The world's first circuit breaker emerged in 1885; it was a combination of a knife switch and an overcurrent trip unit. In 1905, the air circuit breaker-featuring a free-trip mechanism-was born. Since 1930, driven by technological advancements, the discovery of arc-extinction principles, and the invention of various arc-quenching devices, the modern circuit breaker structure gradually took shape. In the late 1950s, with the rise of electronic components, electronic trip units were developed; today, thanks to the widespread adoption of microcontrollers, intelligent circuit breakers have made their debut.
Common types include low-voltage circuit breakers and vacuum circuit breakers:
A low-voltage circuit breaker is an electrical device used in circuits with AC voltages up to 1200V or DC voltages up to 1500V to perform functions such as switching, control, or protection. Low-voltage circuit breakers constitute a vital segment of the electrical appliance industry and serve as fundamental supporting components within the machinery sector. In power distribution systems, low-voltage switchgear assemblies are primarily composed of various low-voltage circuit breaker components; consequently, the functionality and performance of these circuit breakers play a pivotal role in the overall operation of the switchgear assemblies. More than 80% of the electrical energy generated by power generation equipment is distributed and utilized through low-voltage circuit breakers. For every additional 10,000 kW of power generation capacity installed, approximately 20,000 various low-voltage circuit breakers are required as components. Furthermore, in industrial automation systems, there is a demand for various control panels, consoles, and controllers-all of which are constructed using low-voltage circuit breakers. Since 1949, China's low-voltage circuit breaker industry has evolved from a foundation of simple factories focused on repair and assembly into a sector capable of independent design and manufacturing. By 1979, the industry boasted over 600 manufacturing enterprises. Following two distinct periods of rapid growth-spanning 1985–1986 and 1990–1991-the number of manufacturing enterprises within the low-voltage circuit breaker industry had reached approximately 1,500 by 1995.
China's low-voltage circuit breaker manufacturing enterprises are primarily concentrated in regions such as Beijing, Tianjin, Liaoning, Shanghai, Jiangsu, Zhejiang, and Guangdong. While contributing significantly to the development of the national economy, this industry structure has also exposed a number of issues. The two most prominent issues are as follows:
1. The scale of individual enterprises is generally too small, while the sheer number of enterprises is excessive. Among Chinese manufacturers of low-voltage circuit breakers, only 2 to 4 large-scale enterprises possess both annual sales revenue and total assets exceeding 500 million RMB; the vast majority are small and medium-sized enterprises (SMEs). This situation results in a lack of economies of scale and diminished competitiveness. Furthermore, the number of Chinese low-voltage circuit breaker manufacturers has ballooned from a handful in the early days of the People's Republic to over 1,500 today. This excessive proliferation of enterprises leads to the over-fragmentation of economic resources and a lack of collective innovative momentum, ultimately resulting in suboptimal production efficiency, economic returns, and market competitiveness.
2. Regional industrial structures are converging, and redundant construction is severe. Due to the blind initiation of projects and indiscriminate expansion, China's low-voltage electrical appliance industry suffers from severe regional industrial convergence and low-level redundant construction. This has resulted in consequences such as product overcapacity, inefficient utilization of energy and raw materials, poor economic returns, as well as regional protectionism and cutthroat competition.
Advancements in vacuum circuit breaker technology are characterized by increased capacity, reduced overvoltage levels, enhanced intelligence, and miniaturization. These advancements, in turn, are the result of developments in vacuum technology and arc-extinguishing chamber technology, as well as the adoption of new manufacturing processes, novel materials, and advanced operating mechanisms. According to its inventors, this technology serves not only as a potential substitute for traditional motor technologies but also opens up vast new avenues for the development and application of DC motors. For instance, the development of high-capacity DC motors-intended to replace the AC synchronous generators and converter station equipment currently powering high-voltage DC transmission grids-could not only yield substantial savings in the construction costs of converter stations but also significantly reduce power conversion losses.
