the tender document along with
their company seal towards acceptance of all NIT conditions. Rates should
be written in the relevant space of the schedule of works (on the basis of
price derived from ANNEXURE) in figure and word both.
90% of the bill value will be made against successful delivery of materials
at site at IACS, Jadavpur, Kolkata on physical verification.
However, balance 10% will be kept as Security deposit with adjustment of
EMD which will be paid after twelve months on satisfactory performance of
the equipments. The security deposit may be accepted by performance bank
Guarantee also, if opted for by the vendor.
Guarantee certificate, users manual etc are required to be handed over to the
user after successful commissioning of the system.
Conditional/incomplete tenders or tender without EMD or EMD not in
proper form shall be summarily rejected.
Signature of bidder with seal
Specification for Cast Resin dry type transformer
1
2
3
A-General Data
Reference
Rated KVA
Rated Voltage
4
5
6
7
Rated Frequency
Class of Insulation
No of phases on the system
% impedance
8
9
10
11
Double wound or Single wound
Vector Group
Winding Materials
Taps Required
12
13
14
Tap change type
Type of Cooling
Neutral Terminal
15
Parallel Operation
16
17
18
19
Diagram requirement
Reference Ambient temperature
Temperature rise of windings above
the ambient temperature
Basic insulation level
20
Termination
1
2
3
B-constructional data
Type of Installation
Enclosure Protection
Standard Fittings
4
Testing
IS: 2026/1977 & IS: 11171/1985
1000 KVA
HV Side: 6 KV
MV Side: 415 volts
50 HZ
Class “F”
Three Phases
4.75% (the existing transformer is having
impedance of 4.75%)
Double wound
Dyn11
Electrolytic Copper
+5% to -10% in steps of 2.5% each on HV side
for variation with Off circuit tap links
Off-circuit tap link type
Air Natural
Neutral shall be brought out separately at the
secondary side.
Shall be suitable for parallel operation with the
existing transformers of similar type & capacity
Connection diagram plate is required
50 Deg C
90 Deg C (Hot Spot Temp.105 Deg. C above
Ambt.)
HV-60 KV (peak)
HV-Cable end box for 1x3C.185Sq.mm
Al/XLPE/Ar.11Kv.Cable
LV-Cable end box for 6x3.5C.400Sq.mm
Al/PVC/Ar.1.1Kv.Cable
Indoor
IP-23 (Indoor)
1) Rating & Technical plate
2) Earthing Terminals with lugs
3) 4Nos Flat, bi-directional rollers
4) Lifting lugs
5) Off circuit tapping links
6) HV termination-Cable end box
7) LV termination cable end box.
8) Door limiting switch
9) Marshalling box fitted with
temperature scanner suitable for 230V
A.C.
10) Vision window (panel) on HT side with
toughen glass
All Routine Tests as per IS 2026/1977 & IS
11171/1985 shall be conducted on transformer
and Test Report shall be submitted before the
delivery of the transformer. Nothing extra shall
be paid on this account.
Detailed Specification for Dry Type (Cast Resin) Distribution Transformer
1. SCOPE:
i) These specifications cover the design, manufacture and delivery of dry type
(Cast resin) distribution transformers with enclosures.
ii) The dry type distribution transformer shall be complete with all the
components and necessary accessories for the efficient and trouble free performance.
The details of various parts have been indicated in general in these specifications.
However, the parts not specified but required otherwise should form part of the
equipment.
2. GENERAL: The average ambient temperature shall be taken as 50 degree Celsius.
The transformers shall be suitable for installation in hot, humid monsoon area with
seasonal dry, duty conditions at Kolkata.
3. DESIGN DETAILS
i) Type: The Transformer shall be of indoor, three phase, Delta/Star
connected (Dyn11), Air cooled, cast resin Dry type totally enclosed step down
double copper wound distribution transformer. The transformer shall be as per IS:
2026/1977 & 11171 / 1985 with up to date amendments.
ii) Frequency / HT voltage variation:
a) Frequency: 50 HZ ± 3%
b) HT Voltage: 6 KV +10%
iii) Impendence:
The impedance of the transformer shall be of such values, so that the
transformers could be put to operate in parallel with the existing
Transformers of similar type.
iv) Temperature Rise:
The temperature rise of the transformer and the ceiling air temperature,
when tested at the rated KVA shall not exceed the following limit as
per ISS: 2026 pt. II/77 as amended up to date:
a) Winding: Average temperature rise as measured by
increased resistance of winding connected between
terminals 90°C.
b) Hot spot: Temperature rise as measured shall be 105°C.
above ambient
v) Insulation: Insulation class for winding and bushings of transformers shall
be as under as per IS: 2026 / 1977 with up to date amendments.
vi) Test Voltage Withstand
Nominal voltage
Impulse withstand voltage
6 KV
Not less than 60KV BIL
Double the
Power frequency
withstand voltage
20 KV (rms) in HT side & 3 KV
(rms) in LT side
vii) Parallel Operation: All the transformers as per detailed specifications shall be
capable of operating in parallel satisfactorily among themselves with an anticipated
25% unbalanced load. The transformer should have 4.75% of impedance on principal
tap at rated KVA at 75 degree centigrade.
TRANSFORMER CONSTRUCTION DETAILS:
The transformer shall be glass fibre reinforced Epoxy insulated cast resin type. The
features and construction detail of the transformer shall be in accordance with the
requirement detailed herein.
ENCLOSURES FOR EPOXY CAST RESIN TRANSFORMERS
a.
The epoxy cast resin transformer shall be housed in metal protective
housing having a degree of protection of IP-23 with perforated/ louvers
enclosure. The enclosure fabricated in two parts shall also
accommodate cable terminations of 6 KV side. The sheet steel
thickness of enclosure shall be at least 2.0mm with necessary reenforcement.
b.
The housing shall be provided with a door, which shall be inter-locked
such that it should be possible to open the door only when power
supply to the transformer is switched off. A suitable danger plate shall
be provided on the door/ cable end box cover etc.
c.
The enclosure shall be provided with suitable lifting lugs and necessary
hardware for mounting on the floor.
d.
Enclosure of the transformer should be openable on all sides except at
marshalling box cable end box for getting necessary access of
maintenance personnel.
MOUNTING ARRANGEMENTS:
For transformers, suitable 4 Nos. bidirectional rollers shall be provided with the body
for fixing the transformer on foundation. These rollers shall be such that the bottom of
the body is at a sufficient height above foundation for cleaning purpose.
TEMPERATURE INDICATOR:
a) Winding temperature indicator (WTI) scanner suitable for 230V. A.C.
A device (temp. scanner) for measuring the hot spot temperature of the
winding shall be provided. The accuracy class of winding temperature indicator shall
be ± 2 deg. C or better. It shall comprise of the following devices/features.
i) Temperature sensing element.
ii) Suitable local indicating instrument with maximum reading pointer
mounted. It shall have two potential free contacts, one for winding temperature high
alarm and one for trip when permitted temperature is exceeded.
EARTHING TERMINALS:
a) Two earthing ends suitable for connecting 25mm x 5mm copper strip shall
be provided at positions close to the two diagonally opposite bottom
corner of body. These grounding terminals shall be suitable for bolted
connection.
b) i) The neutral terminal of solid earthed winding shall be brought to the
ground level by MS grounding bar which shall be supported from the tank
by epoxy insulators.
ii) The end of grounding bar shall have two bolted neutral grounding
terminals and necessary accessories for connecting to ground network
through two copper strips.
CORE:
b) The core shall be constructed from high grade non-ageing cold rolled grain
oriented (CRGO) silicon steel laminations and protected against corrosion
by resin coat.
c) The design of the magnetic circuit shall be such so as to avoid static
discharges, development of short circuit paths within itself or to the
earthed clamping structure and the production of flux component at right
angles to the planes of laminations, which may cause local heating.
d) Adequate number of core bandages shall be provided to ensure uniform
compression of core lamination. The insulation of core clamp plates shall
be able to withstand a power frequency voltage of 2 KV (rms) for one
minute.
e) Core and windings shall be capable of withstanding shocks during
transport, installation, service and adequate provision shall be made to
prevent movement of core and winding during these conditions.
f) All steel sections used for supporting the core shall be thoroughly sand
blasted after cutting, drilling and welding shall be hot dip galvanised
/electro-galvanise.
g) Adequate provision shall be provided for lifting core and winding
assembly.
Windings:
a) The conductor shall be of electrolytic grade copper, free from scales & burrs.
b) The winding shall be insulated with material of Class-“F” or better.
c) Both the windings shall be encapsulated with epoxy cast resin under vacuum.
d) The windings should be moisture proof and non-inflammable.
NEUTRAL TERMINATION ARRANGEMENT:
The neutral terminal bar shall be brought out on a bushing similar to phase
terminals to form a 4 wire system for the 415 V. In addition to that; a parallel neutral
connection from star point shall be brought out to connect to the ground by a copper
flat of size 100mm x 12 mm. One CT is to be provided on neutral bus for providing
earth fault protection.
OFF CIRCUIT TAPPINGS
The tapping shall be bolted link type from +5% to -10% in steps of 2.5% each
on HV side for variation with Off circuit tap links with suitable arrangement for
locked in position.
PAINTING: All the surfaces to be painted shall be thoroughly cleaned from
soiled/dirt coating by sand blusting. Exterior surfaces shall be given two coats of light
coloured paint with good heat reflecting, corrosion and abrasion resisting
characteristics as per relevant IS of approved shade.
ACCESORRIES:
The offer shall be inclusive of all the accessories as mentioned below.
a)
Winding temperature indicator with fan alarm and trip contacts.
b)
Rating plate
c)
Lifting lugs on the body
d)
Rollers & base with provision for skidding in any direction.
e)
One cable end box complete with cable lugs for XLPE cable of 185 sq.
mm / 3 core on the HT side.
f)
LT side- 4 nos. required size of copper busbar size supported by
ceiling mounted epoxy resin insulator with cable end box for
accommodating 6 nos. 3-1/2 core 400 sq. mm Al. Conductor PVC
armoured Cable
g)
Earthing terminals: 2 nos.
TESTS on dry type Transformer:
Routine tests of the transformer shall be completely carried out in factory in
accordance with the IS: 11171 & 2026 and or any more tests, if considered necessary
to ensure that all the equipments are in accordance with the specifications. IACS
reserves the right to witness such tests. No extra payment will be made for such tests.
Routine tests shall include, but shall not be limited to: a)
Resistance measurement of all windings.
b)
Ratio tests for all sets of windings on each tap.
c)
Polarity and phase relation tests (Vector Group)
d)
No load (excitation) losses at rated voltage.
e)
Impedance and load losses at rated current.
f)
Exciting current at 100% and 110% of the rated voltage.
g)
Applied potential tests
h)
Induced potential tests.
i)
Insulation resistance test.
j)
Heat run test
Copies of test certificates for the type tests & routine tests along with certified
drawings as per ISS of transformer shall be furnished by the tenderer along
with the transformer.
Specification for Cast Resin Dry type Transformer
(To be filled up by the bidder)
1
2
3
4
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Make
Model No.
Rated KVA
Rated Voltage
Rated Frequency
Class of Insulation
% impedance
No of phases on the system
Double wound or Single wound
Vector Group
Winding Materials
Type of Tap setting: On load/Off
load
Tap setting on HT or LT side
No. of Tap settings steps and %
variations
Type of Cooling
Whether Neutral brought out
separately at secondary side
Whether suitable for Parallel
Operation with the existing
transformer of same type & capacity
having % impedance of 4.75%.
Diagram provided or not
Reference Ambient temperature
Temperature rise of windings
( above the ambient temperature)
Regulation at rated output and 0.8
pf , 0.9 pf and unity pf mentioning
% resistance and % reactance drop
Impedance at rated KVA and at
75°C
Exciting current with rated voltage
& frequency
No load losses at 75°C , rated
voltage and frequency
Total losses at 75°C, 0.8 pf and ½, ¾
and full rated KVA.
Efficiency at 75°C, 0.8 pf and ½, ¾
and full rated KVA.
Efficiency at 75°C, unity pf and ½,
¾ and full rated KVA.
26
27
28
29
30
31
32
33
34
35
36
37
38
Load at which maximum efficiency
occurs in % of full load
Maximum efficiency at %
Type of installation (Indoor or
Outdoor)
Enclosure protection (IP)
Enclosure sheet metal thickness
Induced over voltage withstand test
(twice rated voltage at 100 Hz for 1
min.)
Separate source voltage withstand HV:
test
LV:
Flux density
HV:
LV:
Current density
Core & coil Assy. Weight
Total weight
Whether the following standard
fittings are provided :
a. Rating and Technical plate
b. Earthing terminals with lugs2 nos.
c. 4 numbers flat , bi-directional
rollers
d. Lifting lugs
e. Off circuit tapping links
f.
Winding
temperature
indicator (Scanner type with
operating voltage of 240V)
g. HV termination- Cable end
box
h. LV termination – Cable end
box.
i. Whether 2 nos. potential free
contacts for high temperature
alarm and trip provided
j. Marshalling box fitted with
WTI Scanner (230 V AC)
k. Door limit switch
Outline
dimensions
of
the
transformers
a) Length (end to end )
b) Breadth (end to end)
c) Height
Note: Max overall dimension of the existing transformer is 2250 mm (W) including depth of
cable end box at both sides x 1650 mm (L) x 1950 mm (H) wherein the size of the tank is 1200
(W) x 1650 (L) x 1950 mm (H). LT cable end box 700 mm (W) x 1000 mm (L) x 825 mm (H)
from top of the tank. HT cable end box 300 mm (W) x 1000 mm (L) x 825 mm (H) from top of
the tank.
ANNEXURE-I
Item
No.
1
Description of item
Basic Price
(exclusive of all
levies &
charges)
Central
Excise
duty in
% only
VAT/
CST in
% only
Packing,
forwarding,
transit
insurance up
to site i/c
loading &
unloading
Other levies
(if any)
Unit price total
(all inclusive)
Supplying of 1000 KVA 3-phase 50
Hz self cooled (Air-Natural) Cast
resin, dry type, step down, double
wound copper, indoor distribution
transformer having Delta primary and
Star secondary designed for voltage
ratio of 6 KV/415Volt, between
phases at no-load, with Dyn11 vector
group connection having neutral
brought out on star side with matching
percentage impedance, voltage ratio
and vector group etc (details attached)
i/c provision for connecting cable on
HV & LT side, fitted with both side
cable end boxes and provided with
temperature protection devices and all
other standard fittings etc. as per
attached specifications complete.
Signature of Bidder with seal