× Home MCQ Videos Basic Electrical Circuit Theories Electrical Laws Materials Batteries Illumination Generation Transmission Distribution Switchgear Protection Measurement Control System Utilities Safety Transformer Motor Generator Electrical Drives Electronics Devices Power Electronics Digital Electronics Biomedical Instrumentation

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,

You may also be interested on
Speed Control of Three Phase Induction Motor

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


EEDAPAL OTOTIN commented on 17/07/2018
So nice.
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


New Articles
Electroencephalography | EEGECG Recording SetupElectrocardiographyECG Lead SystemBiological Amplifiers
Articles on Three Phase Induction Motor
Working of 3 Phase IMConstruction of 3 Phase IMTypes of 3 Phase IMSquirrel Cage Induction MotorClassification of Squirrel Cage IMDeep Bar IMInduction Motor RotorSpeed Control of 3 Phase IMSpeed Control of Induction MotorTorque in 3 Phase IMStarting Methods for Polyphase IMStarting of 3 Phase IMDOL StarterStar Delta Starter
More Articles on Electric Motor
Basic MotorDC Motor BasicDC Motor TypesBasic Induction MotorSynchronous Motor
Articles Categories
MCQ Videos Basic Electrical Circuit Theories Electrical Laws Materials Batteries Illumination Generation Transmission Distribution Switchgear Protection Measurement Biomedical Instrumentation Control System Utilities Safety Transformer Motor Generator Electrical Drives Electronics Devices Power Electronics Digital Electronics Guest Post