Abstract
On a 66kV overhead transmission line equipped with arcing horns, a two-phase short-circuit fault between an upper and a lower line caused by a lightning strike turned into a three-phase short-circuit fault. And, a round inspection after the fault revealed that there were many partially-melted spots on a jumper wire of middle line. In order to clarify the mechanism of the fault experimentally, the short-circuit tests were carried out by using the full scale apparatus considering the installation conditions of the arcing horns on the actual lines. The arc was ignited between arcing horns installed on the lower line, and the aspects of the phase-to-phase short-circuit fault between the lower and the middle line were observed by using the high speed videos. As a result, the arc jets spouted upwards from the arcing horns of the lower line, and the arc showed a tendency of rising easily due to the arc jets. These results suggested that the hot gas generated by the arc and the arc jets caused the breakdown between the lower and the middle line, and the phase-to-phase short-circuit fault occurred. Considering the breakdown phenomena, a countermeasure against the short-circuit fault was investigated.
