Experimental study on short circuit phenomena in air switch of distribution line due to lightning overvoltage on which one surge arrester of the three ones is omitted

We experimentally examined the possibility of the internal short circuit of an air switch due to the sparkover between different poles under the condition that no surge arrester exists in neighboring poles and one of three surge arresters is omitted at the pole with an air switch. Experiments at Shiobara Testing Yard and Akagi Testing Center of CRIEPI clarified the following. Fault current may flow via the grounding point of a pole with an air switch and that of the next pole on a different phase from grounded phase of the pole with an air switch. If the low-voltage wire, overhead ground wire or communication wire forms a short circuit between them, ultimately the air switch may burn out. Moreover Fault current continues even if the length of the short circuit between different poles is increased. Although the increase of the short-circuit length results in the increase of wire impedance, the amount of increase is still small compared with source impedance.