5.

0 MVA Inverter Duty Transformer

Sl. No. Particulars Unit Technical Particulars Data to be filled by bidder Remarks
1 Make
2 Type- Suitable for Outdoor continuous service Outdoor continuous service
3 Number of windings per phase, CCA 3 phase, 3 windings, CCA-1
4 Reference Standard IS 2026 , IEC 60076
5 Rating 5.0 MVA (Each Winding 2.5MVA)
6 Type of Cooling ONAN
7 Rated output (MVA) With ONAN Cooling 5.0 MVA
8 Rated Voltage (KV)
8.1 HV 11 kV
8.2 LV 2 x 0.8 kV
9 Volatage & Frequency variation ± 10% & ± 5%
10 Rated Current (A)
10.1 HV 400
10.2 LV 3000 (Each)
11 Thermal Withstand Capability 2 sec
12 Rated Frequency (Hz) 50
13 Vector Group after 3 phase connection YNd11d11
14 Voltage Withstand Time
14.1 110% of rated voltage Continuous
14.2 125% of rated voltage 1 Minute
14.3 140% of rated voltage 5seconds
15 Overfluxing Capability
15.1 For Overfluxing Factor 1.10 Continuous
15.2 For Overfluxing Factor 1.25 1 Minute
15.3 For Overfluxing Factor 1.40 5 Second
16 Reference(Ambient Temperature) 50 Deg C
16.1 Temperature rise over reference ambient Deg. C 45 Deg C
16.2 (i).Of top oil by thermometer at 100% loading 50 Deg C
(ii). Of top oil by thermometer at 110% loading 50 Deg C
16.3 (i) Of winding by resistance at 100% loading 55 Deg C
110% continuous overloading,
(ii) Of winding by resistance at 110% loading without increase of designed
hotspot temperature i.e. 98 Deg C
Maximum continuous over loading capacity of
17 transformer without exceeding the specified winding
temperature Yes
17.1 Tapping - Taps furnishedon HV winding
17.2 Type Off Circuit Tap Switch
17.3 Capacity To be furnished by the Bidder
+5.0% to -5.0% in steps of 2.5%, 4
17.4 Range- Steps X % Variation
steps & 5 position.
Impedances at Principal Tap at Rated Frequency and 75°
18 7% ( with +/- IEC tolerance)
C winding temperature
18.1 Impedances at Lowest Tap To be furnished by the Bidder
18.2 Impedances at Highest Tap To be furnished by the Bidder
Tolerance for impedance ±1% between all single phase
18.3 Tolerance as per IEC 60076
units
19 Resistance of HV & LV winding To be furnished by the Bidder
20 Zero sequence impedance of HV &LV winding To be furnished by the Bidder
21 Basic insulation level – HV winding
21.1 One minute power frequency withstand voltage 28 kVrms
21.2 Lightning impulse withstand voltage 75 kVPeak
22 Basic insulation level –LV winding
22.1 One minute power frequency withstand voltage 10 kVrms
22.2 Lightning impulse withstand voltage 40 kVPeak
23 Basic insulation level – HV neutral
23.1 One minute power frequency withstand voltage 28 kVrms
23.2 Lightning impulse withstand voltage 75 kVPeak
24 Basic insulation level – Shield Bushing
24.1 One minute power frequency withstand voltage To be furnished by the Bidder
24.2 Lightning impulse withstand voltage To be furnished by the Bidder
25 HV bushing make & type To be furnished by the Bidder
25.1 HV bushing rated current in Amp To be furnished by the Bidder
25.2 Rated thermal short time current
25.3 HV bushing rated voltage 12 kV
HV bushing 1 minute power frequency withstand
25.4 28 kVrms
voltage
25.5 HV bushing lightning impulse withstand voltage 75 kVPeak
25.6 HV bushing minimum creepage distance in mm 25 mm/kV
25.7 HV bushing maximum tan delta value To be furnished by the Bidder
25.8 Minimum withstand value of cantilever load on bushing As per IEC 60137
26 LV bushing make & type
26.1 LV bushing rated current To be furnished by the Bidder
26.2 Rated thermal short time current To be furnished by the Bidder
26.3 LV bushing rated voltage 3.6kV
26.4 LV bushing 1 minute power frequency withstand voltage 3kVrms
26.5 LV bushing lightning impulse withstand voltage 10 kVPeak
 5.0 MVA Inverter Duty Transformer
Sl. No. Particulars Unit Technical Particulars Data to be filled by bidder Remarks
26.6 LV bushing minimum creepage distance in mm 25mm/kV
26.7 LV bushing maximum tan delta value To be furnished by the Bidder
26.8 Minimum withstand value of cantilever load on bushing As per IEC 60137
27 HV Neutral bushing make & type To be furnished by the Bidder
27.1 HV neutral bushing rated current
27.2 HV neutral bushing rated voltage 12kV
HV neutral bushing 1 minute power frequency
27.3 28 kVrms
withstand voltage
27.4 HV neutral bushing lightning impulse withstand voltage 70 kVPeak

27.5 HV neutral bushing minimum creepage distance in mm 25mm/kV

27.6 HV Neutral bushing maximum tan delta value To be furnished by the Bidder
28 Shield bushing make & type To be furnished by the Bidder
28.1 Shield bushing rated current To be furnished by the Bidder
28.2 Shield bushing rated voltage 3.6 kV
Shield bushing 1 minute power frequency withstand
28.3 10 kV rms
voltage
28.4 Shield bushing lightning impulse withstand voltage 40 kVPeak
28.5 Shield bushing minimum creepage distance in mm 25mm/kV
28.6 Shield bushing maximum tan delta value To be furnished by the Bidder
29 LV Differential CT Details:
29.1 Ratio To be Confirm by the Bidder
29.2 Knee point voltage Vk & accuracy Class
29.3 CT Resistance in ohm As per CBIP + 15 mm
30 HV terminal clearance phase to phase As per CBIP + 15 mm
31 HV terminal clearance phase to earth 280 mm ( min)
32 LV terminal clearance phase to phase 150 mm
2 A / mm^2 @ rated tap for
33 LV terminal clearance phase to earth Aluminium winding & 3.5 A/mm^2
for copper flat & bushing leads.
34 Maximum current density (Amp / sqmm)
35 Transformer Losses:
Transformer no load loss at rated voltage, frequency & 0.1% (Max. allowed without any
35.1
at 75°C positive tolerance)
Transformer load loss at rated current, voltage, 1% (Max. allowed without any
35.2
frequency & at 75°C positive tolerance)
35.3 Transformer stray loss @ 75 deg C To be furnished by the Bidder
35.4 Transformer auxiliary loss at rated load To be furnished by the Bidder
35.5 Total losses (max.) To be furnished by the Bidder
0
36 Efficiency at 100% rated load, 75 C and 0.9 power factor To be furnished by the Bidder

37 Maximum efficiency To be furnished by the Bidder

37.1 Load & power factor at which it occurs
38 Marshalling box
38.1 Enclosure ingress protection class IP 55
38.2 Panel sheet thickness To be furnished by the Bidder
38.3 Weight of MB panel To be furnished by the Bidder
38.4 Tank – conventional type Conventional Type
38.5 Thickness of steel plate used To be furnished by the Bidder
Tank design tested as per relevant IS / IEC / CBIP for
38.6 As per CBIP Guidelines
Vacuum & Pressure test
39 Core material grade – M4 or better
39.1 Thickness of lamination <=0.27mm
39.2 Total no of steps To be furnished by the Bidder
Design flux density in the core at rated condition at
39.3 To be furnished by the Bidder
principal tap
Guaranteed No Load current at 100% rated voltage on
39.4 To be furnished by the Bidder
HV & LV side
39.5 No of Core Limbs
39.6 Total Stack Thickness
39.7 Gross area of Core
39.8 Core stacking Factor
To be furnished by the Bidder
39.9 Core Circle diameter
39.10 Height of Window
39.11 Width of Window
39.12 Center to Center distance between limbs
39.13 Source of Core Material
40 Type of Winding – HV & LV Side To be furnished by Bidder
40.1 Conductor material – Cu or Al High Grade Electrolytic Aluminium
40.2 Conductor cross section-HV & LV Side To be furnished by the Bidder
40.3 Insulating material To be furnished by the Bidder
40.4 Insulating material thickness HV Turn & LV Turn To be furnished by the Bidder
40.5 Voltage per turn
2 A / mm^2 @ rated tap for
40.6 Current density Aluminium winding & 3.5 A/mm^2
for copper flat & bushing leads.
40.7 Mean Diameter
 5.0 MVA Inverter Duty Transformer
Sl. No. Particulars Unit Technical Particulars Data to be filled by bidder Remarks
40.8 Number of turns / phase
To be furnished by the Bidder
40.9 Length of mean turn
40.10 Source of receipt of copper
41 Insulating oil as per specification As per IEC 60296 / IS 335
41.1 Quantity of oil in main tank To be furnished by the Bidder
41.2 Quantity of oil in conservator To be furnished by the Bidder
42 Total quantity of oil To be furnished by the Bidder
43 5% excess oil furnished? Yes/No
44 Winding Current Transformer (WCT) To be furnished by the Bidder
44.1 Type & make To be furnished by the Bidder
44.2 Reference Standard To be furnished by the Bidder
44.3 CT Ratio To be furnished by the Bidder
44.4 Burden, VA To be furnished by the Bidder
44.5 Class of Accuracy To be furnished by the Bidder
45 Pressure release device- PRV make To be furnished by the Bidder
45.1 Minimum pressure the device is set to rupture To be furnished by the Bidder
46 Buchholz Relay make To be furnished by the Bidder
47 Sudden Pressure Relay make To be furnished by the Bidder
48 OTI make To be furnished by the Bidder
49 WTI make To be furnished by the Bidder
50 Magnetic Oil level Gauge make To be furnished by the Bidder
Fittings Accessories as given in specification (Bidder shall
51 attach separate sheet giving details, make and bill of To be furnished by the Bidder
materials)
Painting for external surface – shade & thickness in
52
micron RAL 7032& minimum dry film
Painting for internal surface – shade & thickness in thickness shall ber 100 microns
53
micron
Transformer overall dimensions Length x Width x Height
54 To be furnished by the Bidder
( mm)
Transformer MB/CCC panel dimensions Length x Width
55 To be furnished by the Bidder
x Height (mm)
56 Transformer total weight To be furnished by the Bidder
56.1 Tank weight To be furnished by the Bidder
56.2 Core weight To be furnished by the Bidder
56.3 Winding weight To be furnished by the Bidder
56.4 Frame parts weight To be furnished by the Bidder
56.5 Total weight of oil To be furnished by the Bidder
56.6 Largest consignment transport weight To be furnished by the Bidder
56.7 Total Weight of transformer with 1st filling oil To be confirmed by the Bidder
All in process tests confirmed as per specification /
57 To be confirmed by the Bidder
quality plan?
Performing all Type Tests as per specification included in
58 To be confirmed by the Bidder
offer?
Performing all Routine Tests as per specification
59 To be confirmed by the Bidder
included in offer?
60 All Special Tests confirmed as per specification? To be confirmed by the Bidder
61 All documents submitted as per specification? To be furnished by the Bidder
Reference list of clients for supply of similar rating of
62 To be furnished by the Bidder
transformer enclosed?
Deviation sheet submitted with reference to
63 To be confirmed by the Bidder
specification clause?
1) 20% spare radiators to be considered in radiator
bank.
64 2) LV1 & LV-2 on one side and LV3 & LV4 on the other To be confirmed by the Bidder
side at 180deg from each other. HV cable box shall be
90deg from LV Cable box

General Description
Bidder to confirm that offer transformer shall be type tested design of similar rating. If Bidder does not have valid type test report then type test & short circuit test shall
1
carry out by bidder without any price implication.A transformer is considered similar to another transformer inline with IEC 60076.
2 Transformer overloading @110% without increase in hotspot temperature of 98Deg C at weighted ambient of 32 Deg C. Bidder to confirm.
3 Transformer Hotspot temperature 98deg@weighted ambient temperature of 32degC. Bidder to confirm
The maximum flux density in any part of the core & yoke at the rated MVA, voltage & frequency shall be such that under 110% continuous voltage condition it does not
4
exceed 1.9 tesla.
Bidder to carry out Type test i.e Temp. rise test & Lightning impulse test and special test i.e Zero sequence impedance, measurement of harmonics of no load current and
5
acoustic noise level in one of the transformer for design validation.
6 Sub-vendor proposed by bidder is subjected to approval of Purchaser QA team.
7 Bidder to confirm that clearance between Ph-Ph & Ph-E for HV Side and LV side shall be provided as per specification