A differential protective machine serves as a powerful protective force against the damaging effects of electric current on the human body. He combined the functions of an automatic chopper 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 it enters the high voltage region and touches live parts of the equipment.
How to choose the necessary differential machine
Currently, preference is given to these devices with a high disconnect ability (3000 A for the terminal devices specified, 6000 A for group devices) and with protection against damage to the neutral conductor. If the room has several electricity consumption lines, it is better to separately connect a differential machine to each of them. First, you should 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.
Highlights of choosing a machine
- The base (rated) voltage of the device must 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 V.
- The indicator of the maximum permissible (nominal) current of the differential automaton should not be greater than that of the corresponding electric circuit. This will avoid overloading the network, overheating of conductive and insulating parts.
Procedure for self-disconnecting the specified device
- Inspect the machine and determine the cause of the shutdown (network overload, short circuit, current leakage).
- Press the return button into the housing after eliminating the cause of the protective shutdown.
The principle of operation of the device
Let us consider in more detail how the differential automaton works , the connection diagram of which is the same as in the RCD. The principle of operation of the device is to compare the electric currents passing through the phases "L" and "N" (zero).
In this case, this is an important factor. If the system is operating normally, that is, electrical appliances and wiring are not broken, then the indicators will be identical. If there are problems with the current output, these values will differ significantly from each other. The differential machine 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 a
protective shutdown has occurred
, you should figure out the reason, and then turn on the device.
Tip
The differential machine must have a solid body (without dents, cracks or other defects), mandatory marking on it, corresponding to the necessary parameters, and the mechanism responsible for turning the device on and off should be in working condition.