Static electrification-chemical methods to suppress the charging behaviour in transformer oils

The phenomenon of electrostatic charge generation due to friction between the flowing insulating liquid and the fixed solid insulation is well known. The increase in power and voltage ratings of transformers has made the static charge phenomenon an important parameter to be controlled to prevent transformer failures due to charge accumulations. To mitigate this problem of charge accumulations and to suppress the developed charge density in transformer oils, different methods, like, mixing low charging oils with high charging oils, use of additives like benzotriazole (BTA) have been suggested in the literature. In this paper, the authors studied the origin and manifestation of static electrification phenomenon of Indian Paraffinic oils by measuring the charge density of transformer oil base stock (TOBS) and oil samples drawn before clay treatment and oils as received in drums. The authors studied different chemical methods to suppress the charge density of oils by using different additives, like, triazoles, tetrazoles, imidazoles and high molecular weight alcohols. The authors also studied the charge suppression by blending oils with linear alkyl benzene (LAB) and processing with different adsorbents like molecular sieves, alumina, and fullers earth