Application of Leakage Current Monitoring in Design of HVDC Insulation
As part of past uprating of its HVDC link and reinsulating the line for 350 kV, Transpower initiated a program to collect pollution data at various points. ESDD was measured on energized insulators and pollution flashovers tests carried out to establish relative performance of different insulator types. During the past years, silicone and RTV silicone coated glass insulators have been considered to improve pollution performance of insulators in coastal areas. This presentation reviews service experienve with different insulators. It also explains how monitoring leakage current on coated glass insulators has allowed assessing wether hydrophobicity can allow reduce creepage distance of strings by correlating data from field studies with the approach of IEC 60815-4.