Differential automaton: value, selection rules, connection

A powerful protective force from the damaging action of electric current on the human body is a differential automaton. It combines the functions of an automatic interrupter and a residual current device (RCD). The action of this machine is aimed at protecting the wiring from overload, short circuits, as well as protecting a person from electricity when they get into the high voltage area and touching current-carrying elements of equipment.

How to choose the required differential automaton

At present, preference is given to these devices with a high tripping capacity (3000 A for terminal devices, 6000 A for group devices) and with protection against damage to the neutral conductor. If there are several lines of electricity consumption in the room, it is better to connect the differential automaton separately to each of them. Preliminary it is necessary to 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 moments of automaton selection

1. The basic (nominal) voltage of the device must correspond to the indicator for which the 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 V.
2. The maximum permissible (nominal) current of the differential automaton should not be greater than that of the corresponding electrical circuit. This will avoid overloading the network, overheating the conductive and insulating parts.

Procedure for self-disconnection of the specified device

• Inspect the machine and determine the cause of the trip (network overload, short circuit, current leakage).
• Press the reset button after removing the cause of the protective shutdown.

Principle of operation of the device

Let us consider in more detail how the differential automaton works, the connection scheme of which is the same as in the RCD. The principle of the device is to compare the electrical currents passing through the phases "L" and "N" (zero). In this case, this is an important factor. If the system operates normally, that is, electrical appliances and wiring are not violated, the indicators will be identical. If there are problems with the current output, these values will differ significantly from each other. Automatic differential will independently determine the inconsistency and if the nominal leakage rate is exceeded, the power supply will turn off automatically. This is an important property of this device. If there is a protective shutdown, you need to understand the cause, and then turn on the device.

Tip

The differential automaton must have a one-piece body (without dents, cracks and other defects), mandatory marking on it, corresponding to the necessary parameters, and the mechanism responsible for switching the device on and off must be in working order.