MODEL APPROACH TO THE STATIC ELECTRIFICATION PHENOMENA INDUCED BY THE FLOW OF OIL IN LARGE POWER TRANSFORMERS.

Static electrification phenomena induced by the flow of oil have been studied using a model duct of a forced oil cooled power transformer. The discharge observed in full scale model transformers at an excessive flow rate of oil was reproduced in the model duct. The leakage current to the ground induced by the flow of oil is a practical measure of the static electrification process. The formula for leakage current obtained from a simple theory based on the separation and relaxation of charges can be applied to explain the static electrification phenomena in full scale model transformers as well as the model duct. The results of this study are applied to assess and control the static electrification phenomena. They contribute to the reliability of insulation in large power transformers.