Title :
Development and practical operation of perfluorocarbon immersed 275 kV transformers with compressed SF6 gas insulation
Author :
Hiraishi, K. ; Uwano, Y. ; Shirakura, K. ; Gotanda, Y. ; Higaki, H. ; Endoo, K. ; Horikoshi, M. ; Mizuno, K. ; Hora, H.
Author_Institution :
Kokubu Works, Hitachi Ltd., Japan
fDate :
4/1/1995 12:00:00 AM
Abstract :
A perfluorocarbon (PFC) immersed 275 kV power transformer with compressed SF6 gas insulation has been under development. This paper clarifies the AC partial discharge inception voltage and time characteristics of PFC immersed insulation and also clarifies that a prototype 275 kV 100 MVA three-phase transformer could be operated without any trouble during long-term overvoltage tests. This prototype proved that it had AC partial discharge inception strength of higher than 1.5 times the AC test voltage and lightning impulse breakdown strength of 1.5 times the test voltage. A 275 kV, 250 MVA three-phase power transformer was developed and operated at the outdoor substation of the Chubu Electric Power Co., Japan. This transformer has been successfully operated to date and a detailed internal inspection of the transformer was carried out after one year and 9 months of successful practical operation. No significant abnormal condition was recognized
Keywords :
SF6 insulation; electric breakdown; electric strength; gas insulated substations; impulse testing; insulation testing; overvoltage; partial discharges; power system measurement; power transformer insulation; power transformer testing; substation insulation; transformer substations; 100 MVA; 250 MVA; 275 kV; AC partial discharge inception voltage; Japan; SF6; SF6 gas insulation; development; internal inspection; lightning impulse breakdown strength; long-term overvoltage tests; outdoor substation; perfluorocarbon immersed insulation; power transformer; three-phase; time characteristics; Breakdown voltage; Gas insulation; Impulse testing; Insulation testing; Partial discharges; Phase transformers; Power transformer insulation; Power transformers; Prototypes; Voltage control;
Journal_Title :
Power Delivery, IEEE Transactions on
