Matt circuit

Electromagnetic Relay acts as a electrical switch operated by electromagnet. The coil on the relay forms the electromagnet. When excited by rated voltage, it pulls the moving portion of the relay contacts towards it resulting in electrical contact. Thus it turns a load circuit ON or OFF by energizing an electromagnet, which opens or closes contact in the circuit. A relay has one coil, but may have many contacts. The contact that changes is called pole and the non-moving contacts are called ways. When the coil is off, the contact with pole is called normally closed contact. (NO) The contact established after the coil is energized is called normally open contact. (NC) The coil and the contacts of a relay are electrically galvanically isolated from each other.   Relays finds wide use in timers, interlocks circuits, trips and safety units, changeover systems etc. The main parameters required for selection of a relay are, 1. Coil rating  2. Contact rating.  3 Operation ...

 A special type of relay is one which monitors the current, voltage, frequency, or any other type of electric power measurement either from a generating source or to a load for the purpose of triggering a circuit breaker to open in the event of an abnormal condition. These relays are referred to in the electrical power industry as protective relays . The circuit breakers which are used to switch large quantities of electric power on and off are actually electromechanical relays, themselves. Unlike the circuit breakers found in residential and commercial use which determine when to trip (open) by means of a bimetallic strip inside that bends when it gets too hot from overcurrent, large industrial circuit breakers must be “told” by an external device when to open. Such breakers have two electromagnetic coils inside: one to close the breaker contacts and one to open them. The “trip” coil can be energized by one or more protective relays, as well as by hand switches, connected to swit...