Effective lightning mitigation method on unshielded distribution line by using high charge ratings externally gapped line arresters (EGLA)

In this paper, the procedures for evaluating the MV overhead line lightning performance in operation of one of the distribution system operators in Turkey called ADM Electricity Distribution Corporation will be discussed. The historical tripping data and the power outages cost will be analysed, the lightning mitigation measures will be compared and a methodology will be proposed. System operators are often reluctant to apply LSA (Line Surge Arresters) on unshielded since the LSA will be seen as the primary shield against lightning strokes. Tools as Sigma SLP simulation software can be used to determine the optimum LSA configuration but also to determine the min. charge transfer ratings to achieve low failure rates and get the confidence for long-term performance. High charge ratings EGLA (Externally Gapped Line Arresters) will be considered according to the latest standards, practices and developments for such applications. Technical specifications and required testing protocols are mainly in accordance with IEC 60099-8 (Edition 2.0) for EGLA. After installation and completion, this pilot project will be monitored by the distribution system operator (ADM) over 12 months.