|
|||||
|
|
AC V-t and impulse V-N characteristics of shell-form transformer insulation model |
|
| Authors: | Shigemitsu Okabe Takahiro Ohno Eiichi Zaima Akio Kishi Kazuaki Aono Noboru Hosokawa |
| Affiliation: | 1. Tokyo Electric Power Co., Inc. Graduated in March 1981 from the Department of Electrical Engineering, University of Tokyo, where he received his Ph.D. degree in 1986. He joined Tokyo Electric Power Co., Inc. in April 1986. He is engaged mainly in research on diagnosis technology and insulation coordination of substation apparatus. He is currently a Senior Researcher in the Electric Power Department at the Engineering Research Center. He received a Paper Award for the I.E.E., Japan in 1993.;2. Tokyo Electric Power Co., Inc. Graduated in March 1988 from the Department of Electrical Engineering, Hokkaido University, where he received his Master's degree in March 1990. He joined Tokyo Electric Power Co., Inc. in April 1990. He is engaged mainly in research on diagnosis technology of substation apparatus. He is currently working in the Electric Power Department at Engineering Research Center.;3. Tokyo Electric Power Co., Inc. Graduated in March 1974 from the Department of Electrical Engineering, University of Tokyo. In June 1990, he received his Master's degree from Massachusetts Institute of Technology. He joined Tokyo Electric Power Co., Inc. in 1974. He is engaged mainly in study and research on substation technology and insulation coordination of UHV, etc. He is currently a Deputy Head of the Electric Power Department at Engineering Research Center. He received a Paper Award from the I.E.E., Japan in 1993. He is a member of IEEE.;4. Mitsubishi Electric Corporation Graduated in March 1970 from the Department of Electrical Engineering, Osaka University, where he received his Master's degree in March 1972. He joined Mitsubishi Electric Corporation in April 1972. He is engaged in research and development of power transformers at the company's Akaho Works.;5. Mitsubishi Electric Corporation Graduated in March 1977 from the Department of Electrical Engineering, Osaka University, where he received his Master's degree in March 1979. He joined Mitsubishi Electric Corporation in April 1979. He is engaged in research and development of power transformers at the company's Akaho Works.;6. Mitsubishi Electric Corporation Graduated in March 1973 from the Department of Electronic Engineering, Kyoto University, where he received his Master's degree in March 1975. He joined Mitsubishi Electric Corporation in April 1975. He is engaged in research and development of power transformers at the company's Akaho Works. |
| Abstract: | To evaluate an appropriate level of ac test voltage for 1000-kV transformers, it is necessary to make an accurate estimation of ac V-t characteristics. For the level of impulse test voltage, V-N characteristics are important to evaluate effects of impulse stress repetition. Since both of the characteristics are dependent on insulation structures and manufacturing processes of transformers, it is important to make accurate simulations on transformer insulation for reliable insulation data. To obtain some of the basic data for 1000-kV transformer test levels, long-time ac V-t tests and impulse V-N tests of up to 1000 times voltage application were carried out on an insulation model simulating fundamental structure of shell-form transformers. The model is composed of a parallel electrodes system with a compound structure of pressboard barrier and oil gap. The tests showed the following characteristics: ac V-t characteristics of up to several ten days could be described by two lines, each representing short-time and long-time characteristics. V-N characteristics of lightning and switching impulse were expressed by relatively flat lines, which showed a decrease in breakdown voltage by less than 10 percent after 1000 times impulse application. |
| Keywords: | Oil-immersed transformer test voltage ac V-t characteristic impulse V-N characteristic 1000-kV transformer |