Differential relay: purpose and scope

Difrele and difautomats are very similar devices. They differ in design and principle of operation. Let us consider in more detail their features and differences.

Basic Features

A difrel is a device that protects consumers from electric shock in direct contact with a conductive surface. For example, an uninsulated wire, an electrical apparatus, the body of which is energized.

differential relay - Devices necessary to protect against fires on equipment with damaged insulation and faulty electrical wiring. These RCDs open the circuit when they occur in the wiring if a current imbalance occurs.

The industry produces two types of difrele:

  • AC type. Such relays are designed to respond to the leakage of sinusoidal alternating currents.
  • Type A. Designed for installation in those circuits that feed equipment that has rectifiers or thyristors in its composition. That is, where, in the event of an insulation breakdown, leakage of both direct and alternating current occurs. Instructions for installing such relays are found in the operating instructions for some household appliances.

How is a difrele different from a difavtomat?

A difrele or RCD with a differential automaton has some similarities, especially external ones, but the principle of operation of these devices is significantly different. The differential relay involves an instantaneous vector analysis of the current in phase - 0.

If the sum of the vectors is non-zero, the mechanism receives a signal to open the circuit, that is, it reacts to an electric current leakage. The difavtomat responds to the so-called overcurrents that occur during overload and short circuit, although some of these devices also respond to current leakage into the ground, performing the functions of an automaton and a relay at the same time.

Since the difrele and difautomat are incredibly similar, it is quite difficult for an amateur electrician to distinguish them - you need to know the markings. Yes, and the installation of devices that can protect against fires and, as a result, ensure the safety of life and health, it is better to trust qualified craftsmen.

These units are mounted after the introductory meter in the electrical panel on a fixed DIN rail. At a voltage of 220 V, they have two terminals at the input and two at the output. In industrial enterprises and in places where a voltage of 380 V is provided, four terminals are installed at the input and output. These nuances must be taken into account for proper operation of the devices.

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