Vacuum circuit breakers occupy an absolute advantage in the medium-voltage area (12-40.5 kV), while they have been exposed in the high-voltage area (72.5-252 kV). Their development prospects are promising. In our country, medium-voltage vacuum circuit breaker accounted for 99.39% of the medium voltage switch in 2009. High-voltage vacuum circuit breakers are also 72.5 ~ 126 kV level continue to develop new products, and has been put into operation. Abroad, many countries and companies are developing high-voltage vacuum circuit breakers, and some products have been put into operation for many years, such as Japan, South Korea, the United States, Germany, Russia and so on. According to statistics, Japan's power transmission system has used 3 350 units of 72-252kV vacuum circuit breakers.
At present, high-voltage vacuum circuit breakers have reached 145 kV single fracture, 168 kV double fracture, is now developing a higher voltage grade products. Products in the structure of cans and porcelain column, China has made porcelain 126 kV vacuum circuit breakers, and Japan's 168 kV vacuum circuit breakers using tank structure.
In the vacuum interrupter insulation, useful low-pressure SF6 gas such as (charge pressure 0.12 MPa) insulation, but also useful dry-pressed air as the outer insulation.
It is worth mentioning that China's two mainstream manufacturers of high voltage switch newly developed porcelain vacuum circuit breakers, such as the 2010 Western Electric Company successfully completed the Ministry of Science and Technology 126 kV vacuum circuit breakers, and through the National Ministry of Science and Technology acceptance. The arc chamber of the product uses a longitudinal field coil structure, using a copper-chromium contact material with high breaking capacity and good resistance to welding. The vacuum interrupter developed by the accessory is the first complete product with complete intellectual property rights in China and its technical level is at the international advanced level. Another is Ping Gao Group, Ping Gao Group in the development of high-voltage high-capacity SF6 circuit breakers, but also seize the opportunity to develop high-voltage vacuum circuit breakers. In November 2011, the Group conducted national identification of four new products, namely the LW55-72.5 tank SF6 circuit breaker, the ZW55-63 high voltage vacuum circuit breaker, the ZW55-2 × 31.5 type and the ZW55-31.5 vacuum circuit breaker , The overall reached the international advanced level.
At the Hannover Messe 2011, Siemens demonstrated the replacement of a conventional SF6 circuit-breaker with a nitrogen-filled (N2) insulated 72.5 kV vacuum circuit breaker, indicating that Siemens is focusing on the development of high-voltage vacuum circuit-breakers.
At the high voltage level, the development of vacuum circuit breaker is the need of the development of the situation, can greatly reduce the amount of SF6 greenhouse gas consumption, is conducive to environmental protection and reduce the greenhouse effect in the atmosphere. At the same time, high voltage vacuum circuit breaker has good low temperature resistance, can avoid the SF6 gas liquefaction in alpine region, and is the best choice for high voltage level circuit breaker in alpine region.
In the development of high voltage vacuum circuit breakers need to solve a series of technical problems are: high voltage vacuum insulation, high current vacuum breaking, rated current and temperature rise, mechanical properties, vacuum interrupter insulation and capacitive current breaking, small inductive current Broken and so on. The solution of these technical problems has promoted the technological progress of vacuum circuit breakers. However, the development of high-voltage vacuum circuit breakers is in the ascendant, and the research work still needs to be vigorously carried out.
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