| Summary: | Severe lightning environment has been the major cause of overhead transmission line outages. In order to minimise the impact of lightning overvoltage, it is necessary to further evaluate lightning performance of any line before implementing specific protection methods. Therefore, in this work, a thorough study on back flashover tripping patterns of a 275/132 kV quadruple steel monopole towers in Malaysia is presented. Several design parameters such as lightning current magnitude, tower footing resistance and power frequency voltage were varied to investigate their influences on the line performance associated with lightning events. The results show that each parameter gives a significant effect on the flashover patterns. For each case, no flashover was recorded on the higher voltage circuits (275 kV), even though the line consists of tall structures, which might be more susceptible to lightning strikes at the upper part. Regardless of the effect of tower height, flashovers occur mainly on 132 kV circuits due to difference in the line insulation level. The results obtained were then used in designing appropriate protection scheme to further improve the transmission line lightning performance, mainly in terms of reducing the double circuit line outages.
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