Polyphase Induction Motors MCQ - Electrician (Set-1) with Answers

Polyphase Induction Motors MCQ - Electrician (Set-1) with Answers

71) It is advisable to avoid direct on line starting of induction motor having a capacity of more than 3 HP because

Answer is:

the motor takes five to seven times of its full load current

72) On switching ON the starter the magnetic contactor vibrates heavily, the causes may be

Answer is:

low voltage and dirt on the armature contact surface

73) in the manual star delta starter, the stop button connection is in series with the

Answer is:

overload relay contacts

74) You are working with a fully automatic star delta starter. You notice that when start switch is pressed the motor starts in star, but does not change to delta. In the above case the trouble will be in

Answer is:

timer and its circuit

75) Rotor resistance starters are used with wound rotor induction motor. When the motor is running the resistance in starter are

Answer is:

shorted

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