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 Pediain.com
When a magnetic core ( or conductor ) is subjected to a time varying magnetic field , voltages are induced in all possible paths enclosing the flux. Voltage produces circulating currents in the core. These currents are known as eddy currents. These circulating eddies of current have inductance and thus induce magnetic 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 electric current is ed through the electromagnets. Pediain.com
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 the magnetic field of the electromagnets creates eddy currents in the discs. Pediain.com
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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 is held at a constant small distance from the rail (approximately 7 mm). Pediain.com
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Eddy
current brake is based on two basic laws of electromagnetics , which are Faraday’s law
e = - d/dt Lenz
law :- “An induced electromotive force (emf) always gives rise to a current whose magnetic field opposes the original change in magnetic flux” Pediain.com
Magnetic field lines across the magnetic material inside a copper tube
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Electromagnets produce magnetic field from supplied 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 that reduces velocity. Pediain.com
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(Arrangement of ECB in high speed trains) Pediain.com
V =0
V>0
Pole core
coil
N F Rail
S
S
N
F
F
A
F
B
N
A
Flux lines Pediain.com
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 as winding materials. permanent magnets can be used instead of electromagnets , thus not requiring any power supply.
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No
, 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. Pediain.com
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. Pediain.com
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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