In medium sized induction motors, the slip is generally around___________?
(A) 0.04%
(B) 0.4%
(C) 4%
(D) 14%
Which of the following component is usually fabricated out of silicon steel ?
(A) Bearings
(B) Shaft
(C) Statorcore
(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
The number of slip rings on a squirrel cage induction motor is usually____________?
(A) two
(B) three
(C) four
(D) none
The efficiency of an induction motor can be expected to be nearly____________?
(A) 60 to 90%
(B) 80 to 90%
(C) 95 to 98%
(D) 99%
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 case the air gap in an induction motor is increased?
(A) the magnetising current of the rotor will decrease
(B) the power factor will decrease
(C) speed of motor will increase
(D) the windage losses will increase
In an induction motor, no-load the slip is generally____________?
(A) less than 1%
(B) 1.5%
(C) 2%
(D) 4%
The injected e.m.f. in the rotor of induction motor must have__________?
(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
In case of the induction motors the torque is___________?
(A) inversely proportional to (Vslip)
(B) directly proportional to (slip)2
(C) inversely proportional to slip
(D) directly proportional to slip