Prof. Dr. Zhiyuan Liu is one of the major contributors in the research field in transmission voltage level vacuum circuit breaker in China. His team developed the first 126kV/2500A/40kA single-break vacuum circuit breaker in China, which passed type test in 2013. The contribution is toward to reduce SF6 gas usage in high voltage switchgear. SF6 gas is a strong global warming effect gas pointed by Kyoto protocol. In the field of transmission voltage level vacuum circuit breaker, he held 128 Chinese patents and 2 US patents. He published 520 technical papers, mainly in the field of vacuum circuit breaker, including vacuum arc, vacuum insulation, operating mechanism ect.