We know overvoltage and undervoltage protection devices are important over-under voltage protection device, usually installed in the power distribution box entrance, its main role is to appear in the circuit overvoltage or undervoltage condition of a circuit or load protection. Its working principle looks very simple, but when the circuit overvoltage or undervoltage protector, can cut off the power supply for the circuit and electric load protection; when the circuit voltage is recovered, with self recovering function (i.e. automatic recovery function) of the over-voltage protection device can automatically connect the power supply.

Overvoltage and undervoltage protection devices sounds very simple but complex, the whole process is very complex, the whole process needs the interaction processing module, data module, power module, self recovery module, delay module, indication module and alarm module, the following will introduce the working process of the product.

When the data sampling module real-time voltage monitoring circuit, when the detected circuit overvoltage or undervoltage, processing module directly to the signal delay module, time delay module of the received signal, the countdown time delay. When the delay time is over, the circuit is still in the state of over voltage or under voltage, and signals are sent to the power failure module and the indicating module simultaneously. The power supply module interrupts the power supply directly after receiving the signal, and at the same time, the indicating lamp of the indicating module immediately displays the corresponding overvoltage or undervoltage indicating lamp, and if the protector with alarm function is issued, the alarm is sent out.

When the data sampling module detects the power supply circuit is restored to its normal voltage, data sampling module to the signal processing module, signal processing module receives the control module, delay time, delay time after the voltage of the circuit is still normal voltage, since the complex module immediately switched on, normal power indicator light module play.

The above is the working process of the overvoltage and undervoltage protection devices from normal voltage to under voltage or overvoltage, and return to normal voltage, the whole process or by the interaction of each module, information exchange between modules, to protect circuit and electric load.