مقاله شکست و تخلیه ترانسفورماتور و مواد کاغذ عایق در نیتروژن مایع

Breakdown and Partial Discharge Characteristics of Transformer Board and Insulating Paper Materials in Liquid Nitrogen

تعداد صفحات: 5

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زبان لاتین

Breakdown (BD) and partial discharge (PD) characteristics of insulating paper and transformer board materials are investigated as cost-effective alternatives to high-price materials like polyimide (PI) or polytetrafluoroethylene and fiber reinforced plastic materials typically used in superconducting devices based on high temperature superconductors cooled with liquid nitrogen (LN₂). Three different cotton and cellulose based insulating papers are tested in LN₂ at atmospheric pressure and compared to synthetic sheet materials and polypropylene laminated paper (PPLP). Additionally, the BD performance and PD characteristics of three different transformer board materials are investigated in LN₂. The results reveal that the paper and board materials have nearly the same or even slightly higher BD voltages in LN₂ in comparison to the values in insulating oil. The pure paper materials with thicknesses of 130 μm have a dielectric strength of 70-90 kV/mm, whereas values of 130-140 kV/mm are measured for PPLP and PI with nearly the same thickness. The dielectric strength of the board materials has a maximum value of 76 kV/mm. In the frame of the investigations, the BD performance of the pure paper materials in LN₂ is not influenced by the water content of the materials, dried and undried specimens have nearly the same BD voltage. Only the PPLP material has a 15% higher BD voltage in the dried state in comparison to the undried state.