Fault current protection device - responds to fault on short-circuit supply lines to operate line protection fuse

摘要

The protection device provides a short-circuit across the current lines, causing a line protection fuse (2) to be operated its impedance being adjusted via a series current limiting resistor (9), so that with a low network impedance the short-circuit switch is protected against false operation. However, with a high network impedance, the short-circuit current is rapidly attained. The series resistor (9) is able to handle the max. short-circuit current without being damaged. Pref. the device uses a thyristor or a triac (8) between the current lines triggered to provide a short-circuit if water penetrates the device. The device can be used on its own or to provide a back-up protection if a fault current switch fails.