Study on a New Method of Checking the Actual UV Photon Number of Substation Electric Apparatus

As an effective approach of testing corona discharge, UV imaging technology is non-contact, sensitive and intuitive, thus with a bright application prospect in the fault detection of electric apparatus. Currently, the strength of corona discharge is usually represented by the photon number output by UV imager, but in field service, it is difficult to accurately determine and quantitatively control the measuring distance. As a result, the different detection results of photon number are less comparable. This paper first deduces the relationship between the image height of substation electric apparatus and the actual number of UV photons by establishing a model for actual UV photons calculating, and then obtains the statistical results of UV photons of insulators and grading rings in time of different measuring distances and image heights by conducting the field UV corona test. Finally, a new method of checking the actual photons of UV corona is proposed according to the proposed model and field test data. According to the research results, the checking of actual photon number after taking the image height of electric apparatus into account may effectively eliminate the impact of measuring distance during field UV detection.