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Eddy Current Brakes PPT









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1. Eddy Current Brakes

2.  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

3.  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.

4.  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 passed through the electromagnets.

5.  Circular eddy current brakes
 Linear eddy current brakes

6.  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.

7.  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).

8.  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"

9. Magnetic field lines across the magnetic material inside a copper tube

10.  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.

11. Magnetic field lines across the magnetic material inside a copper tube

12. Falling Magnet

13. 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.

14. Copper tube, Secondary magnetic Field, Primary magnetic Field

15. Original B oppposing B

16. (Arrangement of ECB in high speed trains)

17. V =0 Pole core
V>0 Rail Flux lines

18.  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.

19.  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.

20.  Braking force diminishes as speed diminishes.
 no ability to hold the load in position at standstill.
 ECB is used with ordinary mechanical rakes.
 very tough design and simulation.

21.  In high speed trains.  In roller coaster for braking and smooth functioning.
 It is also used in vehicles but still not widely used.

22.  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.

23.  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.

24.  www.google.co.in
 www.explainthatstuff.com/eddy-current-brakes
 www.wikipedia.org/wiki/Eddy_current_brake/
 www.wikipedia.org/wiki/Eddy_current

25. Thank you

26. Your Queries Please


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