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

Sunday, August 5, 2018

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

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