01-05-2013, 03:56 PM
INTRODUCTION OF EDDY CURRENT
EDDY CURRENT.pptx (Size: 147.92 KB / Downloads: 16)
INTRODUCTION
Eddy currents are electric current induced in conductors when exposed to a changing magnetic field, due to relative motion of the field source and conductor or due to variations of the field with time.
This can cause a circulating flow of electrons or current with in the body of the conductor.
These circulating eddies of current have inductance and thus induce magnetic fields.
ROTATIONAL EDDY CURRENT BRAKE SYSTEM
Electro magnetic brakes are similar to electrical motors
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 electric magnets. The movement of the metal through the magnetic field of the electromagnets creates eddy currents in the discs.
These eddy currents generates an opposing magnetic field lenz’s law, which then resists the rotation of the discs, providing braking force.
The net results is to convert the motion of the rotors into heat in the rotors.
WORKING PRINCIPLE
Magnetic field lines across the magnetic material inside a copper tube.
Direction of magnetic lines of force due to magnet in copper tube.
Induction of eddy current due to the motion of magnet in the copper tube. 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 speed
Used also as service brake
It uses electromagnetic force and not friction non-mechanical can be activated via electrical signal light weight.
APPLICATIONS
It is used as a stopping mechanism in trains
It is also used in the smooth breaking and functioning of roller coasters and such fast moving machines
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