China achieves breakthrough in ultra-high voltage circuit breaker technology

On Nov 9, the 800 kV / 80 kA large-capacity circuit breaker, developed by State Grid Shaanxi Electric Power Co, Henan Pinggao Electric Co, and other partners, completed a technical evaluation, reaching a world-leading standard.

The 800 kV / 80 kA circuit breaker sample.

The 800 kV / 80 kA circuit breaker is under capacity testing.

During the development of the 800 kV / 80 kA circuit breaker, the project faced challenges such as a 60 percent increase in short-circuit current energy, a 27 percent rise in recovery voltage rate, and improving the ablation resistance of key components. The team established a high-precision simulation model for the full switching process, built a state-of-the-art arc measurement system to accurately characterize high-voltage, high-current arcs, and developed the world's first 800 kV / 80 kA dual-breaker and arc-quenching chamber.

In addition, they pioneered ablation-resistant graphene contact materials to meet a 20-cycle electrical lifespan and optimized the operating mechanism and buffer structures, overcoming critical challenges in high-capacity switching coordination.

The arc-quenching chamber of the 800 kV / 80 kA circuit breaker.

"The new circuit breaker meets world-leading performance specifications while maintaining the same dimensions as current equipment, enabling direct replacement and upgrades and markedly improving the efficiency and economic viability of grid expansion projects," said Sheng Yong, chief expert of State Grid Shaanxi Electric Power Co. Upon commissioning, the device will significantly strengthen the Northwest Power Grid's capacity to cope with extreme short-circuit currents, safeguard the stability of energy cluster transmission networks, and offer robust equipment support to China's main power grid.