Role of sulphur in transformer oil and its influence on the performance of paper

Paper-oil insulation is widely used in transformers. In recent years, the utilities in India have shown a lot of concern over the allowable limits of sulphur in transformer oil. It is reported that during life cycle of transformer, paper and pressboard insulation undergoes deterioration mainly because of increase in sulphur content in transformer oil. Further, the effect of increase in sulphur content in transformer on the performance of paper and pressboard insulation is also not clearly understood. There is a need for generating data on the limits of sulphur in transformer oil and to define its end point, behind which the oil becomes unserviceable.