Transient false tripping characteristic analysis of ground fault circuit interrupter

GFCI (ground fault circuit interrupter) is widely used to prevent from fire hazards, electronic shock and injury to persons by a persistent earth leakage current. On account of a application of GFCI, however the occurrence of false tripping due to lightning and switching surge has been growing. This unwanted tripping caused by the transient ground potential rise due to nearby lightning strokes could bring about a fatal loss like a power outage or a deterioration of power quality. In order to analyze the cause of malfunction, various samples of GFCI were investigated experimentally. When lightning impulse and EFT (electrical fast transient) were injected to GFCIs with the different leakage current detecting circuits and the wiring configurations, various false tripping characteristics were showed. Most of them showed malfunctions under surge current less than 3 kA. Also, it was found that a false tripping is dependent on a wiring of GFCI circuit and position of protective component Countermeasures using MOV (metal oxide varistor) and zener diode were suggested to prevent from a false tripping in this study.