Interference of Stray Current from Subway Maintenance Base to High Pressure Natural Gas Pipeline and Protective Measures

Aiming at the situation that the pipe-to-soil potentials of high pressure natural gas pipeline nearby subway maintenance base fluctuated greatly, the main causes of positive and negative fluctuation of pipe-to-soil potentials were analyzed by synchronous detection about rail-to-soil potentials, electric currents in the rail of the base and pipe-to-soil potentials. When the main rail-to-soil potential shifted negatively, pipe-to-soil potentials moved towards positive direction. When the main rail-to-soil potential shifted positively and locomotive moved in or out of the base at the same time, pipe-to-soil potentials moved towards negative direction. When the main rail-to-soil potential shifted positively and no locomotive moved in or out of the base at the same time or base substations output current became large, pipe-to-soil potentials of pipeline fluctuated slightly.