Induction Motor

Where resistance is added in the rotor circuit of a slip ring induction motor

• A) The starting torque and current both reduce

• B) The starting torque and current both increase

• C) The starting current reduces but starting torque increase

• D) None of the above.

The starting torque of an induction motor is maximum when

• A) rotor resistance equals rotor reactance

• B) rotor resistance is twice the rotor reactance

• C) rotor resistance is 1/2 the rotor reactance.

• None of the above

The starting torque of a squirrel-cage induction motor is

• Full-load torque

• Slightly more than full-load torque

• Low

• Negligible

If any two phases for an induction motor are interchanged

• The motor will run in the reverse direction

• The motor will continue to run in the same direction

• The motor will stop

• The motor will Burn

The torque of an induction motor is

• Directly proportional to slip

• Inversely proportional to slip

• Proportional to the square of the slip

• None of the above

a cage rotor consists of

• laminated soft iron with copper or iron end rings

• laminated soft iron core containing longitudinal copper or iron bars which are capped at each end via a shorting plate.

• laminated silica steel core containing longitudinal copper bars shorted at one end only

• laminated soft iron core with three phase star connected windings and slip rings,

An induction motor is identical to

• D.C. compound motor

• D.C. series motor

• Synchronous motor

• Transformer with secondary short circuited

Which of the following motor has high starting torque?

• Slip ring Induction motor

• Squirrel cage Induction motor

The maximum EMF is induced in the rotor of a 3-phase induction motor when it

• No-load

• Full-load

• Half-load

• rotor is blocked

a rotating magnetic field is created by :

• applying three phase waveforms to rotor winding placed 120 degrees apart.

• applying three phase line voltages to stator winding via sliprings

• applying three phase line voltages to red yellow and blue stator windings.

• applying three phase phase voltages to a delta connected load.