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.Management Sciences
Category: Polyphase Induction Motors
Short-circuit test on an induction motor cannot be used to determine___________?
A. windage losses
B. copper losses
C. transformation ratio
D. power scale of circle diagram
The number of slip rings on a squirrel cage induction motor is usually____________?
A. two
B. three
C. four
D. none
The ‘crawling” in an induction motor is caused by___________?
A. high loads
B. low voltage supply
C. improper design of machine
D. harmonics developed in the motor
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
The crawling in the induction motor is caused by____________?
A. low voltage supply
B. high loads
C. harmonics develped in the motor
D. improper design of the machine
E. none of the above
A pump induction motor is switched on to a supply 30% lower than its rated voltage. The pump runs. What will eventually happen ? It will____________?
A. stall after sometime
B. stall immediately
C. continue to run at lower speed without damage
D. get heated and subsequently get damaged
In case of a double cage induction motor, the inner cage has__________?
A. high inductance arid low resistance
B. low inductance and high resistance
C. low inductance and low resistance
D. high inductance and high resistance
Which type of bearing is provided in small induction motors to support the rotor shaft ?
A. Ball bearings
B. Cast iron bearings
C. Bush bearings
D. None of the above
An induction motor with 1000 r.p.m. speed will have____________?
A. 8 poles
B. 6 poles
C. 4 poles
D. 2 poles
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