Electromagnetic relays are those relay which operates on the principle of electromagnetic attraction. It is a type of a magnetic switch which uses the magnet for creating a magnetic field. The magnetic field then uses for opening and closing the switch and for performing the mechanical operation.. Modern electrical protection relays are mainly micro processor based, but still electromagnetic relay holds its place. It will take much longer time to replace all electromagnetic relays by micro processor based relays.Electromagnetic Relays are widely used in machine tool control, industrial assembly lines, substations and commercial equipment.The working mechanism of electromagnetic relays is simple to understand. An electromagnetic relay is composed of electromagnet, armature, spring, movable contact and a stationary contact.The electromagnetic relay operates largely as per the principle of electromagnetic induction, which also means that as the electric current is passed on the conductor, the conductor behaves like a magnet.So, as you switch on the power in the circuit, the current goes through the coil of the electromagnet and the coil gets activated by a supply system. Thus, generates a magnetic field. On this, the armature generates a suction force to connect the movable contact and stationary contact. The relay switch consists of a solenoid that has a fixed iron core and a part which is movable. A spring is often used to provide the force to hold the movable portion (the armature) away from the fixed portion (the stator or core) when the solenoid is de-energized. When the coil is energized, the armature is pulled against the stator, closing the magnetic circuit and mechanically closing (or opening) one or more sets of contacts. Relay switches operate electrical contacts for closing or opening a circuit, while solenoids operate a plunger to effect a mechanical operation.
–AC 220V, 50-60Hz, Cos Ǿ=0.4 : 5A
–DC 220V, L/R= 45ms : 0.5A
