Transformer Interview Questions & Answers Part-2

What is the formula of transformer voltage regulation?

A transformer has 300 turns on the primary, 100 turns on the secondary, and 120VAC applied to the primary, what is the voltage across the secondary?

V2=40 Volts

The same transformed can be used as step up or step down transformer. It all depends on which side voltage is being applied. It is very easy to identify the transformer for step up or step down operation.

Measure the resistance of primary and secondary winding of the transformer.

The high voltage winding has more resistance because there is more number of turns of thinner cross section area wire.

The low voltage winding has low resistance because there is less number of turns of thicker cross section area wire.

Now we can use this transformer as a step or step down operation.

When transformer is on load, the system power factor can be improved to the some extent by lowering the voltage through OLTC. The decreased voltage reduce the reactive power, and thus power factor gets improved