Time constant evaluation of transient AC – DC field distribution

Summary

This paper focuses on the time constant of transient AC – DC field distribution of DC GIS. As the resistive field depends on the conductivity of solid insulation and surrounding gas in the GIS, these parameters need to be assessed. Therefore, the physics of nonlinear conduction in the gas is considered as a result of natural charge generation by radiation and recombination. The time constant of the system is then evaluated using a simulation model that takes into account a gas model and the surface and bulk conductivities of solid insulator. The influence of different parameters, such as the nonlinear conductivity, the shape and dimensions of the solid insulator, are then investigated. Variations of the surface and bulk conductivity of solid insulator with dependency on the electrical field and temperature can reduce strongly the time constant for usual field conditions in GIS. Simulation results presented give a better understanding of the AC – DC field transition under DC stress for two typical shapes of solid insulators in GIS, disk and conical, and they can guide for the definition of DC GIS tests procedures by considering realistic time constants.

Additional informations

Authors

Chmura Lukasz Andrzej, Gunaltay, FUJIMOTO, Gorokhov