Q.Why star point of star connected motor is not grounded?
Ans:-

Normally the 3 phase induction motors are not star connected. In the star connected machine the phase voltage will be 1/ 3 times. So that the torque of the machine will be reduced. Because of this reason normally all the induction motors are having delta connected field windings.

Q.If we put field winding on stator and armature winding on rotor then how will it operate? Will it rotate at synchronous speed or not? (Assuming that the alternator is feasible?
Ans:-
Yes, It would surely operate and run at synchronous speed. But it would be uneconomical because we should have 3 slip rings of very high current handling capacity and because of this efficiency will decrease and we will require to have high level of insulation ...

Q.Motor manipulator detail is 230v 50hz frequency. If you increase frequency what will happen?Is there any need for coil protection?

Ans:-
Latest Answer: Speed N=120f/p so if we increase the frequency the seed will also increase as per our electrical stands in India we are maintaining 50Hz as the constant frequency it is better maintaining the frequency. Definitely there will be a damage for coil ...

Q.What is Dark lamp method?
Ans:-
this is the method used while installing new generator in synchronism with the exixting generation station. the bulb glows or get off with the phase sequence of generator n d rate of glowing n switching off depends upon d frequencyof d same

Q.why ohms law is nt applicable on transformers?
Ans:-Ohms law is applicable to circuits that have constant resistance, ie linear circuits.

Transformers have inductive coils that make the resistance varying with the number of turns on primary and secondary coils, so Ohms law in not applicable there.

However, you can apply ohms law to primary and secondary circuits separately.

Q.What is Over excitation?
ans:-

when reactive power inserted > required then we say dat excitation is over

Q. What is meant by Crawling in Induction motors?
ans:-
the stabled rotation of induction motor at a speed N/7 due to 7th harmonic component

Q. What are V and inverted V curves?

ans:-
v curve : it is the curve drawn between arm curr and field current in a syn motor

inv v curve : it is the curve drawn between power factor and field current in a syn motor