What is relay | define relay

 

What is relay?

Relay is the electrical and electronics device or component, it used for the electrical switching.

The relay is basically used for switching, because it can switching high current's load by low signal, it also used for link or line change, means it works as a changeover switch, but it’s one special thing it can change current line without load stop, such as voltage stabilizer, or auto change over, etc.

How to relay works

The Relay works on electromagnetic, the relay inside has a coil which make magnetic field by electrical current.

 

Any relay has a connector that is first connected to the one point or terminal, when the coil energized by electric current, it makes electromagnet and pulls the connector towards it, thus when connector pulled down then it connect to other terminal or point.

The coil of relay is totally separated from other load's terminals, which current we provide to relay's coil, that current can't connect to other load's terminal, for this we can easily use one relay in both currents such as "AC" and "DC", because many relay's coil mostly operates by DC current.

The typically used relay has DC 12v coil, means it operates by 12v current, and we most use this relay in Electronics Circuits, Cars, or Electrical appliances switching, and etc.

We can operates our equipment by remote or electronics signals with help of relay, and also we can operates heavy load's appliances by one low ampacity or small button, such as Car's headlights, because car's headlights consume very high current, but it we operated by small button, because the Relay take load of headlights, and button take load of relay's coil, and coil consume very low current, near about milleampere, for this the low ampacity's button can operates our heavy appliances.

The relay mostly used in voltage stabilizer, UPS, etc.

Because stabilizer having a transformer which have many links, the each one link has different voltage, in which we need to change according to the input voltage, so we use relays for links changing so that voltage will change but our load not be stop.

How to use relay / How to do connection of Relay

The relay's used or connection is very easy

The any relay have two terminals of coil, and other terminals one terminal is common and second pin is normal close and third pin is normal open, if relay's coil not energized so it remain at normal close point when coil energized by current then relay's connector move to normal open point, thus common pin will connected with normal open pin.

The normal close pin means its work in normal condition, and relay's normal condition means when its coil not energized by current.

So you known that coil connect with DC current, and common pin connect to our load, which load we want to run, and normal close pin connect to source, which source we require for load in normal condition, and normal open pin connect to our other source.

like this

In Fig 1 Bulb glows on Battery because relay’s coil is not energized, and in Fig 2 bulb glows on Power supply because power supply has energized coil of relay.