Rationalization of Countermeasures against Failure of Surge Arresters by an Effective Installation Method of an Overhead Ground Wire Considering a Telecommunication Wire

In Hokuriku area, surge arresters on distribution lines are often damaged due to direct lightning strikes, particularly in winter. It is reported that installing an overhead ground wire (OGW) is effective countermeasures. However, adding the conventional OGW to existing distribution lines needs high costs and power interruption for construction because of installing them above phase wires. Therefore, an overhead ground wire installed under phase wires (UGW) has been proposed as a shunt path for lightning current. Recently, in some areas, in order to reduce the cost of maintaining the OGW, the wire is removed and only the support metal is left on the pole top for construction convenience. Observation results have been reported that the lightning attraction effect of the remaining support metal increases the frequency of lightning strikes to the pole top and decreases the frequency of lightning strikes to the mid-span. In this paper, in order to estimate the effect of the UGW more accurately, these effects and a telecommunication wire installed on actual distribution lines are taken into account. In addition, in order to rationalize countermeasures against failure of surge arresters, the failure probability of surge arresters and the countermeasure cost for the UGW have been evaluated.