A surge protector protects electrical and electronic devices from excessive electrical voltages. Surges can have various causes.
- Lightning strikes (lightning electromagnetic pulse)
- Sudden drop in load / increase in load
- Switching operations (switching electromagnetic pulse)
- Electrostatic discharges (electrostatic discharge)
There is a three-stage concept for protection against overvoltages.
Stage 1
A coarse protection (SPD type 1, Surge Protection Device) protects against high-energy disturbances. For example, it prevents lightning from entering the line to be protected. It is designed to limit the residual voltage to 1300 to 6000 V.
Stage 2
A medium protection (SPD type 2) is usually located in floor distributors. It is designed to limit the overvoltages to 600 to 2000 V.
Stage 3
Fine protection (SPD type 3) is the protection of sockets and connectors.