Speed Control of 3-Phase Wound Rotor Induction Motor (Experiment No. 06) | Electrical Engineering

Описание: When a 3-phase AC power supply, is connected to the stator terminals of an induction motor, 3-phase alternating currents flow in the stator windings.

These currents set up a changing magnetic field (flux pattern), which rotates around the inside of the stator.

The speed of rotation is in synchronism with the electric power frequency and is called the synchronous speed.

In the simplest type of 3-phase induction motor, the rotating field is produced by 3 fixed stator windings, spaced 120o apart around the perimeter of the stator.

When the three stator windings are connected to the 3-phases power supply, the flux completes one rotation for every cycle of the supply voltage.

Speed control by Rotor resistance control:

As the name implies, this type of control is only possible with wound rotor induction motors i.e. this method cannot be applied to the squirrel cage induction motor.

Wound rotor induction motors are usually started by connecting staring resistance in the secondary circuit which are shorted out as the motor speeds up.

This method of speed control has similar characteristics to those DC shunt motor speed control by means of resistance in series with the armature.