Computer analysis of transmission line insulation for lightning performance

The authors describe a transmission line lightning performance analysis program, QCORTL, which is able to predict single and multi-circuit flashover and outage types and rates of a quadruple circuit transmission line. They employ the Monte-Carlo statistical technique to select lightning and system parameters from their probability distributions and the dynamic travelling wave technique to calculate overvoltages on transmission line towers. The program also incorporates nonlinear corona effects, the dynamic response of soil and the modelling of wooden-crossarms for arc-quenching in its calculations. The program gives relevant information of crossarm behaviour and reveals weakness which a transmission line designer can then correct. The capability of the program is illustrated by the analysis of a few Malaysian transmission lines. Some pertinent design points are derived