This is an electric braking system which works on the principle that eddy current produced in it opposes the driving torque. This opposing torque is used to brake the automobiles. Mainly this system is purely based on Faraday’s laws of electromagnetic induction and Lenz’s law.
For operating this a control switch is provided on the steering column in a position for easy manual. The skidding and complexity of mechanical braking system can be minimized by this system. Also the wear and tear of the vehicles can be reduced.
Many of the ordinary brakes, which are being used now days stop the vehicle by means of mechanical blocking. This causes skidding and wear and tear of the vehicle. And if the speed of the vehicle is very high, the brake cannot provide that much high braking force and it will cause problems. These drawbacks of ordinary brakes can be overcome by a simple and effective mechanism of braking system ‘The eddy current brake’. It is an abrasion-free method for braking of vehicles including trains. It makes use of the opposing tendency of eddy current.
Eddy current is the swirling current produced in a conductor, which is subjected to a change in magnetic field. Because of the tendency of eddy currents to oppose, eddy currents cause energy to be lost. More accurately, eddy currents transform more useful forms of energy such as kinetic energy into heat, which is much less useful. In many applications, the loss of useful energy is not particularly desirable. But there are some practical applications. Such an application is the eddy current brake.
PRINCIPLE OF OPERATIONS
Eddy current brake works according to Faraday’s law of electromagnetic induction. According to this law, whenever a conductor cuts magnetic lines of forces, an emf is induced in the conductor, the magnitude of which is proportional to the strength of magnetic field and the speed of the conductor. If the conductor is a disc, there will be circulatory currents i.e. eddy currents in the disc. According to Lenz’s law, the direction of the current is in such a way as to oppose the cause, i.e. movement of the disc.
Essentially the eddy current brake consists of two parts, a stationary magnetic field system and a solid rotating part, which include a metal disc. 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.
Since researches are going on to eliminate some of the disadvantages of this system, we can accept it to be the norm one in a few years of time.