Oil-Flow Electrification Phenomenon in EHV Power Transformers and Restrain Measures

The operating experience of transformer in recent years show that oil-flow electrification have proved to be one of the crucial factors which impact the safe operation of large transformers. For the manufacturing process of extra high voltage transformer become more rigorous than the usual one, relatively, the operating conditions are more severe than before, therefore, effective measures should be taken to prevent the insulation fault caused by the oil flow electrification from occurring, then the operational life of transformer can be prolonged, correspondingly, safe and reliable operation of the power grid could be ensured. Combining the latest achievements from both home and abroad about oil flow electrification phenomenon, for the extra high voltage transformer, this paper make a research on the produce mechanism, influence factor, and find out the specific reasons for oil flow electrification phenomenon in extra high voltage power transformers, and the preventative restrain measures are summarized and put forward. Research results show that the most important measures to mitigate the extent of oil-flow electrification are decreasing flow velocity, optimizing the design of insulation structure, curbing the production of oil charge and realizing for online monitoring.