1. In an induction motor, the value of average flux density in air gap should be small
a) to get good pf
b) to get poor pf
c) to achieve good efficiency
d) for minimum cost
ans. a
2. An increase in the value of air gap flux density in an induction motor
a) increase iron-loss
b) increase efficiency
c) decrease efficiency
d) both a and c are correct
ans. d
3. The pulsation losses and noise can be reduced in an induction motor by using
a) a large number of narrow slots
b) less number of narrow slots
c) large number of semi slots
d) none of these
ans. a
4. With increase in length of the air gap in an induction motor, the pulsation losses becomes
a) more
b) less
c) uncharged
d) none of these
ans. b
5. The large number of slots in an induction motor has
a) high over load capacity
b) low over load capacity
c) no effect no overload capacity
d) none of these
ans. a
6.A short air gap in an induction motor is necessary to achieve
a) to increased overload capacity
b) to reduce pulsation loss
c) to reduce the noise
d) a good pf
ans. d
7. The large value of air gap length in an induction motor results in
a) to increased overload capacity
b) to reduce pulsation loss
c) providing better cooling
d) reducing the noise
ans. a
8. In an induction motor , the motor fails to start when number of rotor slots is equal to number of stator slots this is known as
a) crawling
b) cogging
c) synchronous cusps
d) none of these
ans. b
9. The simplest way to eliminate the harmonic induction torques is
a) integral slot winding
b) skewing
c) chording
d) none of these
ans. c
10. The motor noise, vibrations, cogging and synchronous cusps can be reduced by
a) chording
b) integral slot winding
c) skewing
d) increasing the air gap length
ans. c
