Surface Defect Detection of GIS Aramid Insulation Pull Rod via Photon Counting

The flashover and breakdown faults induced by surface defects of aramid insulation pull rods (AIPRs) seriously threaten the safe operation of high-voltage gas-insulated switchgear (GIS). To accurately detect the surface defects of AIPRs, this article proposes a high-sensitivity detection method based on the photon counting (PC) technique. The PC characteristics of AIPR samples under different voltages and defect sizes of grounding burrs are investigated, and the influence of defects is also explained by simulation analysis. Results reveal that the defects make the photon number increase sharply, and the increased amplitude is positively correlated with the defect size. The investigation of the feature of photons indicates that it is possible to determine the quantitative relationship between PC results and defect size. In this regard, the PC method provides a new approach for the offline detection of surface defects of GIS AIPRs.

I. Introduction

Gas-insulated switchgear (GIS) is widely used in high-voltage power transmission because of its small footprint, low environmental impact, and high safety [1], [2], [3]. To meet the requirements of voltage level, aramid fiber as a reinforcement material has been more and more widely used in insulation pull rods to improve the insulation and mechanical properties. However, due to the production process and operation, defects, such as air gaps [4], cracks [5], and surface metals [6], may occur in the aramid insulation pull rod (AIPR), finally leading to flashover and breakdown failure. Therefore, improving the defect detection method of AIPRs is of great significance to ensure the safe and stable operation of GIS equipment.