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Name of Institution

Amity School of Engineering & Technology

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Electrical Machines BTM405

Sudhanshu Singh

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Name of Institution

Introduction

Three phase induction motor

Construction

Principle operation

Slip concept

Induction Motor as transformer Characteristics

Equivalent circuit

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Name of InstitutionIntroduction

The poly phase induction machine is by aconsiderable margin, most widely used AC

motor.Reason: low cost, simple, rugged construction,

good operating characteristics .

The induction motor is called asynchronousmachine. It can never run at synchronous

speed. Like other electrical machines it isreversible means it can operate as generatorand motor both.

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Name of InstitutionThree phase Induction Motor

most common and frequently encountered machines in

industries.* wide range of power ratings: fractional

horsepower to 10 MW

* -

to full load

* speed depends on the frequency of the power

source

not easy to have variable speed control

requires a variable-frequency power-electronicdrive for optimal speed control

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Name of InstitutionConstruction

An induction motor has two main parts

a stationary stator

consisting of a steel frame that supportsw

core, constructed from stacked

laminations , having a number of evenlyspaced slots, providing the space for

the stator winding

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Name of InstitutionConstruction

a revolving rotor

composed of punched laminations, stacked tocreate a series of rotor slots, providing spacefor the rotor winding

conventional 3-phase windings made ofinsulated wire (wound-rotor) similar to the

winding on the stator

aluminum bus bars shorted together at theends by two aluminum rings, forming asquirrel-cage shaped circuit (squirrel-cage)

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Name of InstitutionRotating Magnetic Field

Balanced three phase windings, i.e.

mechanically displaced 120 degrees formeach other, fed by balanced three phase

source

A rotating magnetic field with constantmagnitude is produced, rotating with a speed

nsync = 120*fe / P rpm

where fe is the supply frequencyand P is the no. of poles and nsync is called

the synchronous speed in rpm

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Name of InstitutionRotating Magnetic Field

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