Patent ID: 8582265

Claim:
A protection circuit, comprising: a first terminal; a second terminal; a current limiting device coupled to the first terminal; a solid state relay having switch terminals coupled in series with the current limiting device between the first terminal and the second terminal, the solid state relay having a control terminal and being configured to selectively decouple the first and second switch terminals from each other responsive to a control signal applied to the control terminal; a detection circuit coupled to the solid state relay and the first terminal and being configured to detect a voltage applied to the first terminal having a magnitude that is greater than a specific value, the detection circuit being configured to apply the control signal to the solid state relay responsive to detecting the voltage having a magnitude greater than the specific value; and an electromechanical relay having a relay contact switch coupled in series with the solid state relay between the first and second terminals, the electromechanical relay having a relay coil coupled to the detection circuit, the electromechanical relay being configured to automatically open the relay contact switch in response to the detection circuit detecting the voltage having a magnitude greater than the specific value.