Phenomena of Parallel Discharges and Flashovers in Lightning Triggered to Conventional and Non-conventional Lightning Rods

摘要

Experiments of rocket-triggered lightning to a conventional lightning rod and a non-conventional Semiconductor Lightning Eliminator (SLE) were conducted in summers of 1998 and 1999 in southern China. Totally 16 lightning flashes were triggered and measured successfully. The measurements included photographs, currents and electrical fields. From the 5 lightning flashes triggered in altitude in 1998, it was found that these flashes tended to strike at the 4 m high conventional lightning rod rather than the 6 m high SLE located just 5 m away from the former. From the 11 lightning flashes triggered dedicatedly to the SLE in 1999, it was fund that there were usually a phenomenon of parallel discharges between two or more SLE rods occurring during the developing stage of lightning. In addition, there were always flashovers occurred along the SLE rods struck by lightning. Current measurements on the grounding path of the SLE have been succeeded for only one case out of five struck the SLE, probably due to side-paths caused by flashovers. The peak current measured for that case was about 6.6 kilo-amperes. The results show that the SLE is neither superior to a traditional lightning rod in terms of provision of lightning attachment points and paths for the lightning current to flow into ground, nor capable to eliminate any possibility of lightning. The lightning current-limiting function of the SLE declared by the manufacturer was not confirmed by these experiments.