This document is a seminar presentation on eddy current brakes given by M.Sushmitha. It defines eddy current brakes as magnetic devices that use a stationary magnetic field and a solid rotating metal disc to generate resistance and braking force. The presentation covers the components, principles of operation, types including circular and linear brakes, advantages like contactless braking and applications in trains. It notes that eddy current brakes can control speed without wear but have limitations at low speeds. The presentation provides an overview of eddy current brakes for educational purposes.

1. A Seminar Presentation
On
EDDY CURRENT BRAKES
by
M.SUSHMITHA 14121A02C3
under the guidance of
Mr. K. Leleedhar Rao M.Tech.
Assistant professor
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
SREE VIDYANIKETHAN ENGINEERING COLLEGE
A.RANGAMPET, TIRUPATI – 517 102
INDIA
2017 - 2018

2. Contents:
 Objective
 Eddy current braking
 Components and operational features of ECB
 Types of eddy current brakes
 Working of ECB
 Advantages
 Disadvantages
 Applications
 Future Aspects
 conclusion
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3. Objective:
 To provide an abrasion free method for braking of vehicles including
trains.
 To control the speed of high speed vehicles without wear and tear in
parts of it.
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4. Introduction to eddy current:
 Eddy current is the swirling
current produced in a conductor
which is subjected to change in
magnetic field.
 Because of the tendency of the
eddy current to oppose, it
causes energy to be lost.
 More accurately it converts more
useful energy, such as kinetic
energy in to heat.
 Practically its not desirable
Fig.1.Eddy currents
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5. Eddy current braking:
• These are simple magnetic devices that
consists of non ferromagnetic conductor
that moves through a magnetic field.
• An example is shown in fig. where
magnetic field is created in the gap of a
torroidal magnet with diameter =D
• When a conductive disc rotates eddy
current is induced at a average distance
R from axis of rotation. Fig.2.Eddy current brakes
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6. Principle of operation :
• It works according to faraday’s law of electromagnetic induction.
• According to this law when ever a conductor cuts magnetic lines of forces a
emf is induced in it.
• emf. Magnitude α strength of magnetic field
• α speed of the conductor
• According to lenz’s law the direction of current is in such a way that it
opposes the very cause producing it i.e movement of the disc.
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7. Components and Operational features of
Eddy Current Brakes
• Electromagnets
• Cast Iron Core
• Conducting (Copper) Wire
• Mounting bolts
• Disc
• Mild steel machined from plates
Essentially the eddy current brake consists of two parts, a stationary
magnetic field system and a solid rotating part, which include a
metal disc.
These two parts are separated by a short air gap, they're being no
contact between the two for the purpose of torque transmission.
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8. Contd..
• Stator consists of pole core, pole shoe, and field winding.
• The field winding is wounded on the pole core.
• Pole core and pole shoes are made of cast steel laminations and
fixed to the state of frames by means of screw or bolts.
• Copper and aluminum is used as winding materials.
During braking, the metal disc is exposed to a magnetic field from an
electromagnet, generating eddy currents in the disc. The magnetic
interaction between the applied field and the eddy currents slow down
the rotating disc. Thus the wheels of the vehicle also slow down since
the wheels are directly coupled to the disc of the eddy current brake,
thus producing smooth stopping motion.
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9. Circular eddy current brake system:
• Non-ferromagnetic metal discs (rotors) are connected to a rotating coil,
and a magnetic field between the rotor and the coil creates a resistance
used to generate electricity or heat.
• When electromagnets are used, control of the braking action is made
possible by varying the strength of the magnetic field.
• A braking force is possible when electric current is passed through the
electromagnets.
• The movement of the metal through the magnetic field of the
electromagnets creates eddy currents in the discs.
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10. 10
Fig.3.Circular eddy current brake

11. Linear eddy current brake:
• The linear eddy current brake consists of a magnetic yoke with
electrical coils positioned along the rail, which are being
magnetized alternating as south and north magnetic poles.
• This magnet does not touch the rail, as with the magnetic brake, but
is held at a constant small distance from the rail (approximately
seven mm).
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12. Contd…
• When the magnet is moved along the rail, it generates a non-
stationary magnetic field in the head of the rail, which then
generates electrical tension (Faraday's induction law), and causes
eddy currents.
• These disturb the magnetic field in such a way that the magnetic
force is diverted to the opposite of the direction of the movement,
thus creating a horizontal force component, which works against the
movement of the magnet.
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13. Contd…
• The braking energy of the vehicle is converted in eddy current
losses which lead to a warming of the rail. (The regular
magnetic brake, in wide use in railways, exerts its braking force
by friction with the rail, which also creates heat.)
.
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14. Fig.4.Linear current brake
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15. Working of eddy current brake:
•Suppose we have a huge solid block of copper mounted on wheels. It is
moving at a very high speed and we need to stop it.
•Suppose we place a giant magnet next to the track so that train had to
pass nearby.
•As the copper approached the magnet eddy currents would be generated
inside the copper which would their own magnetic field.
Fig.5.Railroad train
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16. Contd…
• As the front part approached the magnet eddy currents in that bit of
copper would try to generate a repulsive magnetic field to slow down
copper’s approach to magnet.
• As the front passed by, slowing down, the currents there would
• reverse, generating an attractive magnetic field that tried to pull the
• train back again. (again, slowing it down).
• The copper would heat up the eddy currents swirled inside
• it, gaining the kinetic energy lost by the train as it slowed down.
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17. Advantages:
• Independent of wheel/rail adhesion.
• No contact, therefore no wear or tear.
• No noise or smell.
• Adjustable brake force.
• High brake forces at high speeds.
• Also used as service brake.
• It uses electromagnetic force and not friction Non-mechanical
(no moving parts, no friction)
• Can be activated at will via electrical signal
• Low maintenance
• Light weight
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18. Disadvantages:
• Braking force diminishes as speed diminishes with no ability to
hold the load in position at standstill.
• It can not be used at low speed vehicles or vehicle running at low
speed.
• ECB is used with ordinary mechanical brakes.
• Nowadays ECB is using only for safety purpose.
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19. Applications:
• It is used as a stopping mechanism in trains.
• It is also used in the smooth braking and functioning of roller
coasters and such fast moving machines.
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20. Future aspects:
• In future ordinary brakes will be replaced by the ECB completely.
• By the use of ECB in future, we can control the high speed train
completely.
• By some invention of extra mechanism we can use ECB for slow
speed vechicles also.
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21. Conclusion:
• 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 in parts of it.
• 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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22. References:
[1] Manuel I Gonz´alez, “Experiments with eddy currents: the eddy current brake, European
journal of physics, PP. 464-468, Published 20 April 2004.
[2] B. Ebrahimi, “Development of hybrid electromagnetic dampers for vehicle suspension
systems, Ph.D. dissertation, Dept. Mech. Eng., Univ. of Waterloo, Waterloo, ON, USA, 2009.
.[3] P. J. Wang and S. J. Chiueh, “Analysis of eddy-current brakes for high speed railway,”IEEE
Trans.Magn., vol. 34, no. 4, pp. 1237–1239, Jul. 1998.
[4] Der-Ming Ma, Jaw-Kuen Shiau, “THE DESIGN OF EDDY-CURRENT MAGNET BRAKES,”
Transactions of the Canadian Society for Mechanical Engineering, Vol. 35, No. 1, 2011.
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