Research and development of the hottest low-voltag

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The research and development of low-voltage circuit breakers should focus on

low voltage circuit breakers (including universal, plastic shell, small plastic shell, residual current protection, etc.) are one of the indispensable and important electrical appliances in the distribution system. The development of low-voltage circuit breakers in China has experienced four stages of imitation (former Soviet Union) and self-design, and has achieved new and greater development in recent years. At present, a large number of new brand products, such as hsm1, DW45, CM1, jm30, jxm1, s series and c45n series, occupy the main part of the market and effectively promote the development of China's national economy. In order to improve the manufacturing level of low-voltage circuit breakers in China and further narrow the gap with the country, it is necessary to develop in the direction of small volume, high breaking, low noise, safe and reliable work and intelligence

while improving the overall level of products, the development focus of various types of products should be focused on:

I. universal (cabinet mounted) low voltage circuit breaker. At present, the economic development in all parts of China is not balanced. From the analysis of market demand, we should develop and improve general universal circuit breakers, such as DW15 series products; We should also develop high-tech products, such as intelligent universal circuit breakers. The former focuses on improving the safety and reliability of products, reducing costs and prices, while the latter focuses on improving and expanding the functions of products

the third generation of self-designed typical products in China are DW45 series intelligent universal circuit breakers. At present, there are four kinds of shell frame current grades that have been mass produced: 2000a, 3200A, 4000A and 6300A. This circuit breaker has the three-stage protection function of overload long time delay, short circuit short time delay and short circuit instantaneous action, as well as the single-phase grounding fault protection function. Its intelligent controller (release) can realize the functions of ammeter and voltmeter; The rated current, setting current and action time are adjustable; Display, test, thermal memory, fault memory, load monitoring, self diagnosis, MCR and communication interface. From the perspective of short-circuit breaking capacity, it can fully meet the requirements of transformer with capacity up to 3150kva and below as main switch (main protection switch)

the future development direction of DW45 series circuit breakers is: 1 Further develop and improve the communication, that is, improve its computer communication function, including the development of new interface appliances, which are connected between the network and the circuit breaker (interface devices such as ast interface module, distributed i/o interface, interface between networks) to serve the computer unit, 4 After the sample is broken, such as bus address encoder, addressing unit and load feedback module. The basic requirements for communicable appliances (circuit breakers) include communication interfaces; Standardization of communication protocols; It can be directly connected to the bus. 2。 It is designed and produced in strict accordance with unified standards. Under the new situation of rapid development of science and technology, the technical requirements for circuit breaker products are becoming more and more strict and complex. Therefore, manufacturers should pay close attention to the development of international standards (such as IEC standards and advanced national standards). At present, great efforts should be made to solve the influence of EMC (electromagnetic compatibility) on circuit breakers

II. Plastic shell circuit breaker. Since the mid-1980s, hsm1 and aluminum alloy cables with good quality have been introduced in China. CM1, tm30, jxm1 and S series products are the foundation. The technical performance of their products is about the international level from the 1980s to the early 1990s. The short-circuit breaking capacity ranges from AC400V, 25ka~ac400v, 85kA, which can generally meet the needs of domestic electric fields

the development direction of molded case circuit breaker in the future is: miniaturization, high breaking, multi-function, modularization of accessories; Intellectualization (including three-stage protection, adjustable current and action time, display, fault memory, load monitoring, communication interface and other functions)

several suggestions for the current domestic development of low-voltage circuit breakers:

1. Rectify the production layout of low-voltage electrical appliances to prevent repeated production and fake and inferior products from entering the market; 2. Strengthen efforts to support enterprises with good conditions to produce high-tech products, and form a pattern of 2-3 leading enterprises in each province; 3. Encourage manufacturers (companies) with development and innovation capabilities to develop 1-2 new products every year to catch up with (learn from) the world's advanced level; 4. Rapidly improve the quality of domestic ferrous metals, chemicals and electronic products, and use the development of low-voltage circuit breakers with high-tech level to drive the progress of other industries; 5. Improve the processing accuracy of circuit breaker parts, vigorously support several specialized manufacturers of parts and components, improve product quality and reduce costs

we can learn from the advanced technology of foreign low-voltage circuit breakers in the following aspects:

1. The intelligent universal circuit breaker accelerates its development to intelligence. At present, the intelligent universal circuit breaker produced by foreign enterprises has become a complete candidate again, such as the construction of CPU units to avoid the maloperation of circuit breakers caused by high-order harmonics, the analysis and measurement of line harmonics, the display of circuit breaker contact wear rate, and the zoneselectiveterlock technology between circuit breakers. At present, the technology of harmonic component measurement and analysis is also available in China, but because harmonics come from electricity and also from the feedback of a large number of electronic devices, it is difficult to fundamentally solve this technical problem (this is a comprehensive problem). Therefore, the measurement and analysis of harmonics do not need to be set for each circuit breaker, and can be supplied as a special accessory according to the needs of users, so as to avoid the impact of multiple harmonics on the performance of circuit breakers and realize the selective Interlocking Technology (ZSI). In these aspects, it is indeed necessary to learn from Huang Shixin, associate professor of Jianxing University of science and technology. At present, foreign companies are more perfect than China in terms of communication protocol standardization. For example, the United States adopts rock well's fieldbus network as DeviceNet, Germany's Siemens adopts PROFIBUS, and France's Schneider adopts jbus. However, our country is still lacking in this aspect, which is still under debate at present

2. Five new technologies should be vigorously promoted for plastic shell circuit breakers:

the circuit breaker fully adopts VJC Technology (vapourcontrol), that is, arc steam injection control technology. After adopting this technology, when the circuit breaker disconnects the short-circuit current, it can greatly increase the arc voltage and prevent the arc from spraying, so that the breaking capacity of the circuit breaker is greatly improved and the volume of the circuit breaker is reduced (for example, the NF series of Mitsubishi Corporation in Japan, the breaking capacity of the circuit breaker with VJC is increased by 1.42 times compared with the circuit breaker without VJC, and the volume is reduced to the original 63.66%)

the contact system adopts double breakpoints and double arc extinguishing chambers, which can greatly improve the short-circuit breaking capacity of the circuit breaker and double its service life

istac Technology (impalsiveslottypeaccelerator-- slot pulsation accelerator) is adopted. After adopting istac technology, the current limiting performance of the circuit breaker can be greatly improved and the space occupied by the arc extinguishing chamber of the circuit breaker can be reduced. The product test of Mitsubishi Corporation of Japan shows that the maximum peak current of its 100A product is reduced to 80%, and the energy CIST through the circuit breaker is reduced to 65%

wall erosion and automatic gas blowing arc extinguishing technology. When the circuit breaker breaks the short-circuit current, the arc temperature reaches 3000~6000 ℃. Under this high temperature, the wall (arc separator) is eroded by the arc and generates gas, which increases the pressure in the arc extinguishing chamber and forms a high-speed flow through the air outlet (hole) to blow out the arc. Gas producing materials include: melamine and phenolic resin, ceramic materials, POM materials, pa6/6 (nylon 66)

develop and apply new silver alloy contacts (add an appropriate amount of rare element additives), which have good arc resistance, fusion welding resistance and low temperature rise

some suggestions: domestic manufacturers or research institutes and colleges and universities with the ability to develop circuit breakers can learn from these foreign new technologies alone or in cooperation. The method is to purchase prototypes of these products for dissection, experiment, analysis and reasoning, and then put them into design and trial production. The new materials needed can be commissioned to domestic metallurgy and chemical industry for trial production. If there are temporary difficulties in development, they can be purchased from abroad

--- China industry news

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