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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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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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