MCQs on DC Motor

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1. Ward Leonard method of speed control is basically a
(a) field control method.
(b) armature controlled method.
(c) field diverter.
(d) frequency control method.

 2. When the armature current of DC series motor is reduced by half it torque will
(a) reduce by half.
(b) reduced by four time.
(c) remain same.
(d) become double.

 3. In a dc machine, the angle between main field axis and brush axis is kept 90° in order to have
(a) constant torque.
(b) constant speed.
(c) maximum torque.
(d) maximum speed.

 4. If the field current of separately excited DC motor is increased, then the speed of the motor
(a) decreases.
(b) increases.
(c) remain same.
(d) none of the above.

 5. Which of the following motor is used for shear and punch?
(a) series motor.
(b) shunt motor.
(c) cumulatively compound motor.
(d) defferentially compound motor.

 6. For which of the following DC motor, Swinburne test is applicable?
(a) Series motor.
(b) Shunt motor.
(c) cumulatively compound motor.
(d) differential compound motor.  

 7. In a dc compound motor the field regulator is provided to
(a) control the flux.
(b) limit the armature current.
(c) demagnatize field partially.
(d) none of the above.

 8. In DC Motors, Swinburne test is conducted at
(a) no load.
(b) full load.
(c) half load.
(d) any load.

 9. In DC Motors, Hopkinson test is conducted at
(a) no load.
(b) half load.
(c) full load.
(d) any  load.

 10. If the back emf in a dc motor vanishes sundenly, the motor will
(a) start hunting.
(b) burn.
(c) run at very high speed.
(d) run noisy.

 11. Mechanical power developed by a DC series motor is maximum when its back EMF is
(a) equal to supply voltage.
(b) zero.
(c) half of supply voltage.
(d) double to the supply voltage.  

 12. Field weaking method of a DC motor is also known as
(a) constant voltage control method.
(b) constant frequency control method.
(c) constant current control method.
(d) constant power control method.

 13. The output indicated on the name plate of any motor is always the
(a) gross power.
(b) power drawn in kVA.
(c) power drawn in kW.
(d) output power at the shaft 

 14. In DC motor, armature resistance control method is also known as
(a) constant torque control.
(b) constant power control.
(c) constant voltage control.
(d) constant current control. 

 15. Which of the following motor is mainly used in tape recorders?
(a) Reluctance motor.
(b) Shaded pole motor.
(c) Servo Motor.
(d) Hysteresis motor.

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