Static electrification of the insulating materials used in powertransformers

摘要

It is shown that the electrostatic charge tendency (ECT) is avaluable indication allowing one to evaluate the levels of the chargedensity which can be reached by the oil in a power transformer. Acorrelation can be made between this parameter (ECT) and thephysicochemical and electrical characteristics of the oil. It is shownthat the water migration phenomena at the oil/pressboard interface playan important role in the charge separation. Hence we investigate theinfluence of the rugosity of the pressboard, the temperature gradientsand the ageing of the oil. The effect of the antistatic additives on theageing and the ECT is also considered