ISRO Scientist or Engineer Electrical 2013

which is the same as the steady-state magnetizing current

which is several times the steady-state magnetizing current, depending upon the initial state of the residual flux in the transformer core.

which is several times the steady-state magnetizing current, independent of the initial state of the residual flux in the transformer core.

which is twice the steady-state magnetizing current provided the core has no residual flux.

the voltage and current are both in phase

the voltage and current both differ in phase by $$30^\circ$$

the voltage differ in phase by $$30^\circ$$ but currents are in phase

the current differ in phase by $$30^\circ$$ butvoltages are in phase.

$$N, \frac{2}{\surd{3} N}$$

$$\frac{N}{2}, N$$

$$\frac{\surd{3} N}{2}, N$$

$$N, \frac{\surd{3} N}{2}$$

decreases the total weight / kVA

increases the total weight / kVA

decreases the weightof iron / kVA but increasesthat of copper

decreases the weight of copper / kVA but increases that of iron

three times

1.5 times

0.5 times

will remain the same

Copper loss

Hysterisis loss

Core loss

Eddy current loss.

More than full load copper loss

Equal to full load copper loss

Less than full load copper loss

Negligible compared to full load copper loss

SC test.

OC test.

Half time on SC and half time on OC.

Sumpner’s test.

Improve line frequency.

Compensate inductive reactance.

Compensate capacitive reactance

Balance harmonics.

Adding external resistance to rotor

Adding external inductance to rotor

Adding external capacitance to rotor

Adding external RLC circuit to rotor