Distribution of long duration current impulses in a test house lightning protection system and electrical equipment

Continuing currents, besides the main short duration return strokes, are ones of the basic components of lightning. Open air experiments were conducted to examine the distribution of continuing current components in lightning protection system, supplying cable and electrical installation of the test house equipped with household appliances. The lightning continuing current was physically simulated using a special current generator of long duration impulses. Current impulses were injected from the generator into air termination of the lightning protection system. Measured current distribution in different parts of the test house were compared with results of previous investigations for short duration lightning current impulses. A small increase of efficiency of the lightning protection system was indicated. It means that the ratio between current flowing along the cable to the grounding system of transformer station (remote ground) and current injected into the local ground was 6-8% less compared with the ratio in case of short duration current impulses representing the lightning return stroke.