Surge protector, is also known as lightning arrester, it is a kind of electronic device to provide safety protection for the electronic equipments, instruments, communication lines. When an electrical circuit or communication line appearing a sudden surge of current or voltage caused by external interference, the surge protector can turn on the shunt in a very short time, thus prevent other equipments in the circuit from the damage due to the surge.
Surge protector, suitable for the power supply system of AC 50/60Hz and rated voltage is 220V to 380V or DC signal system, to avoid effects caused by indirect lightning, direct lightning and other transient overvoltage surges.
Surge protector is an indispensable device for lightning protection of electronic equipment, its function is to limit the instantaneous overvoltage entering the power line or signal transmission line in the voltage range that the equipment or system can bear, or transfer the powerful lightning current to the ground, to protect the equipments or system from impact.
In the control system, surge protectors can be divided into power line surge protectors and signal line surge protectors.
Power line surge protector: in order to protect the safety of control system’s power supply and electrical equipment.
Signal line surge protector: install in a signal transmission line, it is usually placed at the front of the device to protect subsequent devices, prevent lightning waves from entering the signal line and damaging the equipment. In PLC/DCS system, it is main that switch signal, 4-20mA analog and RS485 bus need protection, protect DCS card, safety barrier, relay and other equipment from lightning damage.