Vacuum Circuit Breakers Have Occurred in High Pressure Field

Vacuum circuit breakers have taken an absolute advantage in the medium voltage field (12-40.5kV), but have also been in the high pressure field (72.5-252kV), 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 have also been continuously developed new products in the 72.5~126kV 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 sets of 72-252kV vacuum circuit breakers.

At present, the high-voltage vacuum circuit breaker has reached 145kV single fracture, 168kV double fracture, is now developing higher voltage grade products. The products are tank-type and porcelain-column in structure. China has made a porcelain pillar type 126kV vacuum circuit breaker, while Japan's 168kV vacuum circuit breaker adopts a tank structure.

In the vacuum arc extinguishing outdoor insulation, low pressure SF6 gas such as (inner charge pressure 0.12MPa) 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 126kV vacuum circuit breaker in 2010, and passed the National Ministry of Science and Technology acceptance. 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 Hannover Fair, Siemens exhibited the use of nitrogen-filled (N2) insulated 72.5kV vacuum circuit breakers to replace the traditional SF6 circuit breakers, which 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.