Reason analysis on the abnormal oil dissolved gas for high voltage CT

This paper analyzed the abnormal oil dissolved gas on high voltage CT in power system. Through analysis, it indicated that: both electrical fault and non-electrical fault can cause abnormalities of oil dissolved gas and the corresponding solution was provided respectively. It was the first time to analyze the X wax in insulation layer of the high voltage CT and concluded that: the X wax which existed in oil-filled CT resulted from the partial discharge between the insulating layers. The amount of gases produced such as CH₄, H₂, etc from theoretical analysis and the measured results was consistent. This conclusion provided a theoretical basis to correctly handle the fault of a local CT.