Question 1

In a capacitor start motor, the phase displacement between starting and running winding can be nearly

Accepted Answer

A)  10°
B)  30°
C)  60°
D)  90° D

Question 2

Which of the following motors is used in mixies ?

Accepted Answer

A)  Repulsion motor
B)  Reluctance motor
C)  Hysteresis motor
D)  Universal motor D

Question 3

In repulsion motor direction of rotation of motor

Accepted Answer

A)  is opposite to that of brush shift
B)  is the same as that of brush shift
C)  is independent of brush shift
D)  none of the above B

Question 4

Short-circuiter is used in

Accepted Answer

A)  repulsion induction motor
B)  repulsion motor
C)  repulsion start induction run motor
D)  none of the above

Question 5

Which of the following motor will have relatively higher power factor ?

Accepted Answer

A)  Capacitor run motor
B)  Shaded pole motor
C)  Capacitor start motor
D)  Split phase motor

Question 6

If a particular application needs high speed and high starting torque, then which of the following motor will be preferred ?

Accepted Answer

A)  Universal motor
B)  Shaded pole type motor
C)  Capacitor start motor
D)  Capacitor start and run motor

Question 7

In a split phase motor, the running winding should have

Accepted Answer

A)  high resistance and low inductance
B)  low resistance and high inductance
C)  high resistance as well as high inductance
D)  low resistance as well as low inductiance

Question 8

The rotor developed by a single-phase motor at starting is

Accepted Answer

A)  more than i.he rated torque
B)  rated torque
C)  less than the rated torque
D)  zero

Question 9

In a split phase motor

Accepted Answer

A)  the starting winding is connected through a centrifugal switch
B)  the running winding is connected through a centrifugal switch
C)  both starting and running windings are connected through a centrifugal switch
D)  centrifugal switch is used to control supply voltage

Question 10

Direction of rotation of a split phase motor can be reversed by reversing the connection of

Accepted Answer

A)  running winding only
B)  starting winding only
C)  either (a)  or (b) 
D)  both (a)  and (b)

Question 11

In a shaded pole motor, the shading coil usually consist of

Accepted Answer

A)  a single turn of heavy wire which is in parallel with running winding
B)  a single turn of heavy copper wire which is short-circuited and carries only induced current
C)  a multilayer fine gauge copper wire in parallel with running winding
D)  none of the above

Question 12

The value of starting capacitor of a fractional horse power motor will be

Accepted Answer

A)  100 uF
B)  200 uF
C)  300 uF
D)  400 uF

Question 13

Which of the following motors is inherently self starting ?

Accepted Answer

A)  Split motor
B)  Shaded-pole motor
C)  Reluctance motor
D)  None of these

Question 14

Which of the following motor will give relatively high starting torque ?

Accepted Answer

A)  Capacitor start motor
B)  Capacitor run motor
C)  Split phase motor
D)  Shaded pole motor

Question 15

A centrifugal switch is used to dis- connect 'starting winding when motor has

Accepted Answer

A)  run for about 1 minute
B)  run for about 5 minutes
C)  picked up about 50 to 70 per cent of rated speed
D)  picked up about 10 to 25 per cent of rated speed

Question 16

In a shaded pole single-phase motor, the revolving field is produced by the use of

Accepted Answer

A)  inductor
B)  capacitor
C)  resistor
D)  shading coils

Question 17

In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to

Accepted Answer

A)  improve power factor
B)  increase overload capacity
C)  reduce fluctuations in torque
D)  to improve torque

Question 18

The range of efficiency for shaded pole motors is

Accepted Answer

A)  95% to 99%
B)  80% to 90%
C)  50% to 75%
D)  5% to 35%

Question 19

Burning out of windings is due to

Accepted Answer

A)  short circuited capacitor
B)  capacitor value hiving changed
C)  open circuiting of capacitor
D)  none of the above

Question 20

In a single phase motor the centrifugal switch

Accepted Answer

A)  disconnects auxiliary winding of the motor
B)  disconnects main winding of the motor
C)  reconnects the main winding the motor
D)  reconnects the auxiliary winding of the motor

Exam 1: Single-Phase Motor