MCQ Questions on Special Machines

1. By low voltage application, we can start a:

(a) Schrage motor
(b) Synchronous motor
(c) Slip ring induction motor
(d) DC compound motor [UPPCL (JE) – 2016]

2. The universal motor speed can be controlled by:

(a) Centrifugal mechanism only
(b) Resistance method only
(c) Any one of the given three methods
(d) Tapped field method only [JUVNL (JE) – 2017]

3. Punching machine is characterized as

(a) Continuous full load
(b) No load
(c) Continuous part load
(d) Impact load [JUVNL JE – 2017]

4. Generally used motor in domestic food mixer is:

(a) Capacitor start motor
(b) Shaded pole motor
(c) Universal motor
(d) Reluctance motor [NMRC – 2017]

5. Fractional horse power motors have power less than:

(a) 1 Kilo Watt
(b) 1 Mega Watt
 (c) 1 Watt
(d) 100 Watt

6. The motor having a smooth chrome-steel cylinder as its rotor with no rotor winding is

(a) Universal motor
(b) Hysteresis motor
(c) Repulsion motor
(d) Reluctance motor [DMRC JE – 2017]

7. The direction of rotation of hysteresis motor is determined by the

(a) Resistivity of the rotor material.
(b) Amount of hysteresis
(c) Permeability of rotor material
(d) Position of shaded pole w.r.t. main pole

8. A single phase motor draws a current of 5A from a 120V, 60 Hz line. The power factor of the motor is 65%. Calculate the active power absorbed by the motor.

(a) 600W
(b) 390W
(c) 456W
(d) 650W [J&K JE 2016]

9. In a split phase motor

(a) The starting winding is connected through a centrifugal switch.
(b) The running winding is connected through a centrifugal switch.
(c) Both the running winding and the starting winding is connected to centrifugal switch.
(d) Centrifugal switch is used to control supply voltage.

10. The running winding of a single phase motor on testing with Megger is found to be ground. Most probable location of the ground will be:

(a) At the end connections
(b) At the end terminals
(c) Anywhere on the winding inside a slot
(d) At the slot where coil enters or comes out of the slot

11. The repulsion start induction-run motor is used because of

(a) Good power factor
(b) High efficiency
(c) Minimum cost
(d) High starting torque

12. The wattage rating for a ceiling fan motor will be in the range of:

(a) 200 to 250 W
(b) 250 to 500 W
(c) 50 to 150 W
(d) 10 to 20 W

13. The stepper motor has six phase winding on its stator and has 12 teeth on rotor. The stepping angle is:

(a) 5 degrees
(b) 10 degrees
(c) 2.5 degrees
(d) 30 degrees [FCI – 2015]

14. In hand tool applications, the single-phase motor used is

(a) AC series motor
(b) Shaded pole motor
(c) Capacitor start motor
(d) Capacitor run motor

15. Speed of a repulsion motor at No load is:

(a) Low
(b) Very low
(c) High
(d) Dangerously high

16. Which type of motor is most suitable for computer printer device? [Uttarakhand AE 2013]

(a) Reluctance motor
(b) Hysteresis motor
(c) Shaded pole motor
(d) Stepper motor

17. In a split phase motor, the ratio of number of turns for starting winding to that for running winding is:

(a) 2.0
(b) More than 1.0
(c) 1.0
(d) Less than 1.0

18. A 3-stack, variable reluctance step motor has 20 poles on each rotor and stator stack. The step angle of this step motor is:

(a) 30
(b) 6°
(c) 9°
(d) 18°

19. Which of the following is an unexcited single phase synchronous motor? [Uttarakhand AE – 2013]

(a) A.C. Series motor
(b) Reluctance motor
(c) Universal motor
(d) Repulsion motor

20. The common type of servo motor is different from normal induction motor as it has

(a) Lower rotor resistance
(b) Higher rotor resistance
(c) Higher power rating
(d) Larger inertia

21. The capacitors used in single-phase motors have no

(a) definite value
(b) polarity marking
(c) voltage rating
(d) dielectric medium [BSNL TTA – 2016]

22. The position of shaded pole with respect to the main pole determines the

(a) Direction of a split phase motor
(b) Direction of flow of current
(c) Direction of rotation of a hysteresis motor
(d) Direction of rotation of a squirrel cage motor

23. One among the following types of torque has the highest numerical value, in a stepper motor. Identify the type. [UPRVUNL 2014]

(a) Detent torque
(b) Holding torque
(c) Dynamic torque
(d) Ripple torque

24. Which of the following statements is incorrect regarding a universal motor?

(a) It’s direction of rotation can be reversed by reversing the polarity of its power supply
(b) It is designed for commercial frequency ranging zero to 60 Hz
(c) It is usually built into the device it drives
(d) It is built in small size up to 0.5 kW

25. Locked rotor current of a shaded pole motor with respect to full load current is:

(a) Equal
(b) Less
(c) Slightly more
(d) Several times more