1. An Induction motor is said to be crawling when:
a) it runs at one-seventh if the rated speed
b) it accelerates too fast
c) oscillation of rotor
d) magnetic locking of rotor and stator
2. Circle diagram of an induction motor can be used to determine the:
a) power factor
b) efficiency
c) slip
d) all the above
3. Air gap of a 3 phase induction motor is kept small to:
a) reduce the possiblity of the crawling
b) reduce the noise
c) reduce the magnetizing current
d) obtain high starting torque
4. The power factor of an induction motor at full load is likely to be:
a) unity
b) 0.85 lag
c) 0.85 lead
d) 0.5 lag
5. The no load current of the induction motor is approximately __ percentage of the full load current:
a) 2
b) 10
c) 30
d) 60
6. Iron loss in 3 phase induction motor is negligible. This is due to:
a) very low frequency of emf induced in the rotor
b) very low induced emf is induced in the rotor
c) very low flux density in rotor parts
d) constant magnitude of the flux linking the rotor core
7. Presence of 5th harmonics in induction motor causes:
a) cogging
b) crawling
c) small reverse braking torque
d) hunting
8. The rotor slots in 3 phase induction motor are kept inclined. This phenonmenon is known as:
a) skewing
b) crawling
c) cogging
d) none of the above
9. In squirrel cage induction motor high starting torque is achieved by using:
a) high resistance in series with the rotor circuit
b) low resistance across rotor circuit
c) double cage rotor
d) none of the above
10. In a 3 phase induction motor, the stator slots are:
a) equal to rotor slots
b) exact multiple of rotor slots
c) should not be exact multiple of rotor slots
d) none of the above
a) it runs at one-seventh if the rated speed
b) it accelerates too fast
c) oscillation of rotor
d) magnetic locking of rotor and stator
2. Circle diagram of an induction motor can be used to determine the:
a) power factor
b) efficiency
c) slip
d) all the above
3. Air gap of a 3 phase induction motor is kept small to:
a) reduce the possiblity of the crawling
b) reduce the noise
c) reduce the magnetizing current
d) obtain high starting torque
4. The power factor of an induction motor at full load is likely to be:
a) unity
b) 0.85 lag
c) 0.85 lead
d) 0.5 lag
5. The no load current of the induction motor is approximately __ percentage of the full load current:
a) 2
b) 10
c) 30
d) 60
6. Iron loss in 3 phase induction motor is negligible. This is due to:
a) very low frequency of emf induced in the rotor
b) very low induced emf is induced in the rotor
c) very low flux density in rotor parts
d) constant magnitude of the flux linking the rotor core
7. Presence of 5th harmonics in induction motor causes:
a) cogging
b) crawling
c) small reverse braking torque
d) hunting
8. The rotor slots in 3 phase induction motor are kept inclined. This phenonmenon is known as:
a) skewing
b) crawling
c) cogging
d) none of the above
9. In squirrel cage induction motor high starting torque is achieved by using:
a) high resistance in series with the rotor circuit
b) low resistance across rotor circuit
c) double cage rotor
d) none of the above
10. In a 3 phase induction motor, the stator slots are:
a) equal to rotor slots
b) exact multiple of rotor slots
c) should not be exact multiple of rotor slots
d) none of the above
