According to the test of high speed circuit breaker used by city light rail,this paper proposes a kind of testing device of high speed circuit breaker based on a multifunction PCI high speed data acquisition and control card.

This article introduces the theory of the increment protection for high-speed DC circuit breakers in transformer substations and the protection for high-speed DC circuit breaker on trains, conducting a theoretic analysis and comparison between these two kinds of protective tripping.

The concept,basic principle,characteristic and basic composition of the permanent magnetism operating mechanism type in medium voltage quick-break circuit breaker are introduced.