Particle-Initiated Breakdown in Gas Dielectric Cable Insulation Expanded Scope Program. Final Report

摘要

The adverse influence of conducting particle contaminants in gas-insulated power apparatus was investigated in a series of experiments that employed coaxial configurations and dc voltages to 1500 kV. Particle dynamics was shown to be important and related to breakdown initiation in the gas. Both SF sub 6 and N sub 2 gases at pressures from 1 to 14.6 atm absolute were used. The particles were intentionally introduced and ranged from 1.6 to 6.4 mm spheres and wires. Effects in the gas gap as well as along surfaces of solid insulators were studied. Visual observations, photographs, and electrical measurements helped in distinguishing various processes. Particles could reduce the insulation performance by factors of 3 to 5 and were especially significant when moved to the center conductor. By coordination of this work with a separate study at the Westinghouse R and D laboratory, a comparison between dc and ac performance was made. Generally the dc breakdown values exhibited wider scatter, though their lower limit was similar to that found under ac. Overall fundamental forces and processes which involve particle contamination effects were identified and found to be the same for dc and ac voltage stresses. (ERA citation 05:015703)