1. As the value of slip decrease, the efficiency of a three phase induction motor
(a) increases.
(b) decreases.
(c) become negative.
(d) remain same.
Answer
2. If the value of slip in a 3 phase induction motor is decreases, its rotor current
(a) increases.
(b) decreases.
(c) remain same.
(d) become zero.
Answer
3. If the value of slip in 3 phase induction motor is increases, the power factor of the rotor circuit
(a) increases.
(b) decreases.
(c) remain same.
(d) none of the above.
Answer
4. If a three phase induction motor is running at slip S, its copper losses is equal to
(a) S × rotor input.
(b) (1 – S) × rotor input.
(c) (1 + S) × rotor input.
(d) 1/S × rotor input.
Answer
5. The outer case winding of a double squirrel cage induction motor has
(a) higher resistance.
(b) low resistance.
(c) high inductance.
(d) high reactance.
Answer
6. When the supply voltage of 3 phase induction motor is doubled, then its torque
(a) reduced by half.
(b) become double.
(c) reduced by four time.
(d) increased by four time.
Answer
7. If a four pole induction motor has supply frequency of 50 Hz, then its synchronous speed is
(a) 1000 RPM.
(b) 1200 RPM.
(c) 1500 RPM.
(d) 1800 RPM.
Answer
8. With the increase in supply frequency, the synchronous speed of 3 phase induction motor
(a) increases.
(b) decreases.
(c) remains same.
(d) none of the above.
Answer
9. In single phase induction motor, starting winding is conducted in _______ with the main winding.
(a) series.
(b) parallel.
(c) series-parallel.
(d) none of the above.
Answer
10. In a single phase induction motor speed sensitive centrifugal switch is connected in
(a) series with main winding.
(b) parallel with main winding.
(c) series with starting winding.
(d) parallel with starting winding.
Answer
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