Question about Transformer

Hi,
Why we use low voltage side for no load test and use high voltage side for short circuit test.
thanks

panda1234 said:

Hi,
Why we use low voltage side for no load test

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Since the secondary of the transformer is open, the primary draws only no-load current, which will have some copper loss. This no-load current is very small and because the copper loss in the primary is proportional to the square of this current, it is negligible. There is no copper loss in the secondary because there is no secondary current.

panda1234 said:

Hi,
Why we use high voltage side for short circuit test

Click to expand...

The supply voltage required to circulate rated current through the transformer is usually very small and is of the order of a few percent of the nominal voltage and this 5% voltage is applied across primary. The core losses are very small because applied voltage is only a few percentage of the nominal voltage and hence can be neglected. Thus the wattmeter reading measures only the full load copper loss.