On Dec 14, the transmission inspection team of the State Grid Shanghai Jiading Power Supply Company introduced "X-ray" flaw detection technology for the first time during the acceptance process of the Xingrong 110 kilovolt transmission line project. The company conducted internal flaw detection on the tension clamps of the transmission line to ensure precise inspection.

The project used NY-400/35BG compression-type tension clamps. Different from bolt-type tension clamps, internal defects such as cracks, inclusions, burrs and pores can be detected through visual inspection. These internal defects could lead to local heating, fixture fractures and other faults, posing a serious threat to the safe operation of overhead transmission lines.

"X-ray" flaw detection technology is a non-destructive testing method for internal defects in materials. The principle is that when X-rays penetrate metal materials, the materials have different absorption and scattering effects on the X-rays, creating images of varying darkness on the film.

During the inspection process, operators fixed the X-ray machine to the conductor and aimed it at the inspection site. After receiving instructions from the ground operator sent through the workstation, the X-ray generator recorded the interior of the tension clamp on the film. This is akin to a "CT scan" for the tension clamp.

Acceptance personnel received real-time X-ray images on a monitoring computer and, combined with data analysis, determined whether there were hidden defects such as cracks, off-center cores, or wire strand damage inside the tension clamp. The application of "X-ray" flaw detection technology effectively prevents safety accidents caused by internal material defects and provides a scientific, reliable and quantifiable basis for meticulous acceptance.

Furthermore, the company employed drones and expert comparisons to conduct comprehensive inspections of facilities such as steel pipe pole foundations, bolt fastening, conductors, insulator strings, grounding wires and fixtures on overhead transmission lines from all angles. Inspection personnel controlled drones to take photos and videos of equipment that could not be inspected manually, transmitting them in real-time to laptops. Inspection experts conducted on-site confirmation and comparisons to clearly understand whether the construction quality and process standards met operational requirements. This significantly improved the efficiency and accuracy of the acceptance work.

In the future, the company said it will increase research and testing on advanced inspection methods such as "X-ray" flaw detection technology, expand their application scenarios and deepen the application of three-dimensional acceptance models to ensure the safe operation of transmission lines and promote the high-quality development of the distribution network.