Electric field computation of ±1000 kv dc wall bushing with consideration of space charge effects

Abstract

SUMMARY ±1000 kV DC wall bushing under planning is a complex insulation system which bears the effects imposed by different working conditions. The existence of space charge distorts the electric field distribution, which might result in electric breakdown especially when polarity reversal occurs. Based on space charge theory, the amount of space charge can be calculated. A finite‐element model for ±1000 kV DC wall bushing is established to analyze the electric field distribution under DC, AC and polarity reversal conditions especially considering the space charge effects. The electric field distribution with thermal stress is also calculated in this paper to incorporate the influence of the dielectric temperature gradients. The research results provide useful reference for electric field computation and further insulation optimization in developing ultra high voltage DC wall bushings. Copyright © 2013 John Wiley & Sons, Ltd.

Superhydrophobic Coatings for Improved Performance of Electrical Insulators

“…Dielectric breakdown is a common problem encountered in various electrical apparatus (e.g., power transformers, circuit breakers, power capacitors) . It occurs in insulators when a voltage exceeding the breakdown voltage is applied across the material . Dielectric breakdown arises due to the drastic reduction in dielectric strength (i.e., the resistance of the material to the passage of electric current) and is always accompanied by material deterioration.…”

“…Under an applied voltage, insulating materials can withstand a certain electric field without losing their insulating properties. When the applied electric field exceeds the dielectric strength (the maximum electric field a material can withstand without losing its insulating properties) across the surface, then the material eventually permits the passage of the electric current, which is referred to as dielectric breakdown . The dielectric strength E d is the electric field at the breakdown voltage and is given in Equation as below:where, V bd is the breakdown voltage, and t is the thickness of the insulator over which the electric field is applied.…”