[Inst. Electr. Eng. Japan 1998 International Symposium on Electrical Insulating Materials - Toyohashi, Japan (27-30 Sept. 1998)] Proceedings of 1998 International Symposium on Electrical Insulating Materials. 1998 Asian International Conference on Dielectrics and Electrical Insulation. 30th Symposium on Electrical Insulating Materials (IEEE Cat. No.98TH8286) - Static electrification as an evaluation method of thermal aging in transformer oil