The measures required to protect devices and systems are divided into two or three levels depending on the protective devices chosen and the environmental influences to be expected. The protective devices for the individual levels differ with regard to the discharge capacity level and the voltage protection level depending on which protection level they belong to.
Three-level protection concept with separately installed protection levels:
- Type 1: Lightning current arrester
Voltage protection level <4 kV, typical installation location: main distribution
- Type 2: Surge protective device
Voltage protection level <2.5 kV, typical installation location: subdistribution
- Type 3: Device protection
Voltage protection level <1.5 kV, typical installation location: upstream of the end device
Protection levels 1 and 2 can also be implemented in a type 1+2 combined lightning current and surge arrester. This protective device meets the same requirements as type 1 and type 2 arresters. The main advantage is the easy installation. In addition, no special installation conditions have to be taken into consideration.