Developing separate-cooling/sheet-winding gas-insulated transformer

Muramoto, H.; Yamazaki, T.; Murakami, Yasushi; Yanari, Toshiyuki; Ikeda, Masami; Ōkubo, H.; Togawa, Yoshiaki

doi:10.1109/61.193888

Cited by 21 publications

(2 citation statements)

References 5 publications

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“…However, since it is very difficult to realize non-flammable, extra high voltage large power transformers with only SF6 gas insulation, a new type of non--flammable power transformer is required. Non-flammable transformers, in which the roles of transformer cooling and insulation are complete1 separated, have been conceptually presented(' ) ( 2 f 7 and trial produced (3). In these transformers, Freon or another fluorocarbon was used for transformer cooling and SF6 gas was used for insulation.…”

Section: I~o W C T I O Nmentioning

confidence: 99%

Basic insulation characteristics of perfluorocarbon for large power transformers

Takagi

Higaki²,

Endoo³

et al. 1988

IEEE Trans. Power Delivery

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To evaluate performance of non-flammable high voltage large power transformers, the effects of pressure and dissolved SF6 g,as on the AC and lightning impulse insulation characteristics of perfluorocarbon were studied. With current flows of up to 300A in the conductor of an inter-coil insulation model, phenomena relating to SF gas bubble release from the conductor surface were studied. Then, relationships between the bubble release phenomena and the basic insulation characteristics of perfluorocarbon were clarified. I~O W C T I O NIn recent years, demands for non-flammability of power apparatus in urban area substations have been increasing in Japan. This is due to the employment of more underground substations in buildings and programs to introduce extra high voltage power systems in crowded urban areas. As such, there is a growing tendency to use SF6 gas insulated transformers or dry-type transformers instead of relatively small capacity, oil-immersed transformers. However, since it is very difficult to realize non-flammable, extra high voltage large power transformers with only SF6 gas insulation, a new type of non--flammable power transformer is required. Non-flammable transformers, in which the roles of transformer cooling and insulation are complete1 separated, have been conceptually presented(' ) ( 2 f 7 and trial produced(3). In these transformers, Freon or another fluorocarbon was used for transformer cooling and SF6 gas was used for insulation. Other new non-flammable power transformers with two-phase cooling, which are wholly insulated with SF6 gas and sprayed with fluo T%~@J. liquid for cooling, have also been trial made Perfluorocarbon is an excellent coolant with non-flammability which additionally has good insulation properties. Therefore, transformers insulated with perfluorocarbon should be desirable. A two-phase insulation of perfluorocarbon liquid and SF6 gas would be advantageous, because perfluorocarbon is very expensive. Consequently, the basic insulation characteristics of perf luorocarbon (C8F1 6O as the main component) are investigated in this paper, including the influence of the existence of dissolved SF6 gas. The following subjects are considered.(1) The boiling point of perfluorocarbon is as low as 100OC at atmospheric pressure. Since the insulation strength of the vapor phase is much lower than that of liquid phase, no boiling of perfluorocarbon necessitates an increased pressure on the liquid surface.58 CPl 048-1 oy t h e IEEE T r a n s f o r n e r s C o l n i t t e e of t h e I E F E Power E n g i n e e r i n g S o c i e t y f o r p r e s e n t a t i o n a t t h e IEEE/ PES 1185 Winter Y e e t i n g , New York, *Jew York, J a n u a r y 31 -F e b r u a r y 5 , 1988. M a n u s c r i p t s u b m i t t e d August 28, 1 9 5 7 ; made a v a i l a b l e f o r p r i n t i n g December 2 , 1987. 4 n a p e r recommended and approved Therefore, it is necessary to clarify the AC an3 lightning impulse insulation strength of perfluorocarbon at elevated pressures of the liquid.(2) When SF^ gas is ...

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Section: I~o W C T I O Nmentioning

confidence: 99%

Basic insulation characteristics of perfluorocarbon for large power transformers

Takagi

Higaki²,

Endoo³

et al. 1988

IEEE Trans. Power Delivery

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“…Thus, it is very important to address the issue of the creepage discharge properties on solid dielectrics with the surface charge; especially it is strongly required to quantitatively understand them. These analyses would be also very important for SF6 gas transformer insulation in which PET films are used as main insulator in SF6 gas [2] .…”

Section: Membermentioning

confidence: 99%

Creepage Discharge Propagation on Charged Dielectric Surface in SF<sub>6</sub> Gas and Its Optical Observation

et al. 1995

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Development of personal‐computer‐based high efficient technique for electric field optimization

Katō

Hikita

Hayakawa

et al. 1995

Int Trans Elec Energy Syst

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We have already developed a personal-computer-based electric field calculation system combined with CAD (Computer-Aided Design); the system is referred to as "CADEF '' (CAD with Electric FieldAnalysis). This system utilizes a charge simulation method, and enables us to realize the automatic calculation of the electricfield. This paper describes the results of the newiy developed electricfieid optimizing process which is added to "CADEF". To achieve a more efficient optimizing routine, we introduce a new algorithm to determine how to arrange the optimization charges into the region to be optimized: both positive and negative charges are assigned at the same time in the calculation step to enhance its convergence and the variety of electrode-contour modification.

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Developing separate-cooling/sheet-winding gas-insulated transformer

Cited by 21 publications

References 5 publications

Basic insulation characteristics of perfluorocarbon for large power transformers

Basic insulation characteristics of perfluorocarbon for large power transformers

Creepage Discharge Propagation on Charged Dielectric Surface in SF<sub>6</sub> Gas and Its Optical Observation

Development of personal‐computer‐based high efficient technique for electric field optimization

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