POWER TRANSFORMER 1 Insulation Resistance Measurement Procedure a. For LT systems, use only 500V or 1000V Megger. b. For MV & HV systems, use 2500V or 5000V Megger. c. Remove Earth from Transformer neutral. d. Measure as per table below. Circuit Megger Use MV & HV 1U - E 5kV 2U - E 5kV 1U - 2U 5kV 2 Winding Resistance Measurement Circuit Tap No Resistance Ω 1U-1N All Taps 1V-1N 1W-1N 2U-2N 2V-2N 2W-2N 1U 1V 1W 1N 2U 2V 2W 2N 1U 1V 1W 1N 2U 2V 2W 2N WINDING RESISTANCE METER I I I I I1 P1 P2 I2
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POWER TRANSFORMER
1 Insulation Resistance MeasurementProcedurea. For LT systems, use only 500V or 1000V Megger.b. For MV & HV systems, use 2500V or 5000V Megger.c. Remove Earth from Transformer neutral.d. Measure as per table below.
Circuit Megger UsedMV & HV
1U - E 5kV2U - E 5kV1U - 2U 5kV
2 Winding Resistance Measurement
Circuit Tap No Resistance Ω
1U-1N All Taps1V-1N1W-1N
2U-2N2V-2N2W-2N
1U
1V
1W
1N
2U
2V
2W
2N
1U 1V 1W 1N
2U 2V 2W 2N
WINDING RESISTANCE METERI I I I
I1 P1 P2 I2
3 Magnetic Current Test
Applied Voltage Measured Current1U-1V 1U1V-1W 1V1W-1U 1W1U-1N, 1V-1N,1W-1N 1N