A relay is a machine that has a low amount of electricity that moves through the coil, wires, and small bars to power other machinery. Relays were one of the first types of machines to generate power for other machines. Though they were the first of there kind, they work very well. Relays don 't use much electricity, but can power something that does. That is why relays are still used today.
Relays have five different parts. The first part is the electromagnetic coil. The coil is powered by what ever you use as the source of electricity which when activated will make the coil pull down the armature to complete the circuit. The next part is armature which is a metal arm that is also a non-completed circuit that once power is turned on the electromagnet will pull down the armature and the circuit will be complete. The third part is the spring. The spring pulls the armature back after the power is shut off. The fourth part is the source of power which supplies the power needed for the relay to work. And finally the fifth part is a switch or button which turns on the power. Those are the essential parts to a relay.
The relay has very little power as I told you earlier, but the armature raises the amount of power. For example the coil can energize two hundred fifty milliwatts. When the armature is connected that can go up to two hundred and forty watts. That is a big raise in power. That is how strong a relay is.
Sometimes you need to cascade a relay. That just means you need to take a small relay to power a bigger relay. When you do this the small relay acts as the source of power for the big relay. Cascaded relays are used in fuse boxes and cars usually.
A relay has five variables that you can control. The first is "the voltage and current that is needed to activate
Bibliography: .www.electricclub.com2.www.encyclapedia.com3.www.howstuffworks.com4.www.schoolnet.com