What are the test items of dry type transformers?

The test items of dry type transformers are divided into conventional tests and special tests (also called type tests).

Routine tests are tests that must be done before each dry type transformer leaves the factory, which are:

1. DC resistance test

2. Power frequency withstand voltage test

3. Variable ratio test

4. Frequency doubling withstand voltage test (the so-called induction withstand voltage test)

5. No-load test

6. Load test

7. Insulation test

Type test is the test to be done for new type products, they are:

1. Lightning impulse test

2. Partial discharge test

3. Sudden short circuit test. .

Dry type transformers rely on air convection for cooling, and are generally used for local lighting and electronic circuits. Dry-type transformers are widely used in local lighting, high-rise buildings, airports, terminal CNC machinery and equipment, etc. Simply speaking, dry-type transformers refer to transformers whose iron cores and windings are not immersed in insulating oil. Cooling methods are divided into natural air cooling (AN) and forced air cooling (AF). Under natural air cooling, the transformer can run continuously for a long time under the rated capacity. When forced air cooling, the output capacity of the dry type transformer can be increased by 50%. It is suitable for intermittent overload operation or emergency accident overload operation; due to the large increase in load loss and impedance voltage during overload, it is in a non-economic operation state, so it should not be in continuous overload operation for a long time.