This document presents information on eddy current brakes. It discusses the theory of operation, explaining that an eddy current is induced in a conductor by a changing magnetic field, which then creates its own opposing magnetic field. It describes the construction of eddy current brakes, which have a stationary electromagnet and a rotating metal disc, with no contact between the parts. When current is applied to the electromagnet, eddy currents in the disc generate drag to slow its rotation. The document classifies eddy current brakes and lists their advantages like contactless braking and disadvantages like inability to hold at zero speed. It provides examples of applications in trains and rollercoasters.

1. Presented By:
Ashutosh Polakhare
Seat No. T120212551
AISSMS COLLEGE OF ENGINEERING
Department of Electrical Engineering
Guided By:
Mrs. V.N.Tarange

2. Contents
 Introduction
 Theory Of Operation
 Constructional Details
 Working Principle
 Classification of eddy current brakes
 Advantages & Limitations
 Applications
 Conclusion

4. Introduction
 Eddy current is a swirling current
set up in a conductor in response to
a changing magnetic field.
 By Lenz's law, the current swirls in
such a way as to create a magnetic
field opposing the change
 It slow an object by creating eddy
currents through electromagnetic
induction which create resistance,
and in turn either heat or electricity.

5. Introduction(continued…)
 Braking action is made by varying the strength of the
magnetic field by means of control switch.

6. Constructional Details
 Components:-
1. Electromagnets(stationary)
 Cast Iron Core
 Conducting (Copper) Wire
 Mounting bolts
2. Disc(rotator)
 Mild steel
 Machined from plates
FVLHSV

7.  It consists of two members, a stationary magnetic field system
and a solid rotary member, generally of mild steel.
 Two members are separated by a short air gap, they're being no
contact between the two for the purpose of torque transmission.
 Stator consists of pole core, pole shoe, and field winding.
 Pole core and pole shoes are made of cast steel and fixed to the
state of frames by means of screw, bolts, rivets.
 Max. diameter: 1.The spacing of vehicle chassis frame
2.Vehicle floor clearance

8. Principle involved

9. Theory of operation
 Induced EMF is proportional to
the strength of magnetic field &
speed of conductor.
 The direction of the current is in
such a way as to oppose the cause,
i.e. movement of the disc.

10. Working Principle
 Electromagnets produce magnetic field from supplied
current.
 Change of magnetic flux (with time) induces eddy
currents in conductor (disc)

11.  Eddy Currents produce
another magnetic field
opposing first field.
 Opposing magnetic fields
create force that reduces
velocity
 A control switch is put on
which is placed on the
steering column in a
position for easy
operation.

12. Classification of ECB
1) Electrically excited eddy current
brakes i.e., by Electromagnets
2) Permanent magnet eddy current
brakes

13. Electrically excited eddy current brakes
 It consists of a magnetic yoke with electrical coils which are being magnetized
alternately with current .
 When the magnet is moved along the rail, it generates a non-stationary
magnetic field which generates electrical tension 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.
 The braking energy of the vehicle is converted in eddy current losses which
lead to a warming of the rail.

14. Permanent magnet eddy current brakes
 Permanent magnet ECB are a simple
& reliable alternative to mechanical
& electromagnetic brakes.
 These brakes need a mechanical
actuator to turn the magnets in an on
and off position.
 Permanent ECB have been developed
for subways, trams and local trains.
 The main advantage of this type of
brake is safety i.e., it does not need
electrical power supply to energize
the magnet.

15. 1) It uses electromagnetic force and not friction.
2) No contact, therefore no wear or tear.
3) High brake forces at high speeds.
4) Long Life
5) Low maintenance
6) Operates at any rotational speed
7) Light weight
Advantages

16. Limitations
1) Braking force diminishes as speed diminishes with
no ability to hold the load in position at standstill.
2) Need of electric power
3) It can not be used at low speed vehicles or vehicle
running at low speed

17. Applications
1) It is used as a stopping mechanism in trains.
2) For high speed passenger and goods vehicle
3) It is also used in the smooth breaking and functioning of
roller coasters and such fast moving machines.

18. 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.

19. References
 Manual 1 Gonzalez, Volume 25,Issue 4,July 2004
 IEEE Transactions on magnetics, Volume 34, Issue 4, July
1998
 Analysis of eddy current brake for high-speed railway by
Wang.P.J. & Chiuch.S.J.
 Automobile electrical equipments by Young & Griffith.
 Automatic engineering by Kripal Sing.
 Eddy Current Brakes for Haptic Interfaces, Design,
Identification,and Control
 Clutches and brakes by William.C.Orthwin.