How does a Relay works?

Question

Relay...How do they works? What is their purpose in electrical?

Answer 1

Relays are very simple. They are an electromagnet - a coil of wire wound on an iron core - that operates switch contacts. If you think of a robot throwing a switch you have the idea. A small current can switch large currents and the relay provides isolation so - for example - something that just provides a connection to ground can connect 12 volts to turn on a pump.



The contacts are described by their number and how they connect and disconnect. Each independent set of contacts is called a pole - I have no idea why - and the open/close characteristics are called throw. A set of contacts that only open or only close are called single throw, while a set of contacts that open on one side and close on the other when energized is called double throw. The single throw contacts are also described as normally open (no contact when the relay is not energized) and normally closed (contact when the relay is not energized) - both are meaningless with double throw contacts.



Most automotive relays have coils designed to operate at 12 volts DC, usually at a couple tens of milliamps, and have single pole or double poles. Normally open is more common than double throw, which is in turn more common than normally closed. Relays designed to have AC applied to the coil are also made - applying AC to a DC relay will just make it buzz.

Answer 2

When power flows through the first circuit (1), it activates the electromagnet (brown), generating a magnetic field (blue) that attracts a contact (red) and activates the second circuit (2). When the power is switched off, a spring pulls the contact back up to its original position, switching the second circuit off again.



This is an example of a "normally open" relay: the contacts in the second circuit are not connected by default, and switch on only when a current flows through the magnet. Other relays are "normally closed" and switch off only when the magnet is activated, pulling or pushing the contacts apart. Normally open relays are the most common.



Here's another animation showing how a relay links two circuits together. It's essentially the same thing drawn in a slightly different way. On the left side, there's an input circuit powered by a switch or a sensor of some kind. When this circuit is activated, it feeds current to an electromagnet that pulls a metal switch closed and activates the second, output circuit. The relatively small current in the input circuit thus activates the larger current in the output circuit:



a.)The input circuit is switched off and no current flows through it until something turns it on. The output circuit (blue loop) is also switched off.

b.)When a small current flows in the input circuit, it activates the electromagnet, which produces a magnetic field all around it.

c.) The energized electromagnet pulls the metal bar in the output circuit toward it, closing the switch and allowing a much bigger current to flow through the output circuit.

d.)The output circuit operates a high-current appliance such as a lamp or an electric motor.





https://www.electrikals.com/products/rmc-havells/control-relay-cosmic-star?mid=28&cid=750&rid=690&page=1&pagesize=30

Answer 3

The main operation of a relay comes in places where only a low-power signal can be used to control a circuit. It is also used in places where only one signal can be used to control a lot of circuits. The application of relays started during the invention of telephones. They played an important role in switching calls in telephone exchanges. They were also used in long distance telegraphy. They were used to switch the signal coming from one source to another destination. After the invention of computers they were also used to perform Boolean and other logical operations. The high end applications of relays require high power to be driven by electric motors and so on. Such relays are called contactors.

Answer 4

1. Inductor is simply a coil of wire that is usually used to limit EMF. In radios, inductors are used to control frequency. Huge inductors called shunt reactors are used to limit distribution grid voltage when power consumption decreases. 2. In radios, inductors are used along with capacitors in control circuits to control frequency. 3. A relay is a coil and switches. When the coil is energized by a trigger (such as you pushing a button), electrical current passes through the coil and the generated magnetic field causes the switches (contacts) to change state. Open ones close, and the closed ones open. 4. ICs are miniature dedicated circuits using semiconductors.

Answer 5

A relay takes a high current circuit and uses low current to turn the high current on and off. Its basically a high current switch. There are coils that are designed to handle the high currents constantly. A switch could do the job of turning circuits on and off but has a drastic higher failure rate.

Answer 6

it is like a fuse. it regulates power to the part receiving it.