Electrical conduction phenomena through impregnated pressboard submitted to a thermal gradient

For the last twenty years, flow electrification has been suspected to be responsible of failures in high power transformers. In order to understand the phenomenon and to avoid incidents, several research programs have been undertaken in different countries. Our laboratory is involved in one of this program in collaboration with the French Electricity Company (E.D.F.). From this research in terms of velocity, pipe geometry, temperature and moisture content it seems that the transverse thermal gradient play a fundamental role in the process.