Exciters of synchronous machines are

The maximum power developed in a synchronous motor occurs at a coupling angle of

A. 30°

B. 60°

C. 90°

D. 180°

When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor

A. remains same as the original value

B. decreases to half the original value

C. tends to becomes zero

D. increases to two times the original value

The speed of a synchronous motor

A. increases as the load increases

B. decreases as the load decreases

C. always remains constant

D. none of the above

In which of the following motors the stator and rotor magnetic field rotate at the same speed ?

A. Universal motor

B. Synchronous motor

C. Induction motor

D. Reluctance motor