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On August 8, a groundbreaking vacuum-based fast-acting circuit breaker rated at 363kV / 5000A with an opening time of just 1.2ms was successfully tested in Xi'an, Shaanxi. Developed by State Grid Ningxia Electric Power Co., Ltd., the device passed a critical breaking test with a short-circuit current of 80kA, marking a major milestone in power system technology.
This fast-acting circuit breaker is designed to enhance the safety and stability of power grids. As a bus-coupling circuit breaker, it allows parallel operation of busbars under normal conditions, ensuring system reliability. In the event of a nearby busbar short-circuit fault, the device rapidly divides the current within one cycle, significantly reducing the impact on the grid. This innovation effectively addresses the issue of excessive short-circuit currents, which can otherwise damage equipment and disrupt operations.
Moreover, the circuit breaker quickly isolates fault currents in a single cycle, improving overall system stability and preventing cascading failures that could lead to large-scale outages. By minimizing the fault current, it reduces stress on other grid components and lowers the need for costly infrastructure upgrades. Additionally, as a key component in new energy stations and sensitive load lines, it swiftly removes faulty circuits, preventing production halts and product losses in critical industries.
The project, initiated in 2016, aimed to address serious issues with short-circuit currents in ultra-high voltage grids, which posed risks to grid safety and economic efficiency. The development of this 363kV/5000A/63kA fast circuit breaker involved collaboration between State Grid Ningxia Electric Power Co., Ltd.'s Electric Apparatus Research Institute and several leading institutions, including Nanrui Group, Anhui Huidian Technology, and universities like Xi'an Jiaotong and Chongqing University.
Through extensive research, the team mastered essential technologies for fast circuit breaker design and control. This achievement not only promotes the growth of the high-voltage circuit breaker industry but also strengthens national technological independence and manufacturing capabilities. It supports the construction of smarter, more reliable power grids and brings significant social and economic benefits.
(Original title: The world's first 363kV/5000A fast vacuum circuit breaker achieved key technical breakthroughs)
July 25, 2025