Influence of oil flow quadrupling on electrification phenomena in a shell type transformer
A shell type auto transformer 500 kV/230 kV/35 kV has been equipped with an exceptional set of oil pumps to make possible a test at an oil flow reaching 4.8 times the rated value. On this transformer, electrification tests have been achieved in unenergized and energized conditions to determine the electrification phenomena at this level of oil flow and to measure the safety margin available for the normal transformer operation. During the tests, temperature and dielectric contraints have been adjusted at a value inducing a maximum electrification level. The dielectric strength of the transformer has not been reduced in spite of the increase of leakage currents due to static electrification. No partial discharges could be detected acoustically and the level of electrically measured partial discharges has remained low. Test datas and results of measurement are given in the document. The established very large margin on oil velocity without certainty of reaching a dielectric limit is analysed. It shows that shell type technology of transformers has no particular sensitiveness to electrification phenomena.
- Research Organization:
- Electric Power Research Inst. (EPRI), Palo Alto, CA (United States)
- OSTI ID:
- 96470
- Report Number(s):
- EPRI-TR-105019; CONF-9409355-; TRN: 95:005146-0005
- Resource Relation:
- Conference: Static electrification in power transformers workshop, Milwaukee, WI (United States), 28-30 Sep 1994; Other Information: PBD: May 1995; Related Information: Is Part Of Static electrification in power transformers: Proceedings; PB: 369 p.
- Country of Publication:
- United States
- Language:
- English
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