Development of miniature circuit breakers with selective protection

Development of small circuit breakers with selective protection: low voltage circuit breakers are mainly used in power distribution networks, which can be used to distribute electrical energy and protect circuit and power equipment from over current (including overload and short circuit) and so on. The ideal mode of power supply is that once the current fault occurs in a certain place in the distribution network, the breaker of the circuit breaker is quickly removed. And not to cause harm to enter...

Low voltage circuit breaker is mainly used in power distribution network, which is used to distribute electric energy and protect circuit and power equipment from over current (including overload and short circuit) and so on. The ideal mode of power supply is that once the current fault occurs in a certain place in the distribution network, the breaker of the circuit breaker is quickly removed. And not to further expand the harm, nor cause the power lines in the series of other circuit breakers without tripping, and affect the power supply.

In 50s and 60s China's first family residential distribution protection is the most knife gate type switch and fuse simple (porcelain plug RC1) assembly. When the short circuit occurs, the entire house was dark, not easy to replace a fuse. At the end of 60s to 70s, China has successively developed DZ5, DZ12, DZ15 series circuit breaker poles. At the end of 70s, the introduction of German technology in Beijing switch factory and the transfer of domestic manufacturers to produce S060 series of small circuit breakers, but for a variety of reasons not to large-scale promotion. In late 80s, Tianjin MGE company produces many manufacturers C45N and domestic production of DZ47 series miniature circuit breaker of large-scale production, I state circuit breakers for overcurrent protection up to a new level.

Since entering the new century, people's material life has been further improved, the application of power distribution system in the residential area of automation and high reliability requirements are getting higher and higher. However, in the practical application process of circuit protection often appear in the result of fault current circuit breaker tripping at the same time even tripping phenomenon. In order to ensure the reliability of power supply and distribution system in the event of a failure to make its influence is reduced to only the fault point range, we should not only improve its performance, but also should study how to improve is connected in series between the supply and distribution network in the upper and lower circuit breaker with mode selective protection.

Selective protection of low-voltage circuit breakers is actually a kind of over current coordination between two or more over current protection devices. It simply is short circuited in the scope of protection appliances next level, over-current fault should be the protective action of the electric appliances are not on the level of protection action, and when the protection of electrical resistmoves on the level of protection appliances to action, to the scope and priorities for.

According to GB14048.2-2008 "low voltage switch equipment and control equipment second parts: circuit breakers" standard, can be divided into the following two:

Full selection: in the case of two series of over current protection devices, the protection of the load side of the device to protect and sometimes do not lead to another protective device over current selective protection.

In the two series: selective overcurrent protection device, protection device load side implementation of protection and not cause overcurrent protection another selective protection device in a given current value and below.

The work principle of the product is:

Under normal operating conditions, the working principle of the main circuit of the selective protection circuit breaker is the same as the general MCB, which is used for overload protection. When a branch fault, effect of electromagnetic core coil of the main loop in the main loop immediately in the moving contact is opened and the electric arc occurs, effectively limiting the short-circuit current, at the same time, the main circuit short-circuit current flowing and auxiliary circuit, auxiliary circuit series a current limiting resistor and selective double sheet metal. The short-circuit current is limited to only a few hundred amperes or so immediately. If the short circuit current is cut off by the MCB of the fault branch of the load side, the main circuit of the moving contact is closed again under the action of the spring, which ensures the normal operation of the other non fault branches after the main switch. If a short circuit occurs between the main switch and MCB or back, and MCB or other short circuit protection device can not cut off the fault circuit, then selective double sheet metal in 10ms ~ 300ms time release release mechanism, make contact and keep in an open position, and cut off the fault circuit.

Some foreign enterprises such as ABB, Hagrid are conducting research in this area, also introduced some products for use in their home, as the main switch family residential distribution, the main idea is that the switch selective overcurrent trip mode, and not merely rely on cooperation between the upper and lower switch to to achieve selective protection purposes.

At present, Shanghai Electrical Appliance Science Research Institute and other two manufacturers have successfully developed a new type of selective protection of small circuit breakers, and has been to the market. Among them, Jiangsu Kchibo electric appliance as a holding subsidiary of Shanghai Electrical Appliance Science Research Institute, is also rapidly developing industrialization process, is expected to be completed in November 2011 to develop the market.

Model with selective protection of small circuit breaker as one of China's fourth generation low-voltage electrical products, completely by technology researchers of China's low-voltage electrical innovation, launched with independent intellectual property rights, technical and economic indicators have reached the international advanced level. The product can effectively solve the tripping phenomenon of premises distribution system, greatly improve the stability and reliability of the terminal power distribution system. Its main features: with selective protection, high breaking capacity