An induction motor can run at synchronous speed when____________?

A. stator resistance test
B. no-load test only
C. short-circuit test only
D. noue of the above

A. slip
B. rotor current
C. running torque
D. line voltage

A. single phase motors
B. variable speed motors
C. low horse power motors
D. high speed motors

A. open-circuit test only
B. short-circuit test only
C. stator resistance test
D. none of the above

A. directly proportional to slip
B. inversely proportional to slip
C. proportional to the square of the slip
D. none of the above

A. By changing the number of stator poles
B. Rotor rheostat control
C. By operating two motors in cascade
D. By injecting e.m.f. in the rotor circuit