Establishing a lightning protection evaluation program for distribution and subtransmission lines

Union Electric (UE) began a project in December 1994 to evaluate the performance of existing types of lightning protection, identify deficiencies, and recommend changes that will result in improved performance. UE employs two basic types of lightning protection-static wire and arresters. The authors discuss ground impedance, the National Lightning Detection Network, and the Lightning Protection Design Workstation (LPDW). The LPDW is a Windows based software package developed by EPRI to assist in designing an optimum protection scheme. The first step in the evaluation process is to identify lines that have historically performed poorly under lightning conditions. The next step is to conduct pole-by-pole field inspections of the feeders to identify what factors were contributing to the poor performance of each line. Once it is determined that a feeder is in need of improvements and the deficiencies are identified, the LPDW is used to compare alternatives. Two case studies are discussed.