Synchronous Motor mcq objective questions and answers part1

Q1. The speed regulation of a synchronous motor is always
(A) 0.01
(B) 0.5
(C) positive
(D) zero

Q2. The shaft of synchronous motor is made of
(A) mild steel
(B) chrome steel
(C) alnico
(D) brass

Q3. The oscillations in a synchronous motor can be damped out by
(A) maintaining constant excitation
(B) running the motor on leading power factors
(C) providing damper bars in the rotor pole faces
(D) All of these

Q4. The back EMF of a synchronous motor depends on
(A) speed
(B) load
(C) load angle
(D) all of these

Q5. The minimum armature current of the synchronous motor corresponds to operation at
(A) zero leading power factor
(B) unity power factor
(C) 0.707 lagging power factor
(D) 0.707 leading power factor

Q6. Hunting in a synchronous motor can be minimized by
(A) using damper bars
(B) using a flywheel
(C) designing the motor for adequate synchronizing power
(D) any of the above methods.

Q7. What would happen if the direction of the field current in a 3 phase synchronous motor which is running clockwise is reversed
(A) the motor will continue to run in the same direction
(B) the motor will run in the reverse direction
(C) the motor will stop
(D) the winding of the motor will burn.

Q8. In which situation the negative phase sequences in a three phase synchronous motor exist
(A) motor is overloaded
(B) motor is under loaded
(C) unbalanced voltage is supplied
(D) motor armature is hot.

Q9. In which range the cost of a synchronous motor can be comparable to the cost of a induction motor ?
(A) Low HP high speed
(B) High HP low speed
(C) High HP high speed
(D) Low HP low speed.

Q10. In case of a 3 phase synchronous motor, maximum speed variation is
(A) 0.1
(B) 0.05
(C) 0.03
(D) Zero

Q11. An over-excited synchronous motor takes
(A) leading current
(B) lagging current
(C) Both of these
(D) none of the above

Q12. A synchronous motor can be used as a synchronous capacitor when it is
(A) under-loaded
(B) over-loaded
(C) under-excited
(D) over-excited

Q13. The power developed by a synchronous motor will be maximum when the load angle is
(A) zero
(B) 45°
(C) 90°
(D) 145°

Q14. In a synchronous motor total number of rotor slots is
(A) total number of stator slots
(B) more than total number of stator slots
(C) less than the total number of stator slots.
(D) None of these

Q15. The total steady state to drive synchronous motor and the load at synchronous speed is known as
(A) Synchronous torque
(B) Asynchronous torque
(C) Reluctance torque
(D) Pull-up torque.

Q16. The maximum torque which a synchronous will develop at rest for any angular positions of the rotor, at rated stator supply voltage and frequency, is known as
(A) Reluctance torque
(B) Synchronous torque
(C) Locked-rotor torque
(D) Pull up torque.

Q17. A three-phase synchronous motor will have
(A) no slip-rings
(B) one slip-ring
(C) two slip-rings
(D) six slip-rings

Q18. A synchronous motor can be started by
(A) pony motor
(B) D.C. compound motor
(C) providing damper winding
(D) All of these

Q19. A synchronous motor can develop synchronous torque
(A) when under loaded
(B) while over-excited
(C) only at synchronous speed
(D) below or above synchronous speed

Q20. The reason for synchronous motors are generally not self-starting
(A) the direction of rotation is not fixed
(B) the direction of instantaneous torque reverses after half cycle
(C) starters cannot be used on these machines
(D) starting winding is not provided on the machines