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Electrical Engineering Objective Questions { Induction Motors }

99. For starting a Schrage motor, 3-phase supply is connected to
A. rotor via slip rings
B. regulating windings
C. secondary winding via brushes
D. stator as in an ordinary induction motor

100. The primary winding of Scharges motor is located
A. in stator
B. in lower part of rotor
C. in upper part of rotor partly in stator and partly in rotor

101.  When a stationary 3-phase induction motor is switched on with one phase disconnected
A. it will start but run very slowly
B. it will make jerky start with loud growling noise
C. remaining intact fuses will be blown out due to heavy rush of current
D. it is likely to burn out quickly unless immediately disconnected

102. The upper bars in a double squirrel cage induction motor have
A. low resistance and high reactance
B. high resistance and high reactance
C. high resistance and low reactance
D. low resistance and low reactance

103.  The pull-out torque for a normal squirrel cage induction motor usually occurs at a percentage slip of about
A. 1 0 to 15 per cent
B. 20 to 25 per cent
C. 35 to 45 per cent
D. 50 to 60 per cent

104. Speed variations of a squirrel cage induction motor are essentially similar to those of
A. D.C. shunt motor
B. D.C. series motor
C. synchronous motor
D. differential compound motor

105.  The difference between the synchronous speed and the actual speed of an induction motor is known as
A. lag
B. regulation
C. slip
D. back lash

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