# SSC JE Single Phase Induction Motor Solved Question (2021-2009)

Ques.51.  Each of the following statements regarding a shaded pole motor is correct except (SSC-2015)

1. It has high starting torque
2. Its direction of rotation is from unshaded pole to shaded pole portion of the poles
3. It has a very poor power factor
4. It has very high efficiency

Answer.1. It has high starting torque

Explanation:-

The shaded-pole motor is the original type of AC single-phase induction motor. A shaded-pole motor is a small squirrel-cage motor in which the auxiliary winding is composed of a copper ring or bar surrounding a portion of each pole. This auxiliary single-turn winding is called a shading coil. Since the phase angle between the shaded and unshaded sections is small, shaded pole motors produce only a small starting torque relative to torque at full speed.

The shaded pole motor has the lowest starting torque as compared to the all single-phase induction motors.

Ques.52. Which of the following motor is used in the mixer? (SSC-2015)

1. Reluctance motor
2. Universal Motor
3. Repulsion Motor
4. Hysteresis Motor

Explanation:-

We use universal motors in mixer grinders. Universal motors can run both on a.c. and d.c.These motors have high starting torque and speed, hence these are most preferred.

Ques.53. Which of the following motors can be run on A.C as well as D.C supply? (SSC-2014)

1. Reluctance Motor
2. Universal Motor
3. Repulsion Motor
4. Synchronous Motor

Explanation:-

• The universal motor is so named because it is a type of electric motor that can operate on AC or DC power.
• It is a commutated series-wound motor where the stator’s field coils are connected in series with the rotor windings through a commutator.
• It is often referred to as an AC series motor. The universal motor is very similar to a DC series motor in construction but is modified slightly to allow the motor to operate properly on AC power.
• This type of electric motor can operate well on AC because the current in both the field coils and the armature (and the resultant magnetic fields) will alternate (reverse polarity) synchronously with the supply.

Ques.54. Which of the following motor will give a relatively high starting torque? (SSC-2014)

2. Capacitor start motor
3. Capacitor run motor
4. Split phase motor

Explanation:-

A Capacitor Start Motors is a single phase Induction Motor that employs a capacitor in the auxiliary winding circuit to produce a greater phase difference between the current in the main and the auxiliary windings. Due to greater phase difference capacitor Start motors have very high starting torque for a single-phase AC motor.

Ques.55. The repulsion-start induction-run motor is used because of (SSC-2014)

1. High starting torque
2. Good Power factor
3. High efficiency
4. Minimum cost

Explanation:-

• A repulsion motor is a type of electric motor for using on alternating current (AC). It was formerly used as a traction motor for electric trains.
• Repulsion motors are classified under single-phase motors. In repulsion motors, the stator windings are connected directly to the AC power supply and the rotor is connected to a commutator and brush assembly, similar to that of a direct current (DC) motor
• The starting torque of the repulsion start motor is 350 percent with moderate starting current.
• It is usually applicable where the starting period is of a long duration because of high inertia of the load. such as the high-speed lift.

Ques.56. The least expensive fractional horsepower motor is ________  (SSC-2014)

1. Ac series motor
3. Capacitor start motor
4. Split phase motor

Explanation:-

Shaded pole motor is small in size and less expensive to manufacture. These motors are also called as fractional KW motors because most of these motors are constructed in fractional kilo-watt capacity.

Ques.57. In which of the single-phase motor the rotor has no teeth or winding? (SSC-2014)

1. Universal motor
2. Split phase Motor
3. Reluctance Motor
4. Hysteresis motor

Explanation:-

Hysteresis motor doesn’t have teeth or winding, therefore, these motor are free from mechanical vibration.

Ques.58. Which of the following single-phase motor is available with speed as low as one revolution per minute? (SSC-2014)

2. Reluctance
3.  Hysteresis
4.  Universal

Explanation:-

The above figure shows the 3 speed shaded pole motor. The main winding is the speed winding for high-speed operation. For medium-speed operation, the main winding is connected in series with medium-speed winding which increases the number of poles and produces fewer revolutions per minute.

And for further reduction in speed, the main winding is connected in series with medium and low-speed operation thus increasing the number of poles in the stator and reducing speed upto one revolution per minute.

Ques.59. A vacuum cleaner employs________ motor (SSC-2014)

1. Resistance split phase
2. Capacitor start
4. Single-phase series

Explanation:-

To create vacuum high-speed motors are required. Ac series motor is best suited as they can be operated at very high speed.

Ques.60.  In a capacitor start single phase induction motor, the current in the (SSC-2014)

1. Supply lines leads the voltage
2. Starting winding lags the voltage
3. Main winding leads the voltage
4. Starting winding leads the voltage