Xuzhou completes first independent 500 kV circuit-breaker protection upgrade

On October 21, the final switching order at the 500 kV Sanbao Substation was executed, marking the successful completion of the State Grid Xuzhou Power Supply Company’s inaugural self-directed 500 kV circuit-breaker protection upgrade.

The project, executed in two stages over a 35-day outage, involved complex tasks such as modifying secondary safety measures and retrofitting switchgear, coinciding with provincial transmission-line construction. This overlap, posed significant technical and safety challenges

To address these, Xuzhou company’s 500 kV Substation O&M and Inspection Centre developed a comprehensive implementation plan. They examined over 40 in-service panels and terminal boxes, meticulously checked cables against schematics, and devisedf more than 150 secondary safety measures, establishing a strong foundation for the project.

The centre also strictly enforced an “on-site presence” system, with high-risk activities like safety-measure implementation and circuit disconnection/connection supervised under a “same-entry, same-exit” protocol. A joint project headquarters facilitated technical briefings and risk management, ensuring no blind spots in interface zones.

“The retrofit was error free,” said Li Ming, head of the secondary section at the 500 kV Substation O&M and Inspection Centre. “This not only demonstrated Xuzhou Company’s capability to independently conduct 500 kV technical reforms but also established a system of precise planning, visualized control, and integrated cooperation, offering valuable insights for future upgrades.”