Preliminary investigations for the retrofilling of perchlorethylene based fluid filled transformer

The main results from investigations aiming into the retrofilling conditions of a transclene (perchlorethylene based liquid) filled transformer are presented. The investigations were carried out on insulating liquids with less environmental risks than perchorethylene (Perc) but of almost similar electrical properties which were a mineral based transformer oil and a synthetic ester liquid. Also the influence of a small detachment of hydrochloric acid (HCl), which could be formed by Perc and water during operation is discussed. It has been generally acknowledged, that the life of an insulating liquid in service depends primarily on its initial quality, but service conditions need to be considered too. Additionally, the influence of aging was investigated. A comparison of the measured data with the pre-determinations of the relevant standards and the consequences for the use of the mixtures in transformers are presented.