Protective device and communication device

摘要

The present invention is to inform a state where a communication device connected to a communication wire and a power line is protected from a surge current. The toroidal coil picks up a rapid increase of current caused by a rapid increase of voltage which occurs in the communication wire and/or the power line, to supply the current from the toroidal coil to the current detecting unit. The current detecting unit converts the current from the toroidal coil into a voltage and supplies it to a switching circuit. The switching circuit turns on the indicator light circuit to light up the LED of the indicator light circuit.