On the influence of metal deactivators on some properties of transformer oils

The advantages of using metal deactivators or passivators in mineral transformer oils are briefly reviewed. The evidence (from laboratory tests and in service) has demonstrated that they considerably prolong the thermal active life of oils. Metal deactivators can also reduce the static electrification of transformers oils. In addition to increasing the thermal resistance of the oil, they also keep its electrical properties unaltered for a longer period of time and reduce its charging tendency. Although questions have been raised regarding the nature and concentration of metal deactivators as well as their interactions with other additives, none of these questions should impede the use of metal deactivators in transformer oil