991. The torque developed in the cage induction motor with autostarter is___________?
A. k/torque with direct switching
B. K x torque with direct switching
C. K2 x torque with direct switching
D. k2/torque with direct switching
992. It is advisable to avoid line-starting of induction motor and use starter because__________?
A. motor takes five to seven times its full load current
B. it will pick-up very high speed and may go out of step
C. it will run in reverse direction
D. starting torque is very high
993. Stepless speed control of induction motor is possible by which of the following methods ?
A. e.m.f. injection in rotor eueuit
B. Changing the number of poles
C. Cascade operation
D. None of the above
994. For which motor the speed can be controlled from rotor side ?
A. Squirrel-cage induction motor
B. Slip-ring induction motor
C. Both A. and (b)
D. None of the above
995. 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
996. In Ns is the synchronous speed and s the slip, then actual running speed of an induction motor will be___________?
A. Ns
B. s.N,
C. (l-s)Ns
D. (Ns-l)s
997. 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
998. 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
999. 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
1000. Which of the following component is usually fabricated out of silicon steel ?
A. Bearings
B. Shaft
C. Statorcore
D. None of the above