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Basic Electrical MCQs – General Science MCQs – 5

The torque in the case of a wound rotor induction motor
(A) Increases as rotor resistance is increased
(B) Decreases as rotor resistance is increased
(C) Remains unaffected by increase/decrease of rotor resistance
(D) Is maximum when rotor is shorted
Answer: Option A

The power output of induction motor will be maximum when
(A) The equivalent load resistance is equal to the standstill reactance of the motor
(B) The equivalent load resistance is equal to the resistance of the motor
(C) The equivalent load resistance is equal to the standstill leakage impedance of the motor
(D) The slip is zero
Answer: Option C

The speed of induction motor is
(A) Synchronous speed
(B) Synchronous speed × slip
(C) Synchronous speed/(1- slip)
(D) Synchronous speed × (1- slip)
Answer: Option D

Which of the following motors has high starting torque?
(A) A.C motor
(B) Induction motor
(C) Synchronous motor
(D) D.C series motor
Answer: Option D

The starting torque of the slip ring induction motor is increased by
(A) Adding external resistance to the rotor
(B) Adding the external inductance to the rotor
(C) Adding both external resistance and inductance to the rotor
(D) Adding external capacitance to the rotor
Answer: Option A

The torque developed by an induction motor corresponding to zero slip is equal to
(A) Maximum
(B) Full rated capacity
(C) Zero
(D) Minimum
Answer: Option C

Which of the following motors is most frequently used in industries?
(A) Synchronous motor (B) Commutator motor
(C) Single phase A.C motor
(D) 3 phase induction motor
Answer: Option D

An induction motor is
(A) Self-starting with zero torque
(B) Self-starting with high torque
(C) Self-starting with small torque than rated torque
(D) Self-starting with infinite torque
Answer: Option C

Full load current of a 10 HP, 3 phase, 440 V induction motor is of the order of
(A) 7 A
(B) 14 A
(C) 21 A
(D) 28 A
Answer: Option B

The starting current by a delta connected induction motor as compared to star connected motor under all other identical conditions is
(A) Same
(B) 2 times
(C) 3 times
(D) ½ times
Answer: Option C