低圧配電線に生じる誘導雷過電圧の実験的検討

Abstract

Problems have often been caused in low-voltage distribution lines such as single-phase 100/200 V and three-phase 200-V systems. For instance, the burning of low-voltage devices and the unnecessary operation of ground fault interrupters have occurred, which are caused possibly by lightning overvoltages. Experimental analysis was performed on the generation modes of lightning overvoltages on low-voltage distribution lines. A scale model line, one-fourth the size of an actual power distribution line of Tokyo Electric Power Company (TEPCO), was installed for experimental analysis on the lightning protection of an overhead ground wire, an overhead common grounding wire (system neutral conductor), surge arresters and pole transformers against the overvoltages induced on low-voltage distribution lines due to a nearby lightning stroke. A balloon was flown at a location 30 km away from the scale model line in a normal direction to it. A 200-m long wire is suspended from the balloon to simulate a lightning path. Pulse current is applied to the simulated path using a pulse generator and the voltages induced on the line conductors are measured. This paper analyzes those overvoltages by means of the experimental and the theoretical methods.