A. zero frequency
B. the same frequency as the slip frequency
C. the same phase as the rotor e.m.f.
D. high value for the satisfactory speed control
Related Mcqs:
- A 3-phase 440 V, 50 Hz induction motor has 4% slip. The frequency of rotor e.m.f. will be____________?
A. 200 Hz
B. 50 Hz
C. 2 Hz
D. 0.2 Hz - In a three-phase induction motor, the number of poles in the rotor winding is always__________?
A. zero
B. more than the number of poles in stator
C. less than number of poles in stator
D. equal to number of poles in stator - If an induction motor with certain ratio of rotor to stator slots, runs at 1/7 of the normal speed, the phenomenon will be termed as____________?
A. humming
B. hunting
C. crawling
D. cogging - In an induction motor the relationship between stator slots and rotor slots is that_____________?
A. stator slots are equal to rotor slots
B. stator slots are exact multiple of rotor slots
C. stator slots are not exact multiple of rotor slots
D. none of the above - In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?
A. to reduce the magnetic hum and locking tendency of the rotor
B. to increase the tensile strength of the rotor bars
C. to ensure easy fabrication
D. none of the above - The torque of a rotor in an induction motor under running condition is maximum__________?
A. at the unit value of slip
B. at the zero value of slip
C. at the value of the slip which makes rotor reactance per phase equal to the resistance per phase
D. at the value of the slip which makes the rotor reactance half of the rotor - What will happen if the relative speed between the rotating flux of stator and rotor of the induction motor is zero ?
A. The slip of the motor will be 5%
B. The rotor will not run
C. The rotor will run at very high speed
D. The torque produced will be very large - Insertion of resistance in the rotor of an induction motor to develop a given torque?
A. decreases the rotor current
B. increases the rotor current
C. rotor current becomes zero
D. rotor current rernains same - The rotor of an induction motor runs at__________?
A. synchronous speed
B. below synchronous speed
C. above synchronous speed
D. any of the above - If a 3-phase supply is given to the stator and rotor is short circuited rotor will move___________?
A. in the opposite direction as the direction of the rotating field
B. in the same direction as the direction of the field
C. in any direction depending upon phase squence of supply
