The world's oldest circuit breaker was produced in 1885. It is a combination of a knife head and an overcurrent release. In 1905, an air circuit breaker with a free tripping device was born. Since 1930, with the advancement of science and technology, the discovery of the arc principle and the invention of various arc extinguishing devices have gradually formed the current mechanism. At the end of the 1950s, due to the rise of electronic components, electronic release devices were again produced. Today, due to the popularity of SCMs, intelligent circuit breakers have been introduced.