Flow electrification phenomena employing co-axial cylinders

To date, dozens of failures of large forced oil cooled power transformers have been attributed to flow induced electrification phenomena. The aim of the study is to evaluate the influence of various operational factors on the flow charging characteristics of the oil, by simulating some of the practical configurations. The investigation has revealed that the flow charging of the oil increases with flow rate, ageing and energisation. It also depends on the nature of the oil and the composition, type and surface conditions of the pressboard insulation employed.