Caracterization and Rheological Behaviour of a Used Insulating Oil and a Transformer Sludge

Abstract

It is not always possible to avoid electrical equipment transformer failures even under constant control. At least 80% of transformers failures causes are due to a deterioration of insulating oil in the transformers. The most serious consequences are the ones related to sludge accumulation on the windings and in the solid insulation. This contamination leads to a mechanical insulation failure, which often causes noise at substations, damage to insulating surfaces and partial discharges. A structural characterization and rheological behavior of a sample of the used oil and sludge has been determined.