Electrical Machines Questions and Answers – Induction Machines
Rotor Frequency in Induction Motors
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A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the stator filed with respect to stator structure is
Correct!
Wrong!

In a three phase slip ring induction motor, brushes are connected to
Correct!
Wrong!

A properly shunted center zero galvanometer is connected in the rotor circuit of a 6pole, 50 hz wound rotor induction motor. If the makes 90 complete oscillations in one minute, the rotor speed is
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the rotor field w.r.t. stator field is
Correct!
Wrong!

The rotor of th 3phase induction motor rotates in the same direction as that of stator field. This can be explained by
Correct!
Wrong!

A 4pole, 3phase slip ring induction motor is used as a frequency changer. Its stator is excited from 3phase, 50 Hz supply. A load requiring 3phase, 20 Hz supply is connected to the starconnected rotor through three sliprings of SRIM.
At what two speeds the prime mover should drive the rotor of this SRIM?
At what two speeds the prime mover should drive the rotor of this SRIM?
Correct!
Wrong!

For a 4 pole three phase induction motor having synchronous speed of 1500 rpm is operating at 1450rpm. The frequency of the induced emf in rotor is
Correct!
Wrong!

The rotor winding for 3phase slip ring induction motor having delta connected stator must be connected in
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Rotor frequency is
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. The full load slip will be
Correct!
Wrong!

The 3phase induction motor with rotor circuit open will
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. The number of poles of this motor is
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the rotor field w.r.t. rotor structure is
Correct!
Wrong!

Stator flux induces emf in the rotor conductors
Correct!
Wrong!

Slip is defined as (Ns as the synchronous speed and Nr is the rotor speed)
Correct!
Wrong!

The squirrel cage induction motor of 6pole can be used as ________ induction motor.
Correct!
Wrong!

A three phase, 50 Hz induction motor has a full load speed of 1440 rpm. Speed of the stator field revolving rotor structure is
Correct!
Wrong!

For a 4pole, 3phase induction motor the rotor speed found is 2100 rpm at 50 Hz. Then the phase sequence of the emf generated will be
Correct!
Wrong!
