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

Static electrification has been suspected to be at the origin of serious incidents in power transformers. In fact, the oil flow electrification phenomenon in power transformers induces charge accumulation in pressboard and then increases its surface potential. In some unknown conditions, this potential can induce some electrical discharges and then serious failures in power transformers. This paper presents the results, which are one part of a work made in the L.E.A. for the best understanding of this problem. The influence of the temperature gradient on the space charge distribution and accumulation in the pressboard is studied by two special set-ups performed in the laboratory. Also, it seems that temperature increases charge accumulation magnitude inside the pressboard, but the charge distribution deep in the pressboard seems to be non dependent of gradient temperature.