Breakdown Voltage in Particle Contaminated Compressed Gases

A method for calculating the breakdown voltage in particle contaminated compressed gases is proposed in this paper. The method is based on the streamer breakdown criterion. It is assumed that at breakdown voltage, the gap between the particle and the bottom electrode breaks down first, which electrically shorts the particle with the bottom electrode, and then a critical avalanche develops at the top of the particle to cause the complete breakdown of the main gap. Calculations are made for spherical particle in parallel plane electrodes containing SF6 and N2 at pressures varying from 1 to 5 atm (0.1 to 0.5 MPa) absolute. The agreement between the calculations and the experiments is reasonable at lower pressures but at higher pressures the experimental values are lower than the calculated values.