The fast mechanical switch（FMS）

as one of the core components of 500 kV hybrid high-voltage direct current（HVDC）circuit breaker

is requited to open within 2 ms and to withstand the transient breaking voltage up to800 kV. The quick opening and voltage withstand within 2 ms is the core technical requirement of the hybrid high voltage DC circuit breaker to the fast mechanical switch and the reliable barking ability of the buffering device of the fast mechanical switch is examined. Considering that the fast mechanical switch needs meeting the fast re-closing function design of HVDC circuit breaker and the traditional hydraulic oil buffer

polyester ammonia buffer and gas buffer have no way to meet the secondary buffering problem at the fast re-closing operation condition

such operation conditions as fast opening and closing as well as re-closing of the 500 kV hybrid HVDC circuit breaker are analyzed in this paper. A kind of electro-magnetic buffer method based on eddy current induction is proposed

the mathematical mechanism of electromagnetic buffer is studied

the finite element simulation model of electromagnetic buffering is set up and the influence of buffering capacitance

buffering current and buffering force on the electromagnetic buffering performance is analyzed. The 500 kV multi-break series fast mechanical switch is developed

the test verification is performed on the 500 kV hybrid HVDC circuit breaker commissioned in the Zhangbei ±500 kV DC grid and the correctness of simulation analysis is verified. The technology has practical engineering guiding significance for the electromagnetic buffering system and control design of fast mechanical switch.