Section insulator is one of the catenary section device. In electrified railway, set in the line of goods and cargo handling operation station line, locomotive servicing line, the same station between the yard and double line segments between, downward on the station,under normal circumstances, the CRH train(locomotive) pantograph slide through.when somewhere of the catenary break down or due to the need of maintenance of power failure,can open the disconnector on the section insulator to power failure this part and the other part can still normal power supply,thereby improve the reliability and flexibility of the catenary operation.