High-voltage vacuum circuit breaker technology is promising

Vacuum circuit breakers have an absolute advantage in the medium voltage field (12-40.5 kV), but they have also emerged in the high pressure field (72.5-252 kV), and their development prospects are promising. In China, medium voltage vacuum circuit breakers accounted for 99.39% of medium voltage switches in 2009. High-voltage vacuum circuit breakers are also constantly developing new products in the 72.5~126 kV class and have been put into operation. In foreign countries, 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, the Japanese power transmission system has used 3,350 vacuum circuit breakers of 72-252kV. At present, high-voltage vacuum circuit breakers have reached 145 kV single-fault, 168 kV double-fractured, and are now developing higher voltage grade products. The products are tank-type and porcelain-column in structure. China has made a porcelain column type 126 kV vacuum circuit breaker, while Japan's 168 kV vacuum circuit breaker adopts a tank structure. In the vacuum interrupter outdoor insulation, low pressure SF6 gas such as (inner charge pressure 0.12 MPa) is used for insulation, and dry air is also used as the outer insulation.

It is worth mentioning that China's two high-voltage switch mainstream manufacturers have recently developed a porcelain-type vacuum circuit breaker, such as the successful completion of the National Ministry of Science and Technology project 126 kV vacuum circuit breaker in 2010, and passed the acceptance of the Ministry of Science and Technology. The arc extinguishing chamber of this product adopts a longitudinal magnetic field coil structure and uses copper-chromium contact materials with high breaking capacity and good resistance to welding. The supporting vacuum interrupter is the first domestically completed product with complete intellectual property rights, and its technical level is at the international advanced level. The other company is Pinggao Group. Pinggao Group, while vigorously developing high-voltage and large-capacity SF6 circuit breakers, also lost no time in developing high-voltage vacuum circuit breakers. In November 2011, the group also conducted four national product appraisals of LW55-72.5 tank SF6 circuit breakers, ZW55-63 high voltage vacuum circuit breakers, ZW55-2x31.5 and ZW55-31.5 vacuum circuit breakers. , Overall reaching the international advanced level.

At the 2011 Hanover Fair, Siemens exhibited the use of a nitrogen-filled (N2) insulated 72.5 kV vacuum circuit breaker in place of the traditional SF6 circuit breaker. This shows that Siemens began to focus on the development of high voltage vacuum circuit breakers. At high voltage levels, the development of vacuum circuit breakers is a requirement for the development of the situation, which can greatly reduce the use of SF6 greenhouse gases, contribute to environmental protection and reduce the greenhouse effect in the atmosphere. At the same time, the high-voltage vacuum circuit breaker has good low-temperature resistance characteristics, which can avoid the liquefaction of SF6 gas in high-cold areas. It is the best choice for high-voltage circuit breakers in cold regions. In the research and development of high voltage vacuum circuit breakers, a series of technical problems need to be solved: high voltage vacuum insulation, high current vacuum breaking, rated current and temperature rise, mechanical characteristics, vacuum arc extinguishing outdoor insulation and capacitive current breaking, small inductive current Break and so on. The solution of these technical problems has promoted the progress of vacuum circuit breaker technology. However, the development of high-voltage vacuum circuit breakers is still in the ascendant and research work still needs to be vigorously carried out.