Performance of coated GIS conductors under impulse voltages

Particle charging under impulse voltage and particle position instability were investigated for coated gas-insulated system conductors. A contaminating particle is subject to position instability when the electrostatic force applied equals its weight. The effect of dielectric electrode coating under impulse voltages is insignificant when the resistivity of dielectric material is less than 10/sup 9/ Omega m. When the applied impulse voltage on the system is higher than the instability threshold, the particle's accumulated charge decreases drastically and the particle tends to lift off earlier, posing more danger to the system. When the applied impulse voltage on the system is higher than the instability threshold, the effect of the relative permittivity on the accumulated charge appears to be negligible while that of the coating resistivity seems to be insignificant.<>