How does a surge protection device work?

How does a surge protection device work?

There is a kind of surge protector that when the surge voltage occurs, it will cut off the power supply in time. This kind of surge protector is very intelligent, complex, and of course relatively expensive, and is generally rarely used. This type of surge protector generally consists of a voltage sensor, a controller and a latch. The voltage sensor is mainly to monitor whether the grid voltage has surge fluctuations, the controller reads the surge voltage signal of the voltage sensor, and when it is judged to be a surge signal, the latch is controlled in time, and the latch is used as an actuator to control the on-off circuit.

There is another type of surge protector circuit that does not cut off the circuit when a surge occurs, but it will embed the surge voltage and absorb the surge energy. This is usually built into the circuit board, such as switching power supply circuits will have such surge protection circuits. The circuit is generally shown in the following figure: