Question 9:  How electromagnetic brakes work? Explain.

Answer

Eddy current brakes

Eddy currents brakes were first proposed by French Physicist, Foucault. Such brakes are used in a wide range of fast moving objects.

Working Principle of eddy current brakes

Electromagnetic brakes work on the principle of eddy currents produced through electromagnetic induction.

There are two types of Electromagnetic brakes; (1) Linear EM brakes (2) Circular EM brakes.

Linear Electromagnetic brakes

Linear eddy currents brakes have tow component; one is stationary and the other moves past it in a straight line. Usually, the stationary part is a heavy magnet and the other part is the object which we want to stop. As the moving object approaches the magnet (stationary), eddy currents are produced in it (i-e, in the moving object). These eddy currents have their own magnetic field (phenomena of electromagnetic induction). The two magnetic fields are manipulated in such a way that their interaction makes the moving object stop.

Circular EM brakes

Like linear electromagnetic brakes, circular EM brakes also have two parts; one static and the other moving. Further, in some cases, the electromagnetic part is static and the other is moving and in some other cases, the electromagnetic part is moving and the other is static.

In its simplest form, the electromagnet part is stationary and a metallic disc is rotating inside it. When current passes through the electromagnet part, eddy currents are produced in the metallic disc which develops its own magnetic field. Again these magnetic fields interact and as a result the moving disc comes to a halt.

Advantages

Normal brakes work on the principle of friction, i-e, rubbing of two surfaces. This makes the surfaces wear out by friction. On the other hand, eddy currents brakes work on the principle of electromagnetic induction and there is no rubbing of surfaces. Therefore, the life time of the machine is increased.