This document presents a summary of eddy current brakes. It begins with an introduction explaining that eddy current brakes use kinetic energy dissipation through heat to slow or stop moving objects, without friction. It then covers the principles of electromagnetic induction and Lenz's law. The document describes circular and linear eddy current brake types, and explains their working mechanism where eddy currents in a conductive material interact with a magnetic field to generate braking forces. Advantages include being non-mechanical, fully resettable and able to brake at any speed. Disadvantages are limited braking at low speeds and inability to hold stationary loads. Applications include additional safety braking for trains and vehicles.

1. A PRESENTATION ON “EDDY
CURRENT BRAKES”
2020-2021
presented by:
DIPENDRA SINGH
7th Sem, 4th Year
DEPARATMENT OF ELECTRICAL ENGINEERING
ENGINEERING COLLEGE JHALWAR
RAJASTHAN TECHNICAL UNIVERSITY , KOTA

2. CONTENTS
Introduction
Principle
Types of Eddy Current Brakes
Working
Advantages
Disadvantages
Applications

3. INTRODUCTION
An eddy current brake, like a conventional friction brake, is a device used
to slow or stop a moving object by dissipating its kinetic energy as heat.
These brakes make use of opposing tendency of eddy currents.
In an eddy current brake the magnetic field may be created by a
permanent magnet, or an electromagnet so the braking force can be
turned on and off or varied by varying the electric current in the
electromagnet's windings.

4.  The Eddy Current brakes does not work by friction, there are no brake
shoe surfaces to wear out, necessitating replacement, as with friction
brakes.
 Eddy current brakes are used to slow high-speed trains and roller
coasters, to stop powered tools quickly when power is turned off, and
in electric meters used by electric utilities.

5. PRINCIPLE
 Faraday’s Law of Electromagnetic Induction
The induced electromotive force at any closed circuit is equal to the negative
of the time rate of change of the magnetic flux through the circuit.
Where
• E is EMF
• ΦB is Magnetic flux
• N is Number of turns of wire
E= -N dΦB/dt

6.  Lenz’s Law
An induced emf always gives rise to a current whose magnetic field opposite the
change in magnetic flux.
Where
• E is EMF
• ΦB is Magnetic Flux
E= -dΦB/dt

7. TYPES
 Circular:-In a circular eddy current brakes, the
conductor is a flat disk rotor that turns between the
poles of the magnet.

8.  Linear :- In a linear eddy current brakes, the conductive piece
is a straight rail or track that the magnet moves along.

9. WORKING
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
Contd..,

10. generated inside the copper which would their own magnetic field.
 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.

11. ADVANTAGES
It uses electromagnetic force and not mechanical friction.
Non-mechanical ( no moving parts, no friction )
Fully resettable
Can be activated at will via electrical signal
Low maintenance
Operates at any rotational speed
Light weight
Eddy-current brakes are quite, frictionless, and wear-free, and require
little or no maintenance.
They produce no smell or pollution ( unlike friction brakes, which can
release toxic chemicals into the environment ).

12. DISADVANTAGES
 Braking force diminishes as speed diminishes with no ability
to hold the load in position at standstill.
 That could be considered to be a safety issue, but it really
means that friction braking may need to be used as well.
 Eddy-current brakes can only be used where the
infrastructure has been modified to accept them.
 It can not be used at low speed vehicles or vehicle running at
low speed

13. APPLICATIONS
 For additional safety on long decants in mountain area.
 For high speed passenger and goods vehicle.
 Eddy current brakes are best substitutes for ordinary brakes,
which are being used nowadays in road vehicles even in
trains, because of their jerk-free operation.
 In mountain areas where continuous braking force is needed,
for a long time, the eddy current braking is very much useful
for working without overheating.
 Eddy current brakes are very much useful for high-speed
passengers and good vehicles.

14. CONCLUSION
 The ordinary brakes which are being used now a days stop
the vehicles by means of mechanical blocking. These may
cause skidding and wear and tear of the vehicle.
 Eddy Current Brakes is a good invention for speed control of
high speed vehicles.
 It is an abrasion free method for braking of vehicle including
trains.
 It makes use of opposite tendency of eddy currents.

15. THANK YOU