Differential automaton: value, selection rules, connection

Powerful protective force from the damaging effectelectric current on the human body is a differential machine. It combines the functions of an automatic breaker and a protective shutdown device (RCD). The action of this machine is aimed at protecting the wiring from overloading, short circuits, as well as protecting a person from electricity when it enters the high voltage area and is touched by current-carrying equipment.

How to choose the necessary differential machine

Currently, preference is given todevices with high disconnecting capacity (3000 A for terminal specified devices, 6000 A for grouped) and with protection against damage to the neutral conductor. If there are several electricity consumption lines in the room, then it is better to connect a differential automat to each of them separately. You should first find out the internal voltage of the network, calculate the total power of household and lighting devices that will be connected to this line, and then buy the specified device.

The main points of the selection machine

1. Basic (nominal) device voltagemust correspond to the indicator for which this network is designed. This is an important condition. For a single-phase network, this is at least 230 V, and in the case of a three-phase network, it is within 400 B.
2. Maximum permissible (nominal) indicatorthe current of the differential automaton must not be greater than that of the corresponding electrical circuit. This will avoid network overload, overheating of conductive and insulating parts.

Procedure for self-disabling the specified device

• Inspect the circuit breaker and determine the cause of the shutdown (mains overload, short circuit, current leakage).
• Press the reset button into the case after removing the cause of the protective disconnect.

The principle of the device

Рассмотрим подробнее то, как работает differential automatic circuit, the connection scheme of which is the same as in the RCD. The principle of operation of the device consists in comparing the electric currents passing through the phases “L” and “N” (zero).

В данном случае это важный фактор.If the system is working normally, that is, electrical appliances and wiring are not broken, then the indicators will be identical. If there are problems with current output, these values ​​will differ significantly from each other. The automatic differential device will independently detect the discrepancy that arises and, if the rated leakage rate is exceeded, the power supply will turn off automatically. This is an important feature of this device. If a protective shutdown occurred, you should deal with the cause, and then turn on the device.

Tip

Differential automaton must have a solidthe body (without dents, cracks and other defects), mandatory marking on it, corresponding to the required parameters, and the mechanism responsible for switching the device on and off must be in working condition.