The water impact on the aging of power transformer oil

The paper deals with the aging mechanisms of the power transformer oil insulation. Through the degradation of the electroinsulating paper, a great number of decomposition compounds appears, such as gases, water and solid organic compounds which accelerate the aging process of the mineral oil. As a result of the degradation, redox reactions are developed that amplify the processes of formation of free radicals, or sometimes even of ions that propagate undesirable side reactions in the oil-paper electroinsulation system. The paper analyses the impact of water content on the mineral oil characteristics. The dependence of the breakdown voltage of TR 30 MOL mineral oil on the water content is experimentally obtained, confirming the strongly fall of the electric strength of the oil with increasing of water contents.