PTC fuses are based on a unique positive coefficient material with exponentially increasing internal resistance due to overcurrent conditions and higher temperatures. During tripping, the high resistance provided by the fuse prevents current from flowing through the circuit until the overtemperature source is removed and falls below the design current/temperature limit. Once the fault current is removed or the ambient temperature cools, the fuse re-enters the conductive state, allowing current to flow through the circuit again.
