Study on Corona Activity Using an Image Processing Approach

In the present work, behavior of corona discharges on the polymeric insulating sample, generated from a multiple needle electrode in the presence of normal air and fog (mist) condition, is studied with the aid of an image processing technique. The development of streamers is closely monitored using the high-resolution digital single lens reflection camera. The corona streamers were found to be concentrated in the presence of fog whereas without the fog, streamers spread was wider. A physical model is proposed to explain the observed phenomenon. The obtained digital corona images are processed in the YCbCr color space to effectively extract corona generated plasma using color thresholding method. The streamer spread angle is then calculated by applying the Hough transform technique. The results indicate that streamer spread angle in the presence of fog to be approximately 60% lower than that without fog. Concentrated streamers during fog application are found to damage the polymeric samples more intensely. Scanning electron microscopic (SEM) is conducted on the treated sample and total crack portion is determined by processing SEM images. A linear match is found between the measured surface roughness and extracted crack portion of the treated sample. This paper highlights the possible application of image processing-as one of the tool in analyzing the corona activities and its effect particularly on polymeric insulators.