Explanation: All the transformers that are used in power system analysis have their secondary voltages equal to 11kV, 33kV, 66kV, etc. As this voltage ranges are commonly used in transmission lines, 122kV is the wrong option.

Explanation: One can increase the dielectric strength of oil, by changing the oil. Similarly, temperature rise and copper losses can also be controlled by using various techniques. The only thing which is constant is voltage ratio which can’t be altered.

Explanation: Voltage transformation ratio is equal to secondary induced emf to the primary induced emf. While the secondary and primary voltage induced are different from emfs as these are emf minus the losses in the line.

Explanation: Every electric device works in appropriate condition with maximum output and minimum losses when it is operated at rated conditions. Thus, if transformer is made to run at higher operating voltage its power factor will deteriorate.

Explanation: According to the primary and secondary equivalent circuits of a transformer equation stated in option 1 correctly suits with the kirchoff’s voltage law for primary side of a transformer, similarly equation for secondary side can also be written down.

Explanation: Approximate equivalent circuit of a transformer neglects the middle branch of transformer equivalent circuit’ which makes transformer circuit even more simpler. Then, all resistances (though they are negligible) are summed up as R and similarly all reactance as X.

Explanation: Hysteresis loss is directly proportional to frequency according to Steinmetz’s formula. While eddy current losses are directly proportional to square of flux density, thickness, frequency. Both losses are load independent.

Explanation: Hysteresis loss is directly proportional to voltage and frequency as well. It is load independent. Thus by doing voltage twice and frequency half of the original value we will get same hysteresis loss.