Look at the housing panel or distribution Board, located on the landing. In addition and metering of electricity consumption, it is possible to see the fuses or circuit breakers that protect the network from overload currents and short circuit generated by the energy consumer.
Much less frequently the guards are equipped with protective devices (RCD), stops the supply of power in case of the leakage current through the damaged insulation of the cable, thus preventing the defeat of man by electric current and prevent fire.
And very rarely the company of the aforementioned devices constitute a voltage relay whose main purpose is to monitor the quality of the incoming mains electricity, and in the case of output values of voltage outside of permissible limits — to stop the supply of power to the apartment. Why the cut off voltage so little in our shield? The reason is simple: it is considered that the electricity supplied to end-users, has a stable voltage of 220 V and additional processing does not need.
a power Surge. Its causes and consequences
Actually, the situation with the quality of the supplied electric power is not easy. Quite often as a result of lightning discharges, various overloads, failures in the supply network or distortion of phases caused by the erosion or breakage of a zero wire, the voltage fluctuates in a fairly wide range – from 130 to 380 V.
Excessively high value of the electric current leads to overheating of the electrical elements and the violation of the integrity of their insulation. As a result, the device-the power simply fails.
In the case of low voltage developed by the electric motor power is insufficient to start the rotational motion. It is not surprising that the rotor of the motor of the refrigerator or the vacuum cleaner remains stationary or rotates at reduced speed, which inevitably leads to failure.
With the task of protection consumers of electricity from surges, overvoltage or undervoltage is most effectively cope voltage relay, consisting of electronic devices voltage control and power part of the load disconnector.
If voltages outside the pre-programmed range (for example, 190 – 250 V), the microprocessor sends a power part of the command to stop the supply of power to the load. The network de-energized, relays continuously monitor the voltage and if it went back to normal, after the programmed period of time (the recommended value is 6 minutes) the flow of electric current is resumed.
Depending on the connection method the device can be made in the form of a module with a plug, and in the form of power strips, sockets or extension cords. To power these relays simply set the plug into the wall outlet.
Radically different from the devices installed in the cabinets, panel and supply electricity to the whole apartment.
For the vast majority of apartments required single phase voltage cut-offs. If housing or industrial premises supplied with three-phase current, to protect its equipment against power surges you can install one single-phase relay for each phase.
Why to use 3-phase voltage relay? The answer is simple: when using 3-phase relay, in the case of minor imbalance or power failure on one phase, the relay will disconnect all 3 phases, including the two who have nutritional problems were observed. The main purpose of the 3-phase relay protection these 3-phase electric motors in air conditioners, compressors, refrigeration and various industrial machines.
Choosing voltage relay, pay attention to the nominal value of current. The fact that the number, expressed in amps, is the amperage that the relay can pass through without harm to its health. This does not mean that if this current shutdown voltage will be able to open its contacts, interrupting power to the consumers.
Therefore, you should focus on the value incoming circuit-breaker installed in the distribution panel. The current value of the relay should be 20-30% above the face value of the switch. Simply put: if the machine is designed for 25A, the value of the cutoff voltage should be no less than 32 A.
Equally important is the rate of load rejection. Stop your choice on models with the value in 0,02-0,10, refusing to buy cheaper devices with the speed off to about 1 s. Protect electrical devices in your home using the relay voltage may be the voltage supplied to them will always be within the values specified when setting up the product.
Good luck to you! Let you will succeed!