氷雪中で起きる局部放電の紫外線画像による電流の大きさの推定

Abstract

In a transmission line passing through a snow region, snow inevitably accretes on insulators more or less and partial discharge might occur on insulator strings covered with snow. Since partial discharge occurring at the surface of polymeric insulator may deteriorate the insulating property of it, it is necessary to find the magnitude of discharge current as well as the location or occurrence frequency of partial discharge to grasp the degree of degradation. The paper shows the method for estimating the magnitude of the discharge current from the images taken by an ultra violet camera. To simulate partial discharge occurring at an air gap in capped snow over an insulator, ac partial discharge was formed between a pair of ice electrodes or snow walls. By increasing applied voltage to the ice or snow electrodes, discharge current was increased. The luminous area in UV image was increased with the magnitude of discharge current below 10mA. The magnitude of discharge current flowing through an air gap formed in accreted snow can be estimated from the luminous area in UV image.