In the field of power industry, it is the core equipment that ensures the safe and stable operation of the power grid, covering the entire process of power generation, transmission, distribution and consumption. Continuously evolving towards higher voltage, faster response, and greater intelligence in its industry is a key equipment for building a new type of power system. Its core functions include fault isolation, equipment protection, system control, etc., which need to cope with high voltage, high current, and complex fault conditions. With the increasing proportion of renewable energy and the digital development of the power grid, its technological innovation will focus more on cutting-edge fields such as flexible disconnection and multi terminal protection.