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CGL W.O.T09935, Rev.1, Dt.05.05.11
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1.0 Transformer application / designation Auto Transformer
2.0 Applicable standards IS 2026
3.0 Quantity required 4 nos
4.0 Full load rating MVA 315
5.0 3 Phase unit / bank of three (3) 1 phase units 3phase unit
6.0Auto wound / two winding transformers / threewinding transformers
Auto Wound
7.0 Rated no-load voltages :
7.1 HV kV 400
7.2 IV kV 220
7.3 LV kV 33
8.0Cooling (ONAN / ONAF / OFAN / OFAF /
OFWF)ONAN/ONAF/OFAF
9.0 Ratings 189/252/315MVA
9.1 Ratings of windings
9.1.1 HV MVA 315MVA
9.1.2 IV MVA 315MVA
9.1.3 LV MVA 105MVA
9.2 Ratings corresponding to cooling methods
9.2.1 ONAN MVA 189
9.2.2 ONAF MVA 252
9.2.3 OFAF MVA 315
10.0
Guaranteed impedance voltage at rated current
for the principal tapping (indicate tolerance) at315 MVA
10.1 HV LV % 60%(+15% Tol)
10.2 HV IV %12.5%(+/-10% Tol) at principal
tap
10.3%(+/-15% Tol) at max. tap
15.4%(+/-15% Tol) at min. tap
10.3 IV LV % 45%(+15% Tol)
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10.4Zero Sequence impedance at principle tap
between HV & IV%
0.9-1.0 times of Positive seq.
impedance
11.0 Efficiency at 750C at unity p.f.
11.1 At full load % 99.84%
11.2 At full load % 99.86%
11.3 At full load. % 99.88%
Maximum efficiency will beachieved at a load of 140.87
MVA
12.0Regulation at full load, 0.8 P.F at 75
0C
winding temperature% 8.1%
12.1Regulation at full load, Unity P.F at 75
0C
winding temperature% 0.92%
13.0 Rated frequency Hz. 50
14.0 External short circuit withstand capacity MVAFault MVA :29000 ie3x420kVx40kA
for 3secs
15.0 Core :
15.1 Material of core laminationCold rolled grain oriented
silicon steel Grade M5
15.2 Thickness of core plates. 0.3mm (approx)
15.3 Insulation of core lamination. Karlite
15.4 Insulation of core bolts Fibre glass
15.5 Insulation of core bolt washers Fibre glass
15.6 Insulation of core clamping plates. Fibre glass
16.0 Winding connections :
16.1 HV Auto Star
16.2 IV Auto Star
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16.3 LV Delta
16.4 Vector group YNa0d11
17.0 Tappings on winding Taps on HV for HV variation
17.1 On-load / off taps On Load Tap changer
17.2 On HV / IV / LV winding HV
17.3 Full power tapping range + % +10% to -10%
18.0 If ON load taps, specify details of OLTC gear. Easun MR, India
18.1 Manual / automatic control Manual / automatic
18.2 Remote / local control Remote
18.3If remote control, whether the remote controlcubicle included in Bidders scope of supply
Yes
18.4 Voltage class of the OLTC 220 kV
18.5 Current rating of the OLTC A 802
19.0Terminals of tertiary (stabilising) winding
brought out to bushings
Yes /
NoYes
20.0 Winding insulation category : Class A
20.1 HV uniform / non-uniform Non-uniform
20.2 IV uniform / non-uniform Non-uniform
20.3 LV uniform / non-uniform Uniform
21.0 Type of axial coil supports
21.1 HVPermawood , Pressboardcylinders
21.2 IVPermawood , Pressboardcylinders
21.3 LVPermawood , Pressboard
cylinders
22.0 Type of radial coil supports
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22.1 HVPermawood , Pressboard
cylinders
22.2 IV Permawood , Pressboardcylinders
22.3 LVPermawood , Pressboardcylinders
23.0 Impulse voltage withstand 1.2 / 50 s wave
23.1 HV kV/Peak 1300kVp
23.2 IV kV/Peak 950kVp
23.3 LV kV/Peak 250kVp
24.0Power frequency withstand voltage (dry andwet)
24.1 HV; HV neutral kV(rms)
P.D measurement shall be
carried out with u=364 kV at200 Hz / 70 kVrms
24.2 IV kV(rms)Shall be carried out with PD
measurement
24.3 LV kV(rms) 95kVrms
25.0 Guaranteed maximum temperature rise
25.1 Oil by thermometers0C 50
25.2 Winding by resistance for :
25.2.1 ONAN cooling0C 55
25.2.2 ONAFCooling0C 55
25.2.3 OFAF Cooling0C 55
26.0
Switching impulse withstand voltage for
highest equipment voltage >145 kV. HV(400kV) 1050kVp
27.0 Tank cover conventional / bell shaped Bell shaped
28.0Minimum clearance height for lifting core and
windings from tankmm 8650
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29.0 Bushings HV/IV/LV/HVn
29.1 Rated voltage class kV 420 / 245 / 52 / 36
29.2 Rated current A 800 / 1250 / 3150 / 3150
29.3 1.2 / 50 s impulse withstand kV(p) 1425 / 1050 /250/170
29.4One minute power frequency withstand dry
and wetkV(rms) 630 /460/ 95/75
29.5 Minimum clearance in air(ph-ph/ph-gnd) mm
HV mm 4000/3500
IV mm 2350/2150
LV mm530/480 .. (Outdoor Air
clearances)
HV & IV neutral mm 320 . (Line to Earth)
29.6 Minimum creepage distance
29.6.1 Total mm
HV mm 13020
IV mm 7595
LV mm 1612
HV & IV neutral mm 1116
29.6.2 Protected mmApprox 50% of the total
protected creepage
29.7 Quantity of oil in oil filled bushings Litres HV Line : 200 ltr
IV Line : 50 ltr
LV Line : 5ltr;
LVN: Not Applicable
29.6.8Free space required at top for removal of HVBushing
mm 12500
30.0
Load loss at rated current and 315MVA at75
0C winding temperature between IV & HV
(guaranteed subject to tolerance as per
applicable standard and excluding coolerlosses)
430kW(Max) at 75deg C on
principal tap.
467kW(Max) at 75deg C onMaximum tap.
578kW(Max) at 75deg C on
Minimum tap.
31.0 Maximum cooler losses at full load kW 14kW(Max)
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32.0No load losses (core loss and di-electric loss) at100% rated voltage and frequency, guaranteedsubject to tolerance as per applicable standard
86kW(Max)
33.0 Guaranteed no-load current :
33.1When excited from LV side at 100% rated
voltageA
Approx 0.5% of the Full load
current
33.2When excited from LV side at 110% ratedvoltage
AApprox 1.5% of the Full loadcurrent
34.0 Maximum flux density
At 100% rated voltage Wb/m2 1.725
At 90% rated voltage Wb/m2 1.55
At 110% rated voltage Wb/m2 1.897
At 125% rated voltage Wb/m2 2.156
At 140% rated voltage Wb/m2 2.41
34.1 Overfluxing capability.
At 110% rated voltage Seconds Continuous
At 120% rated voltage Seconds 50
At 125% rated voltage Seconds 35
At 130% rated voltage Seconds 7
At 140% rated voltage Seconds 3
At 150% rated voltage Seconds 1
34.2 Voltage withstand time
At 110% rated voltage Seconds Continuous
At 120% rated voltage Seconds 50
At 125% rated voltage Seconds 35
At 130% rated voltage Seconds 7
At 140% rated voltage Seconds 3
At 150% rated voltage Seconds 1
35.0 Current density
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35.1 HV A/cm2 350(approx)
35.2 IV A/cm2 350(approx)
35.3 LV A/cm2 350(approx)
36.0 Wheels
36.1 Plain / flanged Flanged
36.2 Unidirectional / bi-directional Bi-directional
36.3 Quantity 8
36.4 Gauge (s) 1676
37.0 Vacuum withstand capability :
37.1 Main tankmm of
Hg.Full Vacuum
37.2 Radiators and accessoriesmm of
HgFull Vacuum
37.3 Pressure withstand capability :
37.4 Main tank torr Normal Head+5 PSI (35 kPa)
37.5 Radiators and accessories torr As per CBIP
38.0 All accessories supplied as specifiedYes /No
Yes
39.0Cooler control scheme conforms to
specification
Yes /
NoYes
40.0OLTC control scheme conforms tospecification
Yes
41.0 Weights
41.1 Net weight of the core kg 70500 approx.
41.2 Net weight of copper
41.2.1 HV kg24700 approx. (Series + Tapwinding)
41.2.2 LV kg12500 approx. (Common
winding)
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41.2.3 Tertiary kg 3600 approx.
41.2.4 Total kg 40800 approx.
41.3 Oil kg 77000 approx
41.4 Tank, coolers and fittings kg 77000 approx
41.5 Total Weight of transformer kg 314000 approx
41.6 Untanking weight kg 157000 approx
42.0 Sheet metal thickness
42.1 Outdoor cooler control cabinet mm 2.5 mm (approx)
42.2 Indoor OLTC control cabinet mm 2.5 mm (approx)
43.0Cooling fans : (State separately for ONAF &OFAF)
43.1 Type Propeller type
43.2 Quantity No.8 nos. working + 2 nos.Standby = 10 nos. total
43.3 Rating kW 0.7 kW per fan
44.0 Cooling oil pumps44.1 Type Axial flow
44.2 Quantity No. 2 running + 2 standby
44.3 Rating kW 4.1 kW per pump
45.0 Cooling water pumps NA
45.1 Type NA
45.2 Quantity No. NA
45.3 Rating kW NA
46.0
Capability of transformer to remain in
operation from hot condition after failure of
forced cooling
46.1 Full load Minutes 10 minutes (approx)
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47.0 On-load tap changer
47.1 Make Easun MR ,India
47.2 Type designation 3 x MI
47.3 Suitable for auto / manual operation Auto /manual
47.4 Rated voltage kV 245kV
47.5 Rated current Amp 800A
47.6 Number of steps 16
47.7 Step voltage Volts 1.25%
47.8 Rated voltage of drive motor V 400
47.9 Rated voltage of control circuit V 400
47.10Time to complete tap changing operation fromany one step to next higher or lower step
47.10.1 On auto operation Sec. 5secs (approx)
47.10.2On Manual operation i.e., through pushbutton
Sec. 5secs (approx)
48.0 List of routine tests to be carried out As per IS2026/ CBIP
49.0 Winding resistance, per phase at 75 deg.C
49.1 HV (from HV Line to Neutral) ohm 0.6867 approx.
49.2 IV (from IV Line to Neutral) ohm 0.4095approx.
49.3 LV ohm 0.12 approx.
50.0 Conductor area
50.1 Series winding sq.mm 250 approx.
50.2 Common winding sq.mm 150 approx.
50.3 Tap winding sq.mm 145 approx.
50.4 LV winding sq.mm 303 approx.
50.5Inter turn insulation for LV,TAP, Common &
Series windingInsulating Kraft Paper
50.6 Inter winding insulation Pre-compressed press boards
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50.7 LV winding to Core insulation Pre-compressed press boards
51.0 Shipping section
51.1 Size of largest package (LxBxH) mm16300 x 10450 x 10500
approx.
51.2 Weight of the largest package Tonnes 236 approx
52.0Manufacturers maintenance procedure andschedule for spare uncharged transformer
After final testing
53.0 Overload capacity of transformer for with allfans working simultaneously.
As per IS 2026
54.0 Bushings CTs, if offered
54.1 Quantity
54.2 Ratio
54.3 VA burden
54.4 Accuracy class Refer Table below
54.5 Knee point voltage Volts
54.6 Magnetising current at knee-point voltage Amps
54.7 Secondary resistance Ohms
55.0Values of transfer surge voltage withstand on
LV :
55.1 Lightning surges
55.1.1 Amplitude kVp
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arrangement is used.
58.0Whether neutral end surge diverter
recommended by the BidderNot required.
59.0 If yes, details of surge diverter NA
59.1 Make NA
59.2 Type NA
59.3 kV class NA
59.4 kV rating NA
60.0If unit cooler arrangement offered for cooling,advise ?
Pressed Steel sheet Radiators of
Unpainted Hot dippedGalvanised are used
(520 Wide x 1.2 mm thk)
60.1 Total no. of unit coolers provided.Radiators are arranged in 2
Banks of 50% capacity each.
60.2No. of unit coolers which would be in servicefor full load operation of transformer.
2 x 9 nos. per bank = 18 nos.total
60.3 No. of spare unit coolers NA
60.4 No. of fans in each unit cooler nos2 x (4 nos. working + 1 no.standby) per bankTotal 10 Nos.
60.5 No. of pumps in each unit cooler
2 x (1no. working + 1nos.
standby) per bankTotal 4 nos.
60.6 Rating of each fan motor3-Phase, 400V, 50Hz, 0.5A,
700Watts
60.7 Rating of each oil pump motor4500LPM, 3-Phase, 415V
10%, 50Hz, 8A, 4.1kW
61.0 Quantity of paper used for insulation kg 1700 approx.
62.0 Quantity of copper used for each winding kg Specified in Cl. 41.2 above
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Rev.01- Customer comments dated 4/05/11 are incorporated T1D/AVD-SS 05/05/11