Eddy Current Brakes Ppt Slides

7/25/2019 Eddy Current Brakes Ppt Slides

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Introduction of eddy current.

Introduction of eddy current brake.

Types of eddy current brake.

Circular eddy current brake.

Linear eddy current brake.

Working principle.

Advantages and Disadvantages.Application and future aspects.

conclusion

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When a magnetic core ( or conductor ) issubjected to a time varying magneticfield , voltages are induced in all possible

paths enclosing the flux.Voltage produces circulating currents in

the core. These currents are known aseddy currents.

These circulating eddies of currenthave inductance and thus inducemagnetic flux.

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It slows an object by creating eddy

currents .

Braking action is made by varying the

strength of the magnetic field.

Braking force depends on speed of

object.

A braking force is possible when electriccurrent is passed through the

electromagnets.

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Circular eddy current

brakes

Linear eddy current

brakes

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Brake assembly is circular in shape.

Consist of a disc (rotor) made up of

magnetic material.

Disc is placed between poles .

Conductor coils are wound on poles to

create magnetic field.

The movement of the disc through themagnetic field of the electromagnets

creates eddy currents in the discs.

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The principle of the linear eddy current

brake has been described by the French

physicist Foucault.

The linear eddy current brake consists of

a magnetic yoke with electrical coils

positioned along the rail.

This magnet does not touch the rail, but isheld at a constant small distance from the

rail (approximately 7 mm).

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Eddy current brake is based on two basiclaws of electromagnetics , which are

Faradays law

e = - d/dt

Lenz law :- An induced electromotiveforce (emf) always gives rise to a currentwhose magnetic field opposes theoriginal change in magnetic flux

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Magnetic field lines across the

magnetic material inside a copper tube

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Electromagnets produce magnetic field fromsupplied current .

Due to change in magnetic flux linkage(with

time) EMF is induced in conductor (disc).

EMF produces eddy currents in disc.

Eddy Currents produce another magnetic field

opposing the first field.

Opposing magnetic fields create force thatreduces velocity.

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16/26(Arrangement of ECB in high speed trains)

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FB

V =0 V>0

FNFA

Rail Flux lines

Pole core

coil

N S N

S

FA

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The braking energy of the vehicle is

converted in eddy current losses which

lead to a warming of the rail.Braking force is low at low speeds and

high at high speeds.

Copper and aluminum is used aswinding materials.

permanent magnets can be used

instead of electromagnets , thus notrequiring any power supply.

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No contact, therefore no wear or tear.No noise or smell.Adjustable brake force.

High brake forces at high speeds.It uses electromagnetic force instead of

friction.Can be activated at will via electrical

signal.Low maintenance.Light weight.

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Braking force diminishes as speed

diminishes.

no ability to hold the load in position at

standstill.

ECB is used with ordinary mechanical

brakes.

very tough design and simulation.

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In high speed trains.

In roller coaster for

braking and smooth

functioning.

It is also used in vehicles

but still not widely used.

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In future ordinary brakes will be

replaced by the ECB completely.

By the use of ECB in future we can control

high speed train completely.

By some new invention of extra

mechanism we can use ECB for slow

speed vehicles also.

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ECB is a good invention for the speed

control of high speed vehicles

We can control the speed of high speed

vehicles without wear and tear .

Drawback of ordinary mechanical

braking system can be overcome by

application of ECB.It makes use of opposing tendency

of eddy current.

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www.google.co.in

www.explainthatstuff.com/eddy-current-

brakes

www.wikipedia.org/wiki/Eddy_current_

brake/

www.wikipedia.org/wiki/Eddy_current

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Eddy Current Brakes Ppt Slides

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