Detection of tracking of cord plug based on surface current characteristics

Tracking of a plug for household appliance connected to an outlet is considered as one of causes of fire, which is occasionally observed when dust is accumulated in the space between the plug and the outlet and wetted by dew condensation. By carrying out a series of fundamental studies, surface current were recorded and analyzed, which flowed on the surface of a cord plug during accelerated tracking tests using electrolytic solution and cotton. In the practical conditions, it seems difficult to detect surface current only, since its magnitude is much smaller than that of a typical load current. Based on characteristics of surface current, a new physical quantity was introduced and the feasibility of detection of tracking using this quantity was discussed.