Since the advent of vacuum interrupter, it has been developing towards miniaturization, high reliability and low cost. With the expansion of the application scope of vacuum switch, vacuum interrupter also has a new development direction.
1. Miniaturization
The development of vacuum arc theory and the optimization of internal electric field make the vacuum interrupter smaller;
The application of composite insulation technology greatly reduces the structural size of vacuum interrupter;
The improvement of mechanical characteristics of vacuum circuit breaker, synchronous breaking technology and the application of high-performance contact materials make it possible to “upgrade” and use the vacuum interrupter.
The miniaturization of vacuum interrupter has been carried out for many years at home and abroad, and has achieved certain results. For vc2 vacuum circuit breaker newly developed by German calor Emag company, the contact diameter of 12kV and 20KA vacuum arc extinguishing chamber is only 40mm, and the contact diameter of 12kV and 50kA vacuum arc extinguishing chamber is 80mm.
The volume ratio of the third generation vacuum interrupter newly launched by AEG company * in Germany is reduced to 1 / 3 of the original product.
Toshiba has successfully developed Sade technology. The volume of vacuum interrupter using this technology is only half of that of products with coil contact structure.
2. Low cost
The miniaturization of vacuum interrupter ensures the possibility of low cost. In the past 20 years, the volume of domestic vacuum interrupters has been reduced by 50% and the price has been reduced by about 70%. Among them, the efforts of manufacturers to improve the process level (such as the universal adoption of primary sealing and discharging process), improve production efficiency and reduce production cost are also closely related to the reduction of the cost of parts such as contacts, bellows and ceramic shell.
3. High voltage
With the continuous improvement of vacuum switch manufacturing technology and theoretical research level, the development of vacuum switch has been trying to develop in the direction of high voltage and large capacity. General Electric Company of the United States produced 168kv / 40ka double break vacuum circuit breaker after 1980. Mingdianshe company of Japan began to produce 145kV / 31.5KA single break vacuum circuit breaker in 1980. Toshiba company of Japan successfully developed 145kV / 31.5KA single break vacuum interrupter and 168kv double break vacuum circuit breaker in 1987. In addition, Mitsubishi Corporation of Japan has successfully developed 270kv single break vacuum interrupter and is preparing to develop 500kV Double break vacuum circuit breaker. Once successfully developed, it is estimated that its cost is lower than that of sulfur hexafluoride circuit breaker with the same voltage level. At present, 126kV vacuum circuit breakers developed by Beijing switchgear factory and Xi’an High Voltage Switchgear Factory (all adopt Japan mingdianshe vacuum interrupter) have passed all type tests and completed appraisal at one time.
4. High current
Due to the large rated working current of the circuit breaker for generator protection, it is difficult to meet the temperature rise requirements for the vacuum circuit breaker. At the same time, due to the high rise rate of transient recovery voltage after short-circuit current breaking, it is required to have a higher medium recovery speed. Therefore, the use of this aspect has been limited. However, in recent years, great progress has been made in the vacuum circuit breaker and vacuum arc extinguishing chamber for generator protection. At present, 6300A / 80kA vacuum circuit breaker for generator protection can be produced in China.
5. Low voltage
Low voltage switchgear products are the basic components of electrical appliances with large quantity and wide range. As the vacuum switch has the characteristics of explosion-proof and long service life, as long as the price is limited to a certain level, it has a very huge market prospect. German Ximen * * * launched vacuum circuit breaker products with rated voltage of 380V ~ 1140V, rated current of 630A ~ 2500A and rated short-circuit breaking current of 20KA ~ 65ka in 1994. At present, low voltage vacuum circuit breakers and Vacuum Interrupters with 380V ~ 1140V, rated current 1600A ~ 3200A and rated short-circuit breaking current 30ka ~ 80kA have been developed in China.
6. Solid sealed pole (solid sealed vacuum interrupter)
Using APG technology, the vacuum interrupter and other connecting components are fixed into pole columns, which greatly improves the weather resistance of the vacuum circuit breaker, reduces the phase spacing, and makes the structure of the vacuum circuit breaker more compact and smaller; With the application of solid sealing technology, the external insulation level of vacuum interrupter has been strengthened. The height size of vacuum interrupter, especially the size of insulating shell, can be shortened as far as possible. On the basis of internal insulation optimization, the volume of vacuum interrupter can be reduced accordingly. However, the solid sealing technology requires a good combination between the vacuum interrupter and the buffer layer, and between the buffer layer and epoxy resin, without air gap, otherwise it is easy to produce insulation breakdown.
7. Long life
The frequently operated circuit breaker for on-board switch and electric arc furnace requires a mechanical life of 100000 or even 250000 times. With the development of new operating mechanisms such as permanent magnet mechanism, the improvement of bellows manufacturing technology and the optimization of vacuum interrupter assembly process, long-life mechanisms and vacuum interrupters have been developed one after another. Although the vacuum interrupter with 10000 mechanical life has passed the type test, there is still a lot of work to be done in the aspect of long-life vacuum interrupter, First of all, we should ensure consistency. Secondly, we should march towards higher life requirements to meet market demand.
8. Specialization
In today’s increasingly subdivided market, some special switches came into being. In view of the serious harm to the power system caused by the over-voltage caused by the re ignition of the vacuum switch when opening and closing the capacitor bank, it is necessary to develop a special vacuum switch for opening and closing the capacitor bank. Similarly, in ferroalloy plant, the switch used for electric arc smelting furnace requires high insulation level between vacuum switch poles and ground, low overvoltage and long service life due to high operating overvoltage and poor service environment. Therefore, it is necessary to develop new vacuum switch and vacuum arc extinguishing chamber for ferroalloy plant.
Post time: Aug-31-2021