Studies on Electrolytic Corrosion of Hardware of DC Line Insulators

Electrolytic corrosion of suspension insulator hardware is a wellknown problem with HVDC lines. The development of sacrificial zinc sleeved insulators to minimize these problems and the in-service experience with them is described. This experience is based mainly on the operation of the ±250-kV HVDC transmission line in New Zealand but includes information from the USA and Japan. The paper also refers to detailed investigation into the mechanism of electrolytic corrosion of DC insulator hardware and the possibility of developing an improved insulator for use in areas where contamination is very heavy.