Question 1

After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on&#10;A)running winding&#10;B)rotor winding&#10;C)field winding&#10;D)compensating winding

Accepted Answer

After the starting winding of a single-phase induction motor is disconnected, the motor continues to run only on the running winding. The running winding is designed to handle the motor's operation after it has reached a certain speed, and the starting winding is no longer needed.

Question 2

Which of the following statements regarding repulsion-start induction motor is incorrect ?&#10;A)It requires more maintenance of commutator and other mechanical devices&#10;B)It makes quite a bit of noise on starting&#10;C)In fractional horse power motors, it has replaced the capacitor motors&#10;D)It is not easily reversed

Accepted Answer

Repulsion-start induction motors have not replaced capacitor motors in fractional horsepower applications; capacitor motors are still widely used due to their efficiency and simplicity.

Question 3

A.C. series motor as compared to D.C. series motor has&#10;A)smaller brush width&#10;B)less number of field turns&#10;C)more number of armature turns&#10;D)all of the above

Accepted Answer

A.C. series motors are designed differently from D.C. series motors to accommodate the characteristics of alternating current. They typically have smaller brush width to reduce the effects of AC on the commutation process, less number of field turns to limit the inductance which can impede AC flow, and more number of armature turns to ensure adequate torque production despite the inductive reactance present in AC systems.

Question 4

Locked rotor current of a shaded pole motor is&#10;A)equal to full load current&#10;B)less than full load current&#10;C)slightly more than full load current&#10;D)several times the full load current

Accepted Answer

The answer of Locked rotor current of a shaded pole...

Question 5

Speed control of a universal motor is achieved by&#10;A)varying field flux with tapped field windings&#10;B)connecting rheostat in series&#10;C)applying variable voltage by means of silicon controlled rectifier&#10;D)all of the above methods

Accepted Answer

Speed control of a universal motor can be achieved through various methods including varying the field flux with tapped field windings, connecting a rheostat in series with the motor, and applying variable voltage using silicon controlled rectifiers (SCRs). Each of these methods adjusts the motor's speed by altering the electrical input or the motor's internal electrical characteristics.

Question 6

Hysteresis motor is particularly useful for high-quality record players and tape- recorders because&#10;A)it revolves synchronously&#10;B)it is not subject to any magnetic or mechanical vibrations&#10;C)it can be easily manufactured in extremely small sizes of upto 1 W output&#10;D)it develops hysteresis torque which is extremely steady both in amplitude and phase

Accepted Answer

Hysteresis motor develops hysteresis torque which is extremely steady both in amplitude and phase. This makes it particularly useful for high-quality record players and tape-recorders.

Question 7

Which of the following statements regarding hysteresis motor is in incorrect ?&#10;A)It is extremely sensitive to fluctuations in supply voltage&#10;B)Its high starting torque is due to its high rotor hysteresis loss&#10;C)It is extremely quiet in operation&#10;D)It accelerates from rest to full-speed almost instantaneously

Accepted Answer

Hysteresis motors are not extremely sensitive to fluctuations in supply voltage; they are known for their ability to maintain constant speed despite voltage changes.

Question 8

Which of the following statements regarding single-phase induction motoris correct ?&#10;A)It requires only one winding&#10;B)It can rotate in one direction only&#10;C)It is self-starting&#10;D)It is not self-starting

Accepted Answer

Single-phase induction motors are not self-starting because the stator produces a pulsating magnetic field, not a rotating magnetic field. Additional components or mechanisms, like capacitors or shaded poles, are needed to create a phase difference and start the motor.

Question 9

The starting winding of a single-phase motor is placed in&#10;A)armature&#10;B)field&#10;C)rotor&#10;D)stator

Accepted Answer

The starting winding of a single-phase motor is placed in the stator. This winding is used to provide the necessary phase difference between the currents in the main and auxiliary windings, creating a rotating magnetic field needed to start the motor.

Question 10

The speed of a universal motor is usually reduced by using&#10;A)gearing&#10;B)belts&#10;C)brakes&#10;D)chains

Accepted Answer

Gearing is commonly used to reduce the speed of a universal motor by mechanically adjusting the output speed while maintaining torque.

Deck 5: Single-Phase Induction Motors and Their Features