Why is indirect testing of transformers necessary?

Open circuit & Short circuit test is also known as the Indirect Test. Performance of a transformer can be determine without any actual loading at any load and power factor by open and short circuit test. This test are very economical because power require is very less to perform this test.

Why large power transformer testing under full load current is not possible?

Statement (I): A large power transformer in loaded condition carries large amount of current and voltages. So, it’s very difficult to arrange such high rating voltmeter, ammeter and wattmeter. Therefore, the testing under full load current is not possible.

What are the main difficulties encountered in testing of large transformers by direct loading?

Some of the difficulties encountered in testing large transformers are: For carrying out tests for large transformer huge amount of energy is wasted. For carrying out direct tests by loading the transformer large amount of load is to be available at the test center.

Why testing of transformers is important before its use in any application?

The purpose of this test is to check for differences in resistance between windings and opens in the connections. This test ensures that each circuit is properly wired properly and that all connections are tight. Resistance testing is performed using a transformer ohmmeter.

What is the main cause of noise in the transformer?

The main cause of transformer noise is the Magnetostriction Effect. The alternation current that flows through an electrical transformer’s coils has a magnetic effect on its iron core. It causes the core to expand and contract, resulting in a humming sound.

Why direct loading method is not used for large alternators?

Alternators at the power plants are of large rating as 500MVA. It is difficult to determine voltage regulation for such high capacity alternators using direct loading at the laboratory. It is therefore to perform indirect methods by indirectly simulating the load conditions which consumes less power.