Product parameters
△ Rated capacity: 50000/25000~25000kVA;
△ Rated voltage: 15.75/10.5~10.5kV;
△ Rated current: 1833/1375~1375A;
△ Rated frequency: 50Hz;
△ Number of phases: 3 phases;
△ Tap range: 15.75±2x25%/10.5~10.5KV;△ Connection group number: Dd0;
△ Cooling method: ONAN/ONAF:
△ Insulation heat resistance grade: A;
△ Insulation level: LI125 AC55/LI105 AC45-LI105 AC45.
Test items and results
Insulation resistance, absorption ratio and dielectric loss measurement t=33℃
Absorption ratio | Dielectric loss measurement (%) | Insulation resistance(mΩ) |
H.V. - L.V. and ground | 1.36 | H.V. - L.V. and ground | 0.48 | H.V. - L.V. and ground | 2500 |
L.V. - H.V. and ground | 1.42 | L.V. - H.V. and ground | 0.43 | L.V. - H.V. and ground | 2500 |
H.V. and L.V. - ground | 1.39 | H.V. and L.V. - ground | 0.46 | H.V. and L.V. - ground | 2500 |
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| Core-ground | 650 |
Voltage ratio measurement and connection number verification
H. V. Winding | L. V. Winding | Transformation ratio K | Voltage ratio deviation % | Link Group |
Tap voltage | Voltage(kV) | Voltage(kV) | AB/ab (right side/left side) | BC/bc (right side/left side) | CA/ca (right side/left side) |
1 | 16.54 |
| 1.575 | -0.20/-0.17 | -0.20/-0.17 | -0.20/-0.17 |
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2 | 16.145 |
| 1.538 | -0.09/-0.05 | -0.09/-0.05 | -0.09/-0.05 |
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3 | 15.75 | 10.5 | 1.5 | 0.05/0.01 | 0.05/0.01 | 0.05/0.01 | D, d0-d0 |
4 | 15.355 |
| 1.462 | 0.16/0.18 | 0.16/0.18 | 0.16/0.18 |
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5 | 14.96 |
| 1.425 | 0.27/0.27 | 0.27/0.27 | 0.27/0.27 |
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Winding resistance measurement t=33℃
High voltage winding phase order | AB | AC | BC | Unbalance rate% |
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1 | 0.01452 | 0.01452 | 0.01456 | 0.3 |
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2 | 0.01434 | 0.01430 | 0.01423 | 0.8 |
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3 | 0.01389 | 0.01394 | 0.01392 | 0.4 |
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4 | 0.01354 | 0.01361 | 0.01360 | 0.5 |
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5 | 0.01317 | 0.01321 | 0.01321 | 0.3 |
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L. V. Winding | ab (right side/left side) | bc (right side/left side) | ac (right side/left side) | Unbalance rate % |
0.009459/0.009302 | 0.009448/0.009337 | 0.00948/0.009264 | 0.1/0.8 |
Externally applied pressure test
Pressure point | Test voltage(kV) | Test time(S) | Results |
H.V. - Ground and L.V. | 55 | 60 | Passed |
L. V. - Ground and H.V. | 45 | 60 |
Induction withstand voltage test
Applied voltage(kV) | Induced voltage(kV) | Induction multiple % | Frequency test(Hz) | Test time(S) | Results |
L.V. | H.V. |
21 | 31.5 | 200 | 200 | 30 | Passed |
No-load current and no-load loss measurement
Average voltage (kV) | Effective value voltage (kV) | No-load current | No-load loss(kW) |
(A) | % | Measured value | Correction value |
10.484 | 10.513 | 57.3 | 0.41 | 29.835 | 29.727 |
Short circuit impedance and load loss measurement t=75℃
Operation mode | Impedance voltage (%) | Load loss (kW) |
High pressure-(low pressure 1- low pressure 2) | 11.1 | 187.05 |
High pressure-low pressure 1 | 17.8 | 74.309 |
High pressure-low pressure 2 | 21.1 | 79.975 |
Low pressure 1- low pressure 2 | 39.5 | 22.137 |
△ Transformer oil test
Oil No. 25 # Dielectric strength 40 kV
△ Partial discharge test
Under 1.5 times the maximum phase voltage: 85PC
△ Noise level test distance
2m from the transformer body: 61dB
Sealing test
Test methods | Applied pressure (k Pa) | Test time(h) | Residual pressure(%) | Results |
Static air pressure method | 20 | 24 | 70 |
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