The principle of operation of the RCD



  1. What is an RCD?
  2. RCDs come in two types
  3. The principle of operation of the RCD
  4. Varieties of RCD

What is an RCD?

The abbreviation UZO stands for: DEVICE PROTECTIVE SHUTDOWN. In other words, the device is intended to protect humans or animals from electric shock, Other types of RCDs are designed to protect against fires.

The history of RCDs is rooted in the years 50-60 last century. Initially, the device looked primitive, but today it is a fairly reliable device, although there are fakes.

The purpose of the RCD is to protect property from fire, and also protect a person from electric shock. We are all good We understand that electric current is the basis of modern civilization, and we are in close contact with powerful energy invisible to our eyes. But such a force may at some point prove fatal. For sensible engineers came up with fewer such cases RCD.

Do not confuse RCDs with devices such as automatic circuit breaker VA or with differential circuit breaker.

Read the following articles about RCDs:

  • How to distinguish a differential machine from an RCD?
  • What types of RCDs exist and what is their difference?
  • How to connect an RCD? DIAGRAM

RCDs come in two types

1. Protection against damage electric shock. The minimum level to disable instrument 10 mA and 30 mA. The most common 30 mA. 10 mA Designed for wet rooms and most often installed for protect the bathroom. It would be possible to install an RCD on each a separate group of consumers, but it is very expensive. More economical install one RCD on three to four separate groups of electrical chains.

If an RCD trips, you can do a simple procedure troubleshooting. Turn on automatic switches “sitting” under the RCD, and so, you find out in which A group of consumers has a current leak. Some consumers require a separate RCD, for example, such as: an electric boiler, refrigerator or computer. This is done in order to ensure stability to devices, if there is an urgent need for it.

The principle of operation of the RCDThe principle of operation of the RCD

2. “Fire” RCD. At such a device has a coarser cutoff: 100 mA, 300 mA, 500 mA. FROM with such a rating to turn off the current the device does not protect a person from electric shock (considered 50 mA hazardous to health). Why is this kind of fire called? Due to insulation damage wiring or network congestion, short may occur short circuit and fire. As soon as an electrical circuit occurs sensitive leakage, RCD will cut off the power supply of everything buildings, not allowing a short circuit, i.e. will not happen sparking and ignition. The device “stands guard” throughout electrical wiring of the building. Fire RCD is installed immediately after the electric meter.

The principle of operation of the RCDThe principle of operation of the RCD

The principle of operation of the RCD

Inside the appliance there are three magnetic coils. Through the first phase passes through the second zero. Current creates magnetic glade inlet and outlet coils of the device. Under normal mutual fields destroy each other. If on one of unbalance occurs in the case of coils conductor, there is a leakage of current to the ground. Such “problem” will give the command to the action of the third coil, which has relay disconnecting power.

wiring diagramwiring diagramwiring diagram

Varieties of RCD

There are two versions for this device. Bipolar (2P) – for a single-phase network and four-pole (4P) – in three-phase network.

UZOUZORCD: appearance

Before installing an RCD, read a few useful articles: Electricity is by no means harmless; read the rules electrical safety.

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