Design, monitoring and test of mechanical direct current automatic transfer switch

The automatic transfer switch (ATS) can solve problems of voltage drop and instantaneous power interruption, which is one of the most reliable and economical ways to improve the reliability and quality of the power supply. In view of the application requirements of important electricity place, this paper develops a mechanical direct current automatic transfer switch (DCATS) based on the LC resonant commutation, which is characterized by high reliability, fast switching, active and passive combined protection. Firstly, the system scheme and control principle of the mechanical DCATS are introduced. Then, the mechanical DCATS is designed, in which the mechanical switch uses the vacuum switch with the permanent magnet operating mechanism; the LC resonant branch uses the active LC oscillation triggered by the solid-state switch based on thyristor; the switching strategy adopts the series switching mode; and based on the performance of voltage, current and other electrical parameters, the parameter monitoring technology and scheme for monitoring the state of DCATS are proposed. Finally, a test platform is built to verify the feasibility of the technical scheme of the mechanical DCATS. Test results show that the mechanical DCATS can break more than10 kA within 8.3 ms and realize current transfer within 9.1 ms. It provides theoretical and technical basis for the product development and engineering application of the mechanical DCATS.