Static electrification effects in transformer oil circulating pumps

An effort was made to determine whether or not static electrification production mechanisms could be present in the external oil circulating system of a power transformer. Several techniques were utilized. These were monitoring the leakage current from insulated pipe sections and conducting probes introduced into the flowing oil. The value of the charge contained in the oil was determined using a recently developed absolute charge sensor. Acoustic emission detection techniques were also used to detect any partial discharges resulting from significant charge separation buildup in any one location. Although doubts exist about the quality of some of the data obtained, sufficient evidence was collected to show that, under certain conditions, the oil circulating pump could be a significant contributor to static electrification levels in operating power transformers