01․ The primary and secondary windings of a transformer are

Whenever alternating voltage is applied to the primary of a electrical transformer, there will be a alternating flux through the core of transformer. As this flux will link with secondary winding there will be an induced emf in the secondary winding. The phenomenon of inducing voltage by changing flux is called electrical induction, hence it can be concluded that the windings of a transformer are linked inductively.

02․ At what power factor, the voltage regulation of a transformer can be zero ?

03․ In a three phase star - delta transformer, what is the angle difference between primary and secondary phase voltages?

This is a vector group and has + 30° displacement. Therefore, delta side leads by + 30°.

04․ What will be the eddy current loss if the supply frequency of a transformer becomes double?

Eddy Current loss in transformer is denoted as,
Where, K

_{e}= eddy current constant, K_{f}= form factor. Hence apparently, the eddy current loss P_{e}∝ f^{2}, but for any given voltage, if f decreases, B_{m}increases correspondingly and if f increases B_{m}decreases correspondingly. Hence the eddy current loss P_{e}at any given voltage, is independent of frequency.05․ The efficiency of a transformer is mainly dependent on

Iron loss is caused by the alternating flux in the core and consists of hysteresis and eddy current losses. These losses occur in the core and yoke due to alternating flux.
Copper losses occur in the primary and secondary windings due to their resistances when the transformer is loaded.
Iron losses ( core losses ) are independent of load, and therefore are called constant losses. Generally at maximum efficiency the core loss of transformer is equal to copper loss. Again the transformers are so designed that maximum efficiency of transformer reaches at full load current. So for all other load copper loss is less than core loss hence core loss dose have maximum value among all other losses in a power transformer and that is why the efficiency of a transformer mainly depends upon core losses.

06․ If supply frequency of a transformer decreases,