Determination of wax content in mineral paraffinic oils

Mineral paraffinic oils, now considered for replacement of the dwindling naphthenic oils used in transformers produce solid waxes at low temperatures which can have detrimental effects on the transformer life. Since the electrical and chemical properties of both kinds of oil are almost indentical it is very difficult to determine the presence of paraffins in a sample of transformer oil. Several techniques including DSC, X-rays and cloud point measurements were used for this purpose on paraffinic oils of different origins. The best simultaneous evaluation of the onset of crystallization and wax content is obtained by DSC.