1. The basic operation of an induction motor is based on
(a) self induction.
(b) mutual induction.
(c) magnetic knocking.
(d) Lorentz Force.
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2. When the supply frequency of a three phase induction motor is increased, then its synchronous speed is
(a) decreases.
(b) increases.
(c) remain same.
(d) none of the above.
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3. In induction motor the unit of slip is
(a) rpm.
(b) metre per second.
(c) radian.
(d) unit less.
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4. If a 4-pole 50 Hz 3-phase induction motor run at 1440 rpm, then value of slip is
(a) 0.04%.
(b) 3.3%.
(c) 4%.
(d) 6%.
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5. When the rotor of a three phase induction motor is blocked its rotor frequency will become
(a) zero.
(b) half of supply frequency.
(c) equal to supply frequency.
(d) very high.
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6. When the rotor of 3 phase induction motor run at synchronous speed, its rotor frequency will become
(a) zero.
(b) half of supply frequency.
(c) equal to supply frequency.
(d) very high.
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7. When the rotor of three phase induction motor run at synchronous speed, the value of slip will be
(a) 0.
(b) 0.1.
(c) 0.5.
(d) 1.
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8. When the rotor of 3 phase induction motor is blocked, the value of slip will be
(a) zero.
(b) 0.1.
(c) 0.5.
(d) unity.
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9. Three phase slip ring induction motor is also known as
(a) controlled motor.
(b) wound rotor motor.
(c) synchronous motor.
(d) series motor.
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10. Which DC motor has similar characteristics as a three phase induction motor?
(a) DC shunt motor.
(b) DC series motor.
(c) DC cumulatively compound motor.
(d) DC differentially compound motor.
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11. When rotor resistance of a three phase induction motor become equal to its rotor reactance, its starting torque will be
(a) zero.
(b) maximum.
(c) unity.
(d) minimum.
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12. When the rotor of three phase induction motor is blocked, its rotor induced emf is
(a) zero.
(b) minimum.
(c) unity.
(d) maximum.
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13. The reactance of the rotor circuit of three phase induction motor is maximum at
(a) synchronous speed.
(b) full load.
(c) no load.
(d) stand-still condition.
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14. With the increase in supply voltage, the starting torque of a 3 phase induction motor
(a) increases.
(b) decrease.
(c) remains same.
(d) none of the above.
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15. If the slip of 3 phase induction motor is increases, the current in its stator winding
(a) increases.
(b) decreases.
(c) remains same.
(d) none of the above.
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