In modern society, no matter in industry, agriculture, transportation, national defense, culture, education and health, finance, commerce, tourism service and people's life and other fields, electricity is indispensable. Power distribution is an extremely important link in the generation, transmission and use of electricity. The distribution system includes transformers and various high and low voltage electrical equipment, and the low-voltage circuit breaker is a widely used electrical equipment.
The earliest circuit breaker in the world appeared in 1885. It is a combination of knife switch and overcurrent release. In 1905, the air circuit breaker with free tripping device was born. Since 1930, with the progress of science and technology, the discovery of arc principle and the invention of various arc extinguishing devices, the current mechanism has gradually formed. At the end of the 1950s, the rise of electronic components, and the emergence of electronic release, to today, due to the popularity of miniaturized computers, and the emergence of intelligent circuit breakers.
Before the liberation of China, there was almost no circuit breaker manufacturing industry. After the founding of new China, the electrical industry had a great development. The low-voltage circuit breaker experienced four generations of development process. The first generation is the dw1 and dw2 (rated current 200-1500a) imitating the A15 and a2050 of Jiangsu Province; the second generation is the DW10 series updated on the basis of the dwo designed by China in 1958, with rated voltage of AC380V, dc440v and rated current of 200-4000a; the third generation is the DW15 and dwx15 (current limiting type) developed in the late 1970s and put into production in the early 1980s; the fourth generation is the DW45 intelligent universal circuit breaker developed in the early 1990s Device.
In the early and middle 1980s, China successively introduced ah and me type universal circuit breakers from Japan and Germany.
DW45 series universal circuit breaker has the level of similar products (F series of ABB company, M series of Schneider company and AE series of Mitsubishi company) in the international 1990s. It has three section protection features of overload long time delay, short circuit short time delay and instantaneous action, single-phase ground fault protection and intelligent functions of current, action time adjustable, display, test, thermal memory, fault memory, load monitoring, self diagnosis, MCR (low multiple short circuit closing protection) communication interface of protection features.