PEN fault detection

PEN fault detection is the detection part of an EV charging safety function that looks for signs of a PEN (protective earth and neutral) conductor fault on a relevant supply. A PEN conductor combines neutral and protective functions in TN-C or TN-C-S arrangements. If it goes open circuit, conductive parts connected to the installation earth, including an EV body during charging, can rise to a dangerous voltage. Charger documents may describe PEN fault detection, built-in PEN fault protection or an open PEN detection device. The term describes the fault-detection function or status, not proof that the charger, earthing arrangement, RCD protection, circuit design, DNO process or manufacturer setup is acceptable.