In line with signal potentials, a distinction is made between 3-point and 5-point protection.
In case of connection modules, only 3-point protection is possible.
Switching modules are basically recommended for 5-point protection (components in the signal path) because - once the protective plug has been removed - the contact in the module is open, so that possible faults cannot make their way to the downstream network. 5-point protection can also be implemented using disconnection modules.
KRONE supplies various types of protective circuits:
3-point protection: pure overvoltage protection (high-voltage or secondary protection)
5-point protection: overvoltage protection combined with current protection
5-point protection: graded protection (high-voltage and secondary protection with current protection).
Protective circuits with an integrated fail-safe feature are highly recommended. Components for overvoltage protection are usually designed for pulse-shaped loads only. Therefore, if permanent overloads are possible (e.g. mains contact), a safe short-circuit to earth must be ensured. Overloaded or overheated protection components would not only lose their protective function, they could cause fire or an explosion thereby leading to considerable damage.