Sho Okada, Kazuki Tanaka, Shoko Ishizu, Shusuke Takekawa, Hideki Ueno, Shinya Ohta, Akira Mizoguchi, Masaaki Yamauchi
Lecture Notes in Electrical Engineering 599 LNEE 99-109 2020年 査読有り
© Springer Nature Switzerland AG 2020. The abstract should summarize the contents of the paper in short terms, i.e. 150—250 words. Partial discharge characteristics of new developed foamed wire with various insulated layers with low dielectric permittivity by including small air cavities in insulating layer have been studied. Partial discharge inception voltages (PDIV) have been investigated. PDIV depends on insulation layer of enamelled wire clearly, that is, PDIV for enamelled wire using an insulator with lower dielectric permittivity foamed polyimide becomes higher by increasing air cavities in the insulated layer. Furthermore, possibility of partial discharge generation in air cavities in the insulating layer has been also studied. By theoretical electric field analysis, electric field of each cavity is relaxed lower than that at the gap between wires due to presence of a great number of cavities in foamed insulating layer, resulting in suppression of partial discharge in the cavities. Partial discharge initiates in gap between wires before discharge generation in cavities of the new developed wire. From V - t characteristics measurements, the evaluated lifetime for enamelled wire using foamed wire is improved comparing conventional unfoamed one.