Outdoor high-voltage vacuum circuit breaker (column vacuum circuit breaker) has an absolute advantage in the medium voltage field (12-40.5kV), and in the high voltage field (72.5-252kV) has also emerged, and its development prospects are promising. In China, medium-voltage vacuum circuit breakers accounted for 99.39% of medium-voltage switches in 2009. The high-voltage vacuum circuit breaker has also been continuously developed at the 72.5~126kV level and has 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, etc. According to statistics, 3,350 72-252kV vacuum circuit breakers have been used in Japan's power transmission system. At present, the high-voltage vacuum circuit breaker has reached 145kV single break and 168kV double break, and is now developing higher voltage level products. The product has a tank type and a porcelain column type in the structure, China has made a porcelain column type 126kV high-voltage vacuum circuit breaker, while Japan 168kV vacuum circuit breaker adopts a tank structure. In the outdoor insulation of vacuum arc extinguishing, low-pressure SF6 gas such as (internal charging pressure 0.12MPa) is used for insulation, and dry pressure air is also used as external insulation.
It is worth mentioning that two mainstream manufacturers of high-voltage switches in China have newly developed porcelain column vacuum circuit breakers, such as the 126kV vacuum circuit breaker of the Ministry of Science and Technology project successfully completed by Xidian Company in 2010 and passed the acceptance of the Ministry of Science and Technology. The arc extinguisher of this product adopts a longitudinal magnetic field coil structure and uses a copper-chromium contact material with high breaking capacity and good resistance to welding. The vacuum interrupter developed by the supporting facilities is the first product with intellectual property rights completed in China, and its technical level is at the level. The other is Pinggao Group, which has lost no time in developing high-voltage and large-capacity SF6 circuit breakers while also losing no time in developing high-voltage vacuum circuit breakers. In November 2011, the group simultaneously carried out the national appraisal of four new products: LW55-72.5 tank SF6 circuit breaker, ZW55-63 high-voltage vacuum circuit breaker, ZW55-2× 31.5 and ZW55-31.5 vacuum circuit breaker, and the overall level has been reached.
At the Hannover Messe 2011, Siemens exhibited a 72.5kV vacuum circuit breaker insulated with nitrogen (N2) to replace the traditional SF6 circuit breaker, which shows that Siemens has begun to focus on the research and development of outdoor high-voltage vacuum circuit breakers. At high voltage levels, the development of vacuum circuit breakers is the need of the development of the situation, which can greatly reduce the use of SF6 greenhouse gases, which is conducive to environmental protection and reduces the greenhouse effect in the atmosphere. At the same time, the high-voltage vacuum circuit breaker has good low temperature resistance, which can avoid the problem of SF6 gas liquefaction in alpine areas, and is a good choice for high-voltage level circuit breakers in alpine areas. 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 interrupting, rated current and temperature rise, mechanical characteristics, vacuum arc extinguishing outdoor insulation and capacitive current interrupting, small inductive current interrupting, etc. The solution of these technical problems has promoted the progress of vacuum circuit breaker technology. However, the development of outdoor high-voltage vacuum circuit breakers is in the ascendant, and research work is still needed.
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