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Transformer oil withstand voltage test operation precautions

Know the site before the test, know the location of the electrified body, and take safety measures.

Clear safety distance between workers and live equipment: below 10KV - 0.7m35KV - 1.0m110KV - 1.5m220KV - 3.0m500KV - 5.0m

Generally, the transformer oil to be tested is more than 1cm-1.5cm in the tester. If there is less, the measured data will have errors. For example, the transformer oil may be sputtered during the test. !

When the test data appears in the obvious error of other data, since the new sample is taken from the new test, the magnetic shaft may not be able to rotate due to the failure of the bipolar during operation, and at this time, due to the C element in the oil Carbonization leads to a small amount of carbon in the oil, which may lead to errors in the test (recommended manual mixing).

The experiment is generally done 5 to 6 times, eliminating the cause of the error and averaging to determine the result.


Draw the oil sample for a standing time: 35KV and below - 24 hours;

110KV~220KV - 48 hours;

500KV and above - 72 hours;

The Max. Value of test breakdown voltage: 35KV - 35KV; 110KV ~ 220KV - 40KV; 330KV and above - 60KV;

Each test requires stirring for 60 s and allowed to stand for 5 min.

DC transformer current measurement requirements for power transformer windings and bushings.

When the transformer voltage level is 35kV and above, and the capacity is 10000kVA and above, the DC leakage current should be measured;

The test voltage standard shall comply with the following table. When the test voltage was applied for 1 min, the leakage current was read at the high voltage end.


1 When the rated voltage of the winding is 13.8kV and 15.75kV, it is based on the standard of 10kV; at 18kV, it is based on the standard of 20kV.

2 The graded insulation transformer is still based on the voltage level of the tested winding.

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