Breakdown Characteristics of Combined Insulation in Silicone Oil for Electric Power Apparatus

This paper, investigation of the breakdown characteristics of various combined insulation in the silicone oil as an insulating medium is studied with aim of realization of electric power apparatus, which is considered to be flame-retarding. As the first step, the surface breakdown characteristics of the configuration with triple-junction where the solid insulator is in contact with the electrode are considered from viewpoint of the maximal electric field at triple-junction. As the second step, in order to reduce the amount of the silicone oil used for electric power apparatus, the breakdown characteristics are investigated by the composition in which insulating filler was mixed in the silicone oil. The test is carried out the sphere-sphere electrode of horizontal arrangement and the sphere-plane electrode of vertical arrangement, and relation between the arrangement and size of the filler and breakdown strength is clarified. From these investigations, the optimization of application of the silicone oil to electric power apparatus is considered