Electromagnetic relays

The relay consists of an electromagnet and one or more contact groups controlled by a drive mechanism connected to the armature of the electromagnet.

Relay contacts can be make, break and changeover.

On electrical diagrams, the relay contacts are represented by the same symbols as in the conventional images of switches and switches, and the electromagnet is in the form of a rectangle with leads.

Electromagnetic relays are very common elements of automation and are used in many areas: automatic control, telemechanics, automation of production processes, household appliances, etc.

Automatic systems can contain hundreds, sometimes thousands, of different types of relays.

There are relays in which the magnetic field created by the control current of the winding acts directly on the sensitive (magnetically controlled) contacts enclosed in a sealed case (they are also called reed switches - an abbreviated word from the words Hermetic CONTACT).

To distinguish such a contact from other types of contacts, the symbol of a sealed case is introduced into its designation - a circle.

Belonging to a particular relay is indicated in the reference designation (Fig. 2, a).

If the magnetically controlled contact is not part of the relay, but is controlled by a permanent magnet, it is designated by the letter code of the circuit breaker - the letters SP (Fig. 2, b).

The widespread use of electrical relays is due to their two main properties: the ability to control electrical circuits at a distance and the ability to control sufficiently powerful processes using very small electrical signals.

The power amplification factor of electrical relays can reach tens of thousands.

Drill disassembly

In the course of their work, electricians sometimes have to deal with various documentation. This can be for example:

wiring diagram

drawing

or house plan

So you need to know not only wiring diagrams.