Flow electrification in power transformers: temperature influence on spacecharge distribution and charge accumulation in pressboard

Static electrification has been suspected to be at the origin of serious in cidents in power transformers. In fact, the oil flow electrification phenom enon in power transformers induces charge accumulation in pressboard and th en increases its surface potential. In some unknown conditions, this potent ial can induce some electrical discharges and then serious failures in powe r transformers. This paper presents the results, which are one part of a wo rk made in the L.E,A. for the best understanding of this problem. The influ ence of the temperature gradient on the space charge distribution and accum ulation in the pressboard is studied by two special set-ups performed in th e laboratory. Also, it seems that temperature increases charge accumulation magnitude inside the pressboard, but the charge distribution deep in the p ressboard seems to be non dependent of gradient temperature. (C) 2001 Elsev ier Science B.V. All rights reserved.