DC Dielectric Characteristic Study on Epoxy and Air Insulation Materials for the Development of MVDC Switchgear

Abstract

This paper deals with the DC dielectric characteristic of an epoxy and air insulation materials for the deduction of insulation design standards for the development of MVDC switchgear. First of all, after the international standards related with DC voltage tests are investigated, the test electrode configurations and the applied voltage conditions are discussed. Based on the investigation of standards, continuous DC voltage test, LI (Lightning Impulse) voltage test, and superimposed lightning impulse voltage test are performed and the results are analyzed about the epoxy and air. In the case of the solid insulation such as the epoxy, the experiment contains the results of the applied time of DC voltage at the insulation material and variable DC voltage levels in order to secure long time dielectric reliability under the operation condition. In the case of the air insulation, the results of superimposed lightning impulse voltage tests are com-pared with the results with those of lightning impulse voltage tests. The results of the experiments show that the applied time of DC voltage doesn't greatly affect the solid and air insulation performance in contrast with XLPE cable because of the characteristic of space charge about the epoxy. If DC voltage is getting higher, the lightning voltage level is identified to be lowered.