Vacuum circuit breaker: the invisible guardian of power safety, decoding the core equipment of modern power grid

  When you enjoy all kinds of power at home for you to bring the service, the use of air conditioning, the breeze of the electric fan, used to make a steamed oven, if suddenly due to short circuit trip, the distribution box will quickly cut off the current device, is the cousin of the vacuum circuit breaker, then you will ask the vacuum circuit breaker? He is in the city's underground substation, is millisecond response speed, guarding the safety of the entire area of power supply, he can identify and cut off up to 100kA short circuit current in 0.02 seconds, equivalent to the instant extinguishing 3000 lightning energy, it is admirable!

According to the International Energy Agency (IEA) statistics, 80% of the world's medium voltage power grid (3-36kV) has adopted vacuum circuit breakers, whose arc extinction efficiency is 4 times higher than that of traditional oil circuit breakers, and annual economic losses caused by arc failures exceed $20 billion. In China, the utilization rate of VCB in the newly built substations of the State Grid in 2024 has reached 95%, and it has become the core equipment of the smart grid under the "dual carbon" goal.

Next, we compare the advantages of vacuum circuit breakers from various angles, and the SF6 circuit breakers and oil circuit breakers should be compared together.

Vacuum circuit breaker arc extinguishing medium: vacuum (<10⁻⁴Pa), breaking capacity (kA) : 40-100, typical life (number of operations) : electrical life of 10,000 times +, environmental protection: no oil.

SF6 circuit breaker arc extinguishing medium: sulfur hexafluoride gas, breaking capacity (kA) : 50-80, typical life (number of operations) : electrical life of 5000 times +, environmental protection: containing greenhouse gases.

Oil circuit breaker arc extinguishing medium: insulating oil, breaking capacity (kA) : 20-40, typical life (number of operations) : electrical life 2000 +, environmental protection: high fire risk.

   By comparison, we can analyze and judge that the vacuum circuit breaker is one of the best! So how is the vacuum circuit breaker to extinguish the arc? First arc generation: contact separation moment, metal evaporation to form high temperature plasma (about 10,000 ° C), current through the arc continuous conduction, and then driven by magnetic field: spiral groove contact produces rotating magnetic field, so that the arc along the surface of the contact high-speed rotation (speed of more than 10,000 RPM), to avoid local ablation. Finally, energy absorption: the shield is made of oxygen-free copper material, rapidly condenses metal steam, and extinguishes the arc when the current passes zero (about 0.01 seconds).

  The vacuum circuit breaker, the loyal defender of the power field, has ensured the stable operation of the power system with its excellent performance and continuous innovative technology in the past decades, profoundly affecting all aspects of our lives. From the bright lights of the bustling city to the electricity protection of the remote mountainous areas; From the efficient production of the factory floor to the continuous operation of the data center, the vacuum circuit breaker is inseparable from the silent protection. With the rapid development of science and technology, we have reason to believe that vacuum circuit breakers will continue to show their skills in emerging fields such as smart grid and clean energy grid connection, and continue to improve performance to contribute to global energy transformation and sustainable development. It is not only an outstanding achievement of industrial manufacturing, but also one of the key technologies to promote the progress of human society, and will write more brilliant chapters in the future. ​