Single phase motor mcq - electrical mcq (Multiple Choice Questions )

                                                Single phase motor mcq

important single phase motor mcq - electrical Multiple Choice Questions :-

                 

1         1.    At stand still condition the value of slip is

(a)   Zero

(b)  One

(c)   Infinity

(d)  None of the above

Ans – b

2         2.    If the terminal voltage of an induction motor is decreased then current

(a)   Increase

(b)  Decrease

(c)   Remain same

(d)  None

Ans--- b

3         3.      As compared to DOL starting method the star delta starting method must have

(a)   High starting current

(b)  Low starting current

(c)   High torque

(d)  Better acceleration

Ans ---- b

4          4.       Single phase motors are commercially manufactured up to

(a)   1 HP

(b)  2 HP

(c)   3 HP

(d)  4 HP

Ans --- b

5          5.       Which of the single phase motors will operate at high power factor –

(a)   capacitor start motor

(b)  shaded pole motor

(c)   capacitor run motor

(d)  split phase motor

Ans --- c

6          6.      motor used for driving the record player deck ---

(a)   hysteresis motor

(b)  dc series motor

(c)   synchronous motor

(d)  dc shunt motor

Ans ------ a

7           7.       a motor speed of 5000 rpm is required,which motor will you select---

(a)   Hysteresis motor

(b)  Shaded pole motor

(c)   Capacitor start motor

(d)  Universal motor

Ans ---- d

8            8.    universal motor is operated on no load, its speed is limited by---

(a)   windage and friction

(b)  armature weight

(c)   armature reaction

(d)  supply voltage

Ans ---- a

9               9.      which motor following  generally  used in ceiling fan ----

(a)   permanent capacitor type

(b)  capacitor start and run type

(c)   capacitor start type

(d)  split phase type

Ans---- a

1             10.   universal motor operates on ---

(a)   synchronous speed with varying load

(b)  constant speed and varying load

(c)   approximately constant speed and load

(d)  constant load and varying speed

Ans --- c

1             11.   Which of the following applications make use of a universal motor ---

(a)   Lathe machines

(b)  Floor polishing machine

(c)   Oil expeller

(d)  Portable tools

Ans --- d

1              12.   In portable tools the speed of the driven shaft is reduced by ---

(a)   Fluid coupling

(b)  Gearing

(c)   Chain drive

(d)  Belt drive

Ans – b

1               13.   The capacitance of a small single phase motor will be of the order of ---

(a)   Micro or pico farads

(b)  Farads

(c)   Few hundred farads

(d)  Kilo farads

Ans --- a

1              14.   Reluctance motors are

(a)   singly excited

(b)  doubly excited

(c)   both (a) and (b)

(d)  none of the above

Ans ---a

1             15.   Which motor is generally used for electric shavers

(a)   Universal motor

(b)  Shaded pole motor

(c)   Hysteresis motor

(d)  Reluctance motor

Ans – a

1             16.   motor generally used in toys is –

(a)   Reluctance motor

(b)  Shaded pole motor

(c)   Hysteresis motor

(d)  Two value capacitor motor

Ans ---b

1              17.   Which of the following is a reversible motor---

(a)   Capacitor start split phase motor

(b)  Universal motor

(c)   Both (A) and (B)

(d)  None

Ans --- c

1              18.   The starting torque of a single phase induction motor is ----

(a)   Zero

 (b)  Low

(c)   High

(d)  Uniform

Ans --- a

1               19.   The rotor for a hysteresis motor ---

(a)   is made of chrome steel

 (b)  has high hysteresis loss

(c)   has high retentivity

(d)  all of the above

Ans --- d

2               20.   What could be the smallest size of a universal motor ---

(a)   1/10 HP

(b)  1/20 HP

(c)   1/200 HP

(d)  None of the above

Ans – c

2                21.   The disadvantage of shaded pole motor is ----

(a)   very little over load capacity

(b)  low efficiency

(c)   low starting torque

(d)  all of the above

Ans –d

2                22.   Which of the following applications would need the smallest size of motor ---

(a)   Table fan

(b)  Electric clock

(c)   Domestic motor

(d)   Sewing machine

Ans --- b

2                23.    When a dc series motor is connected to ac supply, it will ---

(a)   give poor efficiency

(b)  run on poor power factor

(c)   spark excessively

(d)  all of the above

Ans --- d

2                   24.    In a shaded pole motor, the direction of rotation is from –

(a)   shaded pole to main pole

(b)  main pole to shaded pole

(c)   depends on supply line polarity

(d)  none of the above

 Ans ----b

                     25.   In a shaded pole motor, shading coils are used to—

(a)   reduce friction losses

(b)  produce rotating magnetic field

(c)   reduce windage losses

(d)   to protect against sparking

Ans ----- b