Relay

relay

relays coil

The relay is actually an electromagnet, which when voltage applied to the ends of the coil attracts and retains an iron, or more properly a part of several steel parts, insulated from each other.
At the end of the movable iron part have adapted one or usually more electrical contacts, insulated from one another as well as to the electromagnet.
As the voltage across the coil exists, there is magnetism. When you stop the voltage, a spring that has meanwhile compressed is geting back the electrical contacts.

parts of one relay

relays label

If contacts are at rest, ie when there is no current in the coil of the relay the contacts is open, then when magnetized, closed and vice versa. The open marked as Normally Open (NO) and closed as Normally Close (NC).

There is great variety in the number of contacts, size and operating voltages of the coil.
There relay specially constructed to withstand more effectively in resistive (eg, resistance heating), inductive (eg motors) or capacitive load (eg compensation capacitors)


A form of relay common in industry and in control of three phase electric motors is that of photographs.

relays contact

Smal finder relays

The voltage of the coil is not usually printed on the relay label but in the body that carries the coil, which is an accessory that can be changed.
Problem dysfunction can occur after heavy use or poor choice of power or damage to load - consumption control. Usually the power contacts are those most frequently damaged.


The ends of the coil Names as A1 and A2 in the majority of manufacturers relay.

relays contact

Electronic board with relays

This relay photos marked as 5,5 KWatts relay at 24 volts AC, which means that for 400 volts three-phase network, is designed to withstand, the usual applications, three-phase motors up to 5,5 KWatts and coil built to 24 Volts alternating current (AC).
The contacts withstand current for motors 5,5 KWatts called power contacts and is three Normally Open, one for each phase.
The remaining contacts in the auxiliary relay are designed for low current and are from one to six. They also called contacts or auxiliary automation.
Usually an auxiliary NO is standard in main body of the relay, and if we want more NO or NC we must to buy separately and add them to the socket on the relay and are usually clipped