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Speed Control of Three Phase Induction Motor

A three phase induction motor is basically a constant speed motor so it’s somewhat difficult to control its speed. The speed control of induction motor is done at the cost of decrease in efficiency and low electrical power factor. Before discussing the methods to control the speed of three phase induction motor one should know the basic formulas of speed and torque of three phase induction motor as the methods of speed control depends upon these formulas.

Synchronous Speed

Where, f = frequency and P is the number of poles

The speed of induction motor is given by, Where, N is the speed of the rotor of an induction motor, Ns is the synchronous speed, S is the slip. The torque produced by three phase induction motor is given by,

When the rotor is at standstill slip, s is one. So the equation of torque is, Where, E2 is the rotor emf Ns is the synchronous speed R2 is the rotor resistance X2 is the rotor inductive reactance

The Speed of Induction Motor is changed from Both Stator and Rotor Side. The speed control of three phase induction motor from stator side are further classified as :

The speed controls of three phase induction motor from rotor side are further classified as:

Speed Control from Stator Side

Speed Control from Rotor Side



NNAVEED commented on 18/05/2018
Nice explanation and easy language to understand and required inforinformation is available over all osm i hope I will get more information about different topics
SSUMIT JAIN commented on 14/05/2018
sir,how rotor resistance increase or decrease by injecting EMF in rotor side
GGURUSAMY commented on 30/04/2018
very useful thank you
NNAVEEN KUMAR commented on 08/03/2018
This matter is more than enough.
Comments

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