Single Phase Induction Motors MCQs

Option A: voltage rating

Option B: dielectric medium

Option C: polarity marking

Option D: definite value

Correct Answer: polarity marking ✔

Option A: spark excessively

Option B: have poor efficiency

Option C: have poor power factor

Option D: all of the above

Correct Answer: all of the above ✔

A. can be operated either on D.C. or A.C. supply at approximately the same speed and output
B. can be marketed internationally
C. runs at dangerously high speed on no-load

Correct Answer: A. can be operated either on D.C. or A.C. supply at approximately the same speed and output ✔

Option A: through resistance

Option B: through reactances

Option C: through capacitors

Option D: solidly

Correct Answer: through resistance ✔

Option A: slip rings

Option B: commutator

Option C: both A. and (b)

Option D: none of the above

Correct Answer: commutator ✔

Option A: Repulsion motor

Option B: Repulsion induction motor

Option C: Repulsion start induction run motor

Option D: None of the above

Correct Answer: Repulsion induction motor ✔

Option A: It cannot be reversed, ordinarily

Option B: It requires no D.C. field excitation for its operation

Option C: It is nothing else but a single-phase, salient pole synchronous-induction motor

Option D: Its squirrel cage-rotor is of unsym-metrical magnetic construction in order to vary reluctance path between stator and rotor

Correct Answer: It cannot be reversed, ordinarily ✔

Option A: centrifugal switch

Option B: capacitor

Option C: commutator

Option D: all of the above

Correct Answer: all of the above ✔

Option A: disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding

Option B: disconnect motor from supply and immediately reconnect it to supply with reversed connections of the main winding

Option C: reverse the direction of connection of the auxiliary winding and after motor comes to rest then connect auxiliary winding to the supply

Option D: reverse the direction of connections of the auxiliary winding and immediately connect it to supply

Correct Answer: disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding ✔

Option A: become unstable

Option B: draw excessive armature current and may burn out

Option C: fall out of synchronism and come to stand still

Option D: run as induction motor

Correct Answer: run as induction motor ✔

Option A: hard and annealed bearings

Option B: ball or roller bearings

Option C: soft and porous bearings

Option D: plain or sleeve bearings

Correct Answer: plain or sleeve bearings ✔

Option A: open armature winding

Option B: shorted armature winding

Option C: shorted field winding”

Option D: high commutator mica

Correct Answer: all of the above ✔

Option A: It is similar to reluctance motor

Option B: It is basically an induction motor and not a synchronous one

Option C: So far as its basic working principle is concerned, it is similar to shaded pole motor

Option D: the air-gap between rotor and salient poles is non- uniform

Correct Answer: It is similar to reluctance motor ✔

Option A: run faster

Option B: spark at light loads

Option C: draw excessive current and overheat

Option D: run slower

Correct Answer: draw excessive current and overheat ✔

Option A: motor will not come up to speed

Option B: motor will not carry the load

Option C: current drawn by the motor will be excessively high

Option D: electrolytic capacitor will, in all probability, suffer break down

Correct Answer: electrolytic capacitor will, in all probability, suffer break down ✔

Option A: It is a reversing motor

Option B: It is preferred to permanent-split single-value capacitor motor where frequent reversals are required

Option C: It has low starting as well as rushing currents

Option D: It has high starting torque

Correct Answer: It is preferred to permanent-split single-value capacitor motor where frequent reversals are required ✔

Option A: worn bearings

Option B: short-circuit in the winding

Option C: open-circuit in the winding

Option D: none of the above

Correct Answer: worn bearings ✔

Option A: it is comparatively cheaper

Option B: it has almost non-destructible capacitor

Option C: it has low starting as well as running currents at relatively high power factor

Option D: it is quiet in operation

Correct Answer: it has low starting as well as running currents at relatively high power factor ✔

Option A: Hysteresis motor

Option B: Reluctance motor

Option C: Capacitor-run motor

Option D: Universal motor

Correct Answer: Hysteresis motor ✔

Option A: magnetic relay

Option B: thermal relay

Option C: centrifugal switch

Option D: none of the above

Correct Answer: magnetic relay ✔

Option A: 30 to 40

Option B: 70 to 80

Option C: 80 to 90

Option D: 100

Correct Answer: 70 to 80 ✔

Option A: Induction motor

Option B: Three-phase series motor

Option C: Schrage motor

Option D: Hysteresis motor

Correct Answer: Three-phase series motor ✔

Option A: Hysteresis motor

Option B: Schrage motor

Option C: Universal motor

Option D: Reluctance motor

Correct Answer: Schrage motor ✔

Option A: brush axis is 45° electrical to field axis

Option B: brush axis coincides with the field axis

Option C: brush axis is 90° electrical to field axis

Option D: both B. and (c)

Correct Answer: D. both B. and (c) ✔

Option A: d.c. series motor

Option B: shaded pole motor

Option C: capacitor-start capacitor-run motor

Option D: reluctance motor

Correct Answer: capacitor-start capacitor-run motor ✔

Option A: provide mechanical balance

Option B: improve power factor and provide better speed regulation

Option C: prevent hunting in the motor

Option D: eliminate armature reaction

Correct Answer: improve power factor and provide better speed regulation ✔

Option A: improves the efficiency

Option B: helps the rotor teeth to remain under the stator teeth

Option C: helps in reducing the tendency of the rotor teeth to remain under the stator teeth

Option D: improves the power factor

Correct Answer: helps in reducing the tendency of the rotor teeth to remain under the stator teeth ✔

Option A: secondary winding surrounds the primary winding

Option B: primary winding surrounds the secondary winding

Option C: both are usual arrangements

Option D: none of the above

Correct Answer: secondary winding surrounds the primary winding ✔

Option A: A.C. motor

Option B: D.C. shunt motor

Option C: D.C. series motor

Option D: none of the above

Correct Answer: C. D.C. series motor ✔

Option A: high starting torque

Option B: low starting torque

Option C: medium starting torque

Option D: very high starting torque

Correct Answer: low starting torque ✔

Option A: damage to the starting winding

Option B: damage to the centrifugal switch

Option C: overloading of running winding

Option D: none of the above

Correct Answer: damage to the starting winding ✔

Option A: shunt motor

Option B: series motor

Option C: compound motor

Option D: separately excited motor

Correct Answer: compound motor ✔

Option A: thin wire placed at the top of the slots

Option B: thin wire placed at the bottom of the slots

Option C: thick wire placed at the bottom of the slots

Option D: thick wire placed at the top of the” slots

Correct Answer: thick wire placed at the bottom of the slots ✔

Option A: brush axis is at 45° electrical to the field axis

Option B: brush axis coincides with the field axis

Option C: brush axis is at 90° electrical to the field axis

Option D: none of the above

Correct Answer: brush axis is at 45° electrical to the field axis ✔

Option A: aluminium

Option B: cast iron

Option C: chrome steel

Option D: copper

Correct Answer: chrome steel ✔

Option A: Vacuum cleaners

Option B: Fan motors

Option C: Pistol drills

Option D: All of the above

Correct Answer: Pistol drills ✔

Option A: pulsating

Option B: uniform

Option C: none of the above

Option D: nil

Correct Answer: nil ✔

Option A: friction

Option B: varying the resistance

Option C: tapping the field

Option D: centrifugal mechanism

Correct Answer: varying the resistance ✔

Option A: capacitor run motor

Option B: hysteresis motor

Option C: universal motor

Option D: repulsion motor

Correct Answer: universal motor ✔

Option A: retentivity

Option B: resistivity

Option C: susceptibility

Option D: none of the above

Correct Answer: retentivity ✔

Option A: equal to full load current

Option B: less than full load current

Option C: slightly more than full load current

Option D: several times the full load current

Correct Answer: slightly more than full load current ✔

Option A: It requires more maintenance of commutator and other mechanical devices

Option B: It makes quite a bit of noise on starting

Option C: In fractional horse power motors, it has replaced the capacitor motors

Option D: It is not easily reversed

Correct Answer: In fractional horse power motors, it has replaced the capacitor motors ✔

Option A: running winding

Option B: rotor winding

Option C: field winding

Option D: compensating winding

Correct Answer: running winding ✔

Option A: smaller brush width

Option B: less number of field turns

Option C: more number of armature turns

Option D: less air gap

Correct Answer: all of the above ✔

Option A: it revolves synchronously

Option B: it is not subject to any magnetic or mechanical vibrations

Option C: it can be easily manufactured in extremely small sizes of up to 1 W output

Option D: it develops hysteresis torque which is extremely steady both in amplitude and phase

Correct Answer: it develops hysteresis torque which is extremely steady both in amplitude and phase ✔

Option A: It requires only one winding

Option B: It can rotate in one direction only

Option C: It is self-starting

Option D: It is not self-starting

Correct Answer: It is not self-starting ✔

Option A: varying field flux with tapped field windings

Option B: connecting rheostat in series

Option C: applying variable voltage by means of silicon controlled rectifier

Option D: applying variable voltage by means of variable auto-transformer

Correct Answer: all of the above methods ✔

Option A: It is extremely sensitive to fluctuations in supply voltage

Option B: Its high starting torque is due to its high rotor hysteresis loss

Option C: It is extremely quiet in operation

Option D: It accelerates from rest to full-speed almost instantaneously

Correct Answer: It is extremely sensitive to fluctuations in supply voltage ✔

Option A: armature

Option B: field

Option C: rotor

Option D: stator

Correct Answer: stator ✔

Option A: gearing

Option B: belts

Option C: brakes

Option D: chains

Correct Answer: gearing ✔

Option A: is self-starting

Option B: is constant speed motor

Option C: needs no D.C. excitation

Option D: all of the above

Correct Answer: all of the above ✔

Option A: Split phase motor

Option B: Universal motor

Option C: Hysteresis motor

Option D: Shaded pole motor

Correct Answer: Hysteresis motor ✔

Option A: fans

Option B: blowers

Option C: sound equipment

Option D: mixer grinders

Correct Answer: sound equipment ✔

Option A: armature winding

Option B: field winding

Option C: either armature winding or field winding

Option D: none of the above

Correct Answer: armature winding ✔

Option A: high inductance of field and armature circuits

Option B: induced current in rotor due to variations of flux

Option C: fine copper wire winding

Option D: none of the above

Correct Answer: high inductance of field and armature circuits ✔

Option A: Split phase motor

Option B: Reluctance motor

Option C: Hysteresis motor

Option D: Universal motor

Correct Answer: Hysteresis motor ✔

Option A: gear trains

Option B: V-belts

Option C: brakes

Option D: chains

Correct Answer: gear trains ✔

Option A: Universal motor

Option B: Repulsion motor

Option C: Capacitor motor

Option D: All single phase motors have zero starting torque

Correct Answer: Capacitor motor ✔

Option A: Capacitor run motor

Option B: Shaded pole motor

Option C: Hysteresis motor

Option D: Schrage motor

Correct Answer: Schrage motor ✔

Option A: Gradually varying load

Option B: Non-reversing, no-load start

Option C: Reversing, light start

Option D: Reversing, heavy start

Correct Answer: Reversing, heavy start ✔

Option A: 200 to 250 W

Option B: 250 to 500 W

Option C: 50 to 150 W

Option D: 10 to 20 W

Correct Answer: 50 to 150 W ✔

Option A: 100 to 150 W

Option B: 40 to 75 W

Option C: 10 to 30 W

Option D: 5 to 10 W

Correct Answer: 100 to 150 W ✔

Option A: End play

Option B: Air gap

Option C: Insulation in rotor

Option D: Balancing of rotor

Correct Answer: Balancing of rotor ✔

Option A: good power factor

Option B: high efficiency

Option C: minimum cost

Option D: high starting torque

Correct Answer: high starting torque ✔

Option A: from main pole to shaded pole

Option B: from shaded pole to main pole

Option C: either of the above depending on voltage

Option D: either of the above depending on power factor

Correct Answer: from main pole to shaded pole ✔

Option A: Resistance start

Option B: Capacitor start capacitor run

Option C: Shaded pole

Option D: Universal

Correct Answer: Shaded pole ✔

Option A: Repulsion motor

Option B: Shaped pole motor

Option C: Capacitor-start motor

Option D: Split-phase motor

Correct Answer: Capacitor-start motor ✔

Option A: Universal motor

Option B: Repulsion motor

Option C: Synchronous motor

Option D: Reluctance motor

Correct Answer: Universal motor ✔

Option A: reduce the effects of armature reaction

Option B: increase the torque

Option C: reduce sparking at the brushes

Option D: none of the above

Correct Answer: reduce sparking at the brushes ✔

Option A: air capacitor

Option B: paper spaced oil filled type

Option C: ceramic type

Option D: a.c. electrolytic type

Correct Answer: paper spaced oil filled type ✔

Option A: thick wire placed at the bottom of the slots

Option B: thick wire placed at the top of the slots

Option C: thin wire placed at the top of the slots

Option D: thin wire placed at the bottom of the slots

Correct Answer: thin wire placed at the top of the slots ✔

Option A: 0.6 power factor lagging

Option B: 0.8 power factor lagging

Option C: 0.8 power factor leading

Option D: unity power factor

Correct Answer: 0.6 power factor lagging ✔

Option A: Shaped pole motor

Option B: Split phase motor

Option C: Capacitor start motor

Option D: Capacitor run motor

Correct Answer: Capacitor run motor ✔

Option A: Reluctance motor

Option B: Series motor

Option C: Repulsion motor

Option D: Universal motor

Correct Answer: Reluctance motor ✔

Option A: zero slip

Option B: negative slip

Option C: positive slip

Option D: all of the above

Correct Answer: all of the above ✔

Option A: A.C. only

Option B: D.C. only

Option C: either A.C. or D.C.

Option D: none of the above

Correct Answer: C. either A.C. or D.C. ✔

Option A: Shaded pole motor

Option B: Hysteresis motor

Option C: Two value capacitor motor

Option D: Universal motor

Correct Answer: Hysteresis motor ✔

Option A: inherently self-starting with high torque

Option B: inherently self-starting with low torque

Option C: inherently non-self-starting with low torque

Option D: inherently non-self-starting with high torque

Correct Answer: inherently non-self-starting with low torque ✔

Option A: Electric shavers

Option B: Refrigerators

Option C: Signalling and timing devices

Option D: Lifts and hoists

Correct Answer: Signalling and timing devices ✔

Option A: universal motor

Option B: D.C. shunt motor

Option C: single-phase capacitor run motor

Option D: 3-phase synchronous motor

Correct Answer: single-phase capacitor run motor ✔

Option A: hysteresis loss

Option B: magnetisation of rotor

Option C: eddy current loss

Option D: electromagnetic induction

Correct Answer: hysteresis loss ✔

Option A: D.C. shunt motor

Option B: Schrage motor

Option C: Repulsion start and induction run motor

Option D: Universal motor

Correct Answer: Schrage motor ✔

Option A: lagging

Option B: always leading

Option C: unity

Option D: unity to 0.8 leading

Correct Answer: lagging ✔

Option A: toys

Option B: hair dryers

Option C: circulators

Option D: any of the above

Correct Answer: any of the above ✔

Option A: torque will increase

Option B: the motor will consume less power

Option C: motor will run in reverse direction

Option D: motor will continue to run in same direction

Correct Answer: motor will continue to run in same direction ✔

Option A: repulsion induction motor

Option B: repulsion motor

Option C: repulsion start induction run motor

Option D: none of the above

Correct Answer: repulsion start induction run motor ✔

Option A: 95% to 99%

Option B: 80% to 90%

Option C: 50% to 75%

Option D: 5% to 35%

Correct Answer: 5% to 35% ✔

Option A: short circuited capacitor

Option B: capacitor value hiving changed

Option C: open circuiting of capacitor

Option D: none of the above

Correct Answer: short circuited capacitor ✔

Option A: running winding only

Option B: starting winding only

Option C: either A. or (b)

Option D: both A. and (b)

Correct Answer: C. either A. or (b) ✔

Option A: Split motor

Option B: Shaded-pole motor

Option C: Reluctance motor

Option D: None of these

Correct Answer: Shaded-pole motor ✔

Option A: interchanging the supply leads

Option B: position of shaded pole with respect to main pole

Option C: retentivity of the rotor material

Option D: none of these

Correct Answer: position of shaded pole with respect to main pole ✔

Option A: start and then stop

Option B: start and run slowly

Option C: start and run at rated speed

Option D: not start at all

Correct Answer: not start at all ✔

Option A: Repulsion motor

Option B: Reluctance motor

Option C: Hysteresis motor

Option D: Universal motor

Correct Answer: Universal motor ✔

Option A: disconnects auxiliary winding of the motor

Option B: disconnects main winding of the motor

Option C: reconnects the main winding the motor

Option D: reconnects the auxiliary winding of the motor

Correct Answer: disconnects auxiliary winding of the motor ✔

Option A: at the end connections

Option B: at the end terminals

Option C: anywhere on the winding inside a slot

Option D: at the slot edge where coil enters or comes out of the slot

Correct Answer: at the slot edge where coil enters or comes out of the slot ✔

Option A: 100 uF

Option B: 200 uF

Option C: 300 uF

Option D: 400 uF

Correct Answer: 300 uF ✔

A. is opposite to that of brush shift
B. is the same as that of brush shift
C. is independent of brush shift

Correct Answer: is the same as that of brush shift ✔

Option A: run for about 1 minute

Option B: run for about 5 minutes

Option C: picked up about 50 to 70 per cent of rated speed

Option D: picked up about 10 to 25 per cent of rated speed

Correct Answer: picked up about 50 to 70 per cent of rated speed ✔

Option A: inductor

Option B: capacitor

Option C: resistor

Option D: shading coils

Correct Answer: shading coils ✔

Option A: Universal motor

Option B: Shaded pole type motor

Option C: Capacitor start motor

Option D: Capacitor start and run motor

Correct Answer: Universal motor ✔