Ground icing will influence the safe operation of overhead transmission line in medium and heavy icing areas

and ground wire deicing is particularly important. DC ice-melting is one of the effective measures to remove icing of overhead transmission line

and ground wire insulation is the precondition for DC ice-melting. After insulation

ground wire’s electric performance must meet the conditions of normal operation

ice-melting operation

and lightning protection of transmission line. This paper takes ground wire of 500 kV Weiganjia transmission line for example to introduce the insulation way

and to discuss the electrical performances of the insulator and insulator gap after ground wire insulation. The simulation software EMTP is adopted to analyze the relativity between breakdown of ground wire insulator gap and lightning current amplitude. The protection angles and the lightning trip rates of the Weiganjia transmission line before and after ground wire insulation are calculated

and conclusion is drawn that the lightning protection performance of the 500 kV Weiganjia transmission line changes little after its ground wire insulation for DC ice-melting.