The solid-state transfer switch is used to realize the operations of quickly putting into grid and quickly cutting out island for the new energy micro-grid in the comprehensive demonstration project of “Zhangjiakou-Yanqing” new power system. Because of its long-term on-state heat loss and internal device aging

the operation and maintenance are frequent

and the life cycle cost is high

which greatly affect the reliability of user power supply. Therefore

it is necessary to carry out the key technology research and engineering prototype development for the new high reliability fast mechanical transfer switch. We analyzed the typical application scenarios of fast switching under the new microgrid access

and put forward the engineering problems of the influence of switching time on the performance of short-circuit large current switching with high DC component

power electronic device electrothermal and sensitive induction motor of microgrid converter. Based on this

the technical requirements of the fast mechanical transfer switch were formulated

the overall structure of the coaxial vertical split-phase direct motion was designed and the working principle was described. At the same time

the fast switching stability was optimized. The key technologies of matching the breaking characteristics for the short circuit current and switching time

and the switching time influence for the thermal stress of microgrid converter and the speed and inrush current of induction motor were tackled. Based on the above research results

a 12 kV high-life fast mechanical transfer switch was developed

and the performance test was carried out. The test results show that the developed fast mechanical transfer switch meets the design requirements and has the application conditions for engineering upgrading.