Contamination Flashover of HVDC Insulators. Final Report

摘要

An integrated field and laboratory study was conducted to investigate the mechanism of flashover of contaminated insulators under HVDC conditions. The field testing rack, constructed at the Sylmar Converter Station, is directly energized by the Pacific HVDC Intertie. Salient factors identified in the field studies were reproduced under simulated conditions in the laboratory for in-depth studies. Effects of each factor were studied one at a time using a highly controllable laboratory testing procedure. Newly discovered phenomena which occur during the flashover process, such as formation of clean zones and the deleterious effect of nitrates on insulating materials, were observed. Theories were formulated to explain the mechanisms involved in these phenomena. Electrochemical properties of contaminants and their effects on flashover process were examined. The relationship between single-component salts and multi-component salts was investigated. Voltage distribution along a string of insulators was studied. New insulator designs using capacitive grading were proposed. Advantages offered by new insulating materials were exploited. New designs showed promising results in both computer analysis and initial laboratory studies. (ERA citation 06:033282)