Lightning Protection of the Overhead Transmission Lines Long Spans Without Ground Wires by Using Line Arresters

In this paper is analyzed lightning protection of long spans of overhead transmission lines (OHLs) which are not protected with ground wires. Such spans are typical at rivers crossings, where ground wires are removed to reduce mechanical stress of the OHL towers and their footings. OHLs with rated voltages of 110 kV, 220 kV and 400 kV are analyzed in this paper. To reduce the number of OHL trips outs caused by lightning strikes to the unprotected spans, line arresters (LA) can be installed in all phases of the two adjacent towers of the span. In that case there is no possibility of flashovers at line insulators. However, there is still a small probability of span flashovers although LAs reduce possibility of such events.