Electromagnetic relay is an integral element of most electronic devices, so you should clearly understand the basic characteristics and the principle of operation of the relay. The main element of any electromagnetic relay is an electromagnet. The simplest electromagnet consists of a coil, usually wound from copper wire, and a core, called a yoke and made of an iron-containing metal, as the latter mainly used special electrical steel. When current flows through the coil windings, a magnetic field is created, which is additionally enhanced by an iron core. Under the action of a magnetic field, metallic iron-containing objects, such as cloves, are attracted to the electromagnet.
An electromagnetic relay works in a similar way, only instead of studs, an anchor is attracted to the core, overcoming the force of the breaking spring. The constructional anchor of the relay is connected to a moving contact, which moves along with the anchor and thereby closes the open contacts or opens the closed contacts.
The main advantages of electromagnetic relays are: galvanic isolation of power circuits with control circuits; low contact resistance. Disadvantages of the relay: low frequency on and off; wear of moving parts due to friction.