What is a surge protective devices (spd)?

What is a surge?

A surge is a transient interference that causes an instantaneous voltage on the grid to exceed the range of the rated normal voltage under certain conditions. Usually this transient does not last too long, but may be quite large. It is possible that the instantaneous surge in just one millionth of a second, such as thunder.Or disconnection of the inductive load, or the moment a large load is connected, will have a great impact on the grid. In most cases, if the device or circuit connected to the grid does not have surge protection measures, it is easy for the device to be damaged, and the degree of damage will be related to the withstand voltage level of the device.