Which of the following motors is non-self starting ?
(A) D.C. series motor
(B) synchronous motor
(C) Squirrel cage induction motor
(D) Wound round induction motor
The magnitude of field flux in a 3-phase synchronous motor?
(A) varies with power factor
(B) varies with speed
(C) varies with the load
(D) remains constant at all loads
The ratio of starting torque to running torque in a synchronous motor is____________?
(A) zero
(B) one
(C) two
(D) infinity
The induced e.m.f. in a synchronous motor working on leading power factor will be_____________?
(A) more than the supply voltage
(B) less than the supply voltage
(C) equal to the supply voltage
(D) None of these
When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop_________________?
(A) inductor motor torque
(B) induction generator torque
(C) synchronous motor torque
(D) d.c. motor toque
(D) none of the above
While starting a synchronous motor by induction motor action, field winding is usually_____________?
(A) connected to D.C. supply
(B) short-circuited by low resistance
(C) kept open-circuited
(D) none of the above
Armature of a synchronous machine is____________?
(A) of reducing number of slip rings on the rotor
(B) armature is associated with large power as compared to the field circuits
(C) of difficulty of providing high voltage insulation on rotor
(D) all of the above reasons
The power factor of a synchronous motor is better than that of induction motor because
(A) stator supply is relieved of responsibility of producing magnetic field
(B) mechanical load on the motor can be adjusted
(C) synchronous motor runs at synchronous speed
(D) synchronous motor has large air gap
If one-phase of a 3-phase synchronous motor is short-circuited, motor will ______________?
(A) will refuse to start
(B) will overheat in spots
(C) will not come upto speed
(D) will fail to pull into step
The maximum speed variation in a 3-phase synchronous motor is____________?
(A) 10 per cent
(B) 6 per cent
(C) 4 per cent
(D) 2. per cent
(D) zero