301 MCQ Questions on Induction Motors

301. If the rotor circuit resistance of a 3 phase induction motor is increased, then

(a) The starting torque will increase but the maximum torque will remain unchanged.
(b) Both the starting and the maximum torque will decrease.
(c) The starting torque will decrease but the maximum torque will remain unchanged.
(d) Both the starting and the maximum torque will increase.

302. The rotor power output of a 3 phase induction motor is 15 kW and the corresponding slip is 4%. The rotor copper losses will be:

(a) 625 W
(b) 525 W
(c) 500 W
(d) 600 W [UPPCL (AE) – 2015]

303. The output power of any electric motor is taken from

(a) Frame
(b) Commutator
(c) Coupling mounted on shaft
(d) Armature [RRB JE – 2015]

304. Rotating magnetic field is produced in a

(a) Single-phase induction motor
(b) Three-phase induction motor
(c) D.C. series motor
(d) A.C. series motor [RRB JE – 2015]

305. To use an AC motor in a DC circuit, Which equipment would be required additionally? [RRB SSE – 2014]

(a) Inductor
(b) Capacitor
(c) Rectifier
(d) Inverter

306. Single phase induction motor is also known as:

(a) Multi horse power motor
(b) Single horse power motor
(c) Fraction horse power motor
(d) Double horse power motor

307. Voltage limit for AC single phase induction motor is:

(a) 3 kV
(b) 1.5 kV
(c) 250 V
(d) 11 kV [UPPCL (JE) 2016]

308. Which type of 1-φ induction motor is relatively free from mechanical and magnetic vibrations?

(a) Universal motor
(b) Hysteresis motor
(c) Shaded pole motor
(d) Reluctance motor

309. As per double field revolving theory with slip denoted by s:

(a) The forward flux has a slip of s: and backward flux have a slip of 2 – s
(b) The forward flux has a slip of 2 – s; and backward flux have a slip of s.
(c) The forward flux has a slip of 2 + s; and backward flux have a slip of 2 – s
(d) The forward flux and backward flux have a slip of s.

310. The torque in a single phase motor is given by:

(a) Backward torque
(b) Forward torque
(c) Forward torque – backward torque
(d) Forward torque + backward torque

311. For starting a single phase induction motor the auxiliary winding and the main winding are spaced apart by:

(a) 270°
(b) 90°
(c) 180°
(d) 0

312. In a single phase induction motor the stator winding produces a flux which is:

(a) Alternating
(b) Alternating and rotating
(c) Rotating
(d) Constant everywhere

313. Which of the following motor is suitable for frequent starting and stopping?

(a) Capacitor start motor
(b) Capacitor start capacitor run motor
(c) Resistance split phase motor
(d) All of the above

314. In a single phase induction motor, the starting torque developed is proportional to:

(a) Supply voltage V
(b) V²
(c) 1/V²
(d) 1/V