Electrical Machines Questions and Answers – Induction Machines
Starting of Polyphase Induction Motors Questions
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The method which employs reduction of the voltage while induction motor starting is/are
A. DOL starting
B. Auto transformer starting
A. DOL starting
B. Auto transformer starting
Correct!
Wrong!

Voltage induce in the induction motor is highest at
Correct!
Wrong!

Series reactor method of starting has main disadvantage of lowering the starting power. This can be overcome by
Correct!
Wrong!

A 3phase, 4pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by auto transformer method of starting with a tapping ratio of ‘x’, then the
starting torque will be
starting torque will be
Correct!
Wrong!

Starting methods applicable to both squirrelcage and slip ring induction motors is/are
A. DOL starting
B. Auto transformer starting
C. Rotor resistance starting
A. DOL starting
B. Auto transformer starting
C. Rotor resistance starting
Correct!
Wrong!

The method which employs raising of the voltage while induction motor starting is/are
A. DOL starting
B. Auto transformer starting
A. DOL starting
B. Auto transformer starting
Correct!
Wrong!

Starters are required in the induction motor because
Correct!
Wrong!

Full voltage starting of induction motor may cause
Correct!
Wrong!

For a 4pole, 50 Hz induction motor has starting current as 5 times to that of the full load current working at a speed of 1450rpm.
The ratio of starting to full load torque will be
The ratio of starting to full load torque will be
Correct!
Wrong!

For the application requiring high starting torque and minimum starting current, the most suitable starting method will be
Correct!
Wrong!

A 3phase, 4pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by auto transformer method of starting with a tapping ratio of ‘x’, then the
starting current reduces by
starting current reduces by
Correct!
Wrong!

Auto transformer method of starting has most acceptable method for the starting of the induction motor due to
Correct!
Wrong!

Series reactor method of starting has main disadvantage of
Correct!
Wrong!

External methods of induction motor starting is employed to
Correct!
Wrong!

A 3phase, 4pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by reactance method of starting with a fraction of ‘x’, then the starting torque reduces by
Correct!
Wrong!

A 3phase, 4pole, 50 Hz induction motor is uses DOL method of starting. It is later replaced by reactance method of starting with a fraction of ‘x’, then the starting current reduces by
Correct!
Wrong!
