Voltage relay: principle of operation and scope

Modern electronic devices can not do without protection from unacceptably low or high voltage of the mains. To implement these functions, a variety of threshold schemes have been developed. The principle of their operation is based on a device called a voltage relay. In addition to protective functions, such schemes are used in the automation of production processes, they can be found in household appliances, they are successfully used in the automotive industry, etc. The use of a voltage relay has long been a sign of good design in the development of circuits for electrical and electronics.

Let's look at some examples of using such devices. Overexertion or its loss is a serious problem, with power failure, all electronics will fail with different consequences. With the inclusion of powerful engines in production, there may be a shortage of power to the supply network, which will adversely affect the operation of all devices. The failure of the electronic circuits participating in the management will lead to the creation of emergency situations and the shutdown of the entire technological line. Overexertion will also lead to negative consequences. To minimize losses, a voltage relay is used in this case . They are compact, reliable in operation and differ only in basic elements.

They work on the following principle. If the actual voltage exceeds the setpoint, a voltage relay is activated, which protects the circuit. By the same principle, protection circuits operate in the event of an unacceptable drawdown of the supply network.

Separately, you can consider the use of such devices in the automotive industry. They monitor the condition of the on-board network and prevent the voltage from rising above a specified level. Usually this is realized by limiting the stator winding current of the generator, which feeds the battery with the engine running.

Currently, serial production of such devices has been established. For example, the single-phase voltage relay RN-111 is designed to shut off consumers inadmissible fluctuations in the supply network. After restoring all the parameters, it will automatically turn on.

The relay has an indication of the presence of power, which simplifies troubleshooting. In addition, on the front side there are potentiometers for setting the minimum and maximum trip voltages. This also provides visual control over the relay parameters and simplifies the initial setup. Also, there is a delay for triggering during short-term fluctuations in the network. In addition to overvoltage protection, it performs the functions of a minimum voltage relay. A large number of changeover contacts makes it possible to use them both for protective shutdown and for monitoring and automation circuits.

In addition to relay protection, there are various electronic circuits that perform the same function. The advantages of such schemes include high sensitivity and speed. The disadvantages are the complexity in manufacturing and low reliability.