Induction Machine - Electrical Engineering - Lecture Slides, Slides of Electrical Engineering

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^ Induction Motor Construction ^ Basic Induction Motor Concepts ^ The Equivalent Circuit of an Induction Motor. ^ Power and Torque in Induction Motor. ^ Induction Motor Torque-Speed Characteristics ^ Variations in Induction Motor Toque-SpeedCharacteristics ^ Starting of Induction Motors ^ Speed Control of Induction Motor ^ Some important features of IM

Asynchronousmachines are thosemachines which donot run atsynchronous speed.

Most AC motors areinduction motors.Induction motors arefavored due to theirruggedness andsimplicity. In fact, 90%of industrial motorsare induction motors.

By induction motor,we mean that thestator windingsinduces a currentwhich flow in the rotorconductors, like atransformer.

^ Induction motors are used worldwide in manyresidential, commercial, industrial, and utilityapplications. ^ Induction Motors transform electrical energy intomechanical energy. ^ It can be part of a pump or fan, or connected tosome other form of mechanical equipment suchas a winder, conveyor, or mixer.

With rotary orlinear motionThree phasesupply or single-phase supplyWith wound orcage rotor

^ The three basic parts of an AC motor are the rotor,stator, and enclosure. ^ The stator and the rotor are electrical circuits thatperform as electromagnets.

^ The rotor is the rotating part of theelectromagnetic circuit. ^ It can be found in two types:^ ◦^ Squirrel cage^ ◦^ Wound rotor ^ However, the most common type of rotor isthe “squirrel cage” rotor.

^ Induction motor types:^ ^ Squirrel cage type:^ Rotor winding is composed of copper bars embedded inthe rotor slots and shorted at both end by end rings^ Simple, low cost, robust, low maintenance^ ^ Wound rotor type:^ Rotor winding is wound by wires. The winding terminalscan be connected to external circuits through slip ringsand brushes.^ Easy to control speed, more expensive.

^ Stator core :- The stator core is assembledof^ high

grade, low^ electrical

loss,^ silicon

steel punching.^ oThe thickness varies from 0.35 mm to 0.7mm.^ oThe laminations are used to reduce eddycurrent loss.^ oThe laminations are slotted on the innerperiphery

and^ are

insulated

from^

each

other. The insulated stator conductors areplaced in these slots.

^ Stator or field winding:-The^

stators^

conductors

are^ connected

to

form^ a^

three^ phase

winding.

The^ three

phases of the winding can be connected ineither star or delta.