Discharge Characteristics in Simulated Treeing Channel and the Partial Discharge Induced Breakdown of the Polypropylene Film

Abstract

In this paper, discharge characteristics in a simulated treeing channel have been clarified and relationship between an electric breakdown and a superstructure of PP films in a composite insulation simulated treeing channel model have been clarified on the basis of this characteristics. The following are these results.
1. The discharge voltages in a simulated treeing channel increase with channel lengths and decrease with specimen temperatures. Moreover these are higher than one in tungsten-plate electrode system.
2. In the case of a simulated treeing channel on the boundary between spherulites, the electric breakdown occurs in only boundary under DC and impulse applied voltage. In this case, properties of the electric breakdown are good according with the discharge characteristics in a simulated treeing channel.
3. In the case of a simulated treeing channel on a spherulite, the electric breakdown occurs in only spherulite under impulse applied voltage. However, for smaller specimen temperatures than 60°C under DC applied voltage, the degeneration area extend to the boundary is recognized, and the electric breakdown occurs in the boundary. For larger than 60°C, many small electric breakdown points and a bigger Point were recognized in the spherulite. In the case, electric breakdown voltage are higher than one given by case of a treeing channel on the boundary under various channel lengths and specimen temperatures.