Author_Institution :
LEMD, CNRS, Grenoble, France
Abstract :
For pt. I see ibid., vol. 9, no. 1, p. 84-91 (2002). Presents a study of streamer inception in transformer oil, in a "semiuniform" geometry under impulse voltage. This geometry consists of parallel plane electrodes, with a thin triggering point of calibrated size emerging at the center of one plane. By reducing the length of the point, it is possible to move progressively from a point-plane geometry, up to a quasi-uniform geometry. Compared to a point-plane gap, the initiation of streamers is impeded due to the presence of a metallic plane behind the triggering point, that reduces the tip field. Field calculations allow to extrapolate the results obtained to the case of microscopic surface protrusions and particles. It is possible to predict the streamer initiation voltage, and hence the breakdown voltage under uniform field, from the shape of the protrusion and from streamer initiation fields measured in point-plane geometry
Keywords :
discharges (electric); electric breakdown; electrodes; transformer oil; breakdown voltage; calibrated triggering point; flat electrode; impulse voltage; metallic plane; metallic protrusion; mineral transformer oil; parallel plane electrodes; point-plane geometry; quasi-uniform geometry; semiuniform geometry; streamer initiation; Electric breakdown; Electrodes; Geometry; Microscopy; Minerals; Oil insulation; Petroleum; Shape measurement; Surface impedance; Voltage;
