RISK ASSESSMENT BASIS OF MOVING PARTICLES IN GAS-INSULATED SUBSTATIONS

Comprehensive acoustic measurements on bouncing particles in a GIS hav e been carried out. The objective is to find parameters that both are available from external acoustic measurements and usable for assessing whether a particle has the potential to cause an insulation breakdown , The elapsed time between subsequent particle impacts is a measure of how far into the high-field region the particle can move, and thus al so a measure an criticality. Secondly, the amplitude of the acoustic s ignal generated as a particle impacts the enclosure increases with inc reasing particle length and thus also with increasing criticality, Mor eover, plotting Obese two parameters against each other ('particle fli ght time' vs, 'signal amplitude at impact') for a significant number o f impacts (e.g. 1,000) always yields a very characteristic pattern, wh ich in itself is a strong indication that the recorded signals are gen erated by one, moving particle.