When testing the direct resistance of the transformer, select the direct resistance model according to the transformer capacity:
①.The transformer below 10MVA selects 5A direct resistance.
②.10A direct resistance is selected for transformers from 10MVA to 63MVA.
③. Transformers from 63MVA to 120MVA select 20A direct resistance or three-channel 10A direct resistance
④. Transformers from 120MVA to 240MVA select 40A, 50A direct resistance or three-channel 20A direct resistance
⑤. For transformers larger than 240MVA, choose 40A, 50A or three-phase 20A direct resistance, 100A direct resistance
Note: The magnitude of the current of the DC resistance tester is not strictly related to the measurement accuracy, and the test time for measuring large-capacity transformers with a low-current DC resistance tester will be slower.