Design of an Integrated Large-Angle Open-Ring Device for In Situ X-Ray Imaging Inspection of Ultra/Extra High-Voltage Gas-Insulated Metal-Enclosed Transmission Lines

Ultra/extra high-voltage gas-insulated metal-enclosed transmission lines (GILs) feature a large shell diameter, compact installation, and limited testing space, which restricts the application of in-situ X-ray imaging detection technology. Therefore, an integrated large-angle open-ring mechanical device, mainly consisting of a fixed open annular bracket and an open rotating ring, is proposed and developed for X-ray inspection of GILs. The assembled complete mechanism maintains a consistent opening angle and position and can be directly pushed into place and wrapped around the GIL unit during detection tasks. Multiple pairs of rollers are employed to form a size-adjustable annular guide rail on the fixed open bracket. The open rotating ring is mounted inside the guide rail to form a bidirectional clamping and rolling constraint structure. Installation bases for imaging detectors are designed on both sides of one end of the open rotating ring, whereas only one base for the radiation source is arranged on the other end. This configuration enables two imaging modes: vertical X-ray transmission and oblique X-ray transmission through the GIL unit. The rotating ring is synchronously driven by a servo motor via a pair of gears and a timing belt, enabling a circumferential swing angle of 220–230°. This device is suitable for X-ray imaging inspection of multi-specification ultra/extra-high voltage GIL. It can effectively avoid imaging obstructions such as flanges and brackets during data acquisition. It possesses good engineering application potential for factory sampling, in-service maintenance and other non-destructive testing scenarios of GIL.