Surface breakdown test results of mineral oil and silicone oil with Kraft paper and Nomex

Document Type

Conference Proceeding

Publication Date

1-1-1992

Abstract

© 1992 IEEE. This paper describes a high voltage test procedure for investigating surface breakdown and demonstrates its application. The dielectric strength of the interface of mineral oil and kraft paper board and the dielectric strength of the interface of mineral oil and Nomex board for the described test conditions are found. The tests are repeated with silicone oil substituted for the mineral oil. The test voltages applied were: negative and positive lightning impulse and 60 Hz. ac. Most impulse voltage breakdowns were observed to occur on the tail of the wave, with the silicone oil breakdowns occuring within the initial 15 μS and the mineral oil breakdowns occuring after 25 μs. Average breakdown voltages from measurements on all boards were tabulated. Results show that both oils perform similarity, particularity on low density kraft board and low density Nomex board. Permittivity matching appears to be a factor in the dielectric strength of the interface to impulse voltages. However, for ac voltages, poor resistance to partial discharges may dominate this effect. As expected, electrical breakdowns under positive impulse voltages are generally lower than under negative impulse voltages.

Publication Title

Conference Record of IEEE International Symposium on Electrical Insulation

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