For meeting the requirements of frequent switching of load current of flexible DC power distribution system to the operation life of switchgear and solving the difficulty of high cost and large volume due to the direct use of DC circuit breaker

a kind of DC load switch scheme based on couple negative voltage principle is studied in this paper. Firstly

its topology and working principle are introduced. Then

the fast mechanical switch in the main branch based on double-acting structure and electromagnetic repulsion mechanism

the converter unit based on the coupled negative voltage device and the power electronic valve unit using the anti-series topology

are designed respectively. Finally

according to the engineering requirements of a converter station in Suzhou

a 10 kV coupled negative voltage DC load switch prototype is developed and verified by tests. The result shows that the developed 10 kV DC load switch can frequently interrupt the rated current and the maximum breaking current within 3 ms

the volume at present is the smallest with the same parameters in China

and it has the advantages of low loss

high mechanical life and reliability. It fully satisfies the engineering requirements and

at the same time

provides a reference for the development of subsequent DC load switch products.