Influence of AC Drainage Facility on Cathodic Protection Power Switch-Off Potential Test Results of Buried Pipeline

During the buried pipeline cathodic protection switch-off potential test, the capacitor discharge of solid-state decoupler could lead to inaccurate switch-off potential test results. From the aspects of solid-state decoupler structure, capacitor discharge characteristics and influencing factors of discharge circuit, the influence of solid-state decoupler on pipeline switch-off potential was analyzed, and the field test verified that AC drainage facilities would lead to the negative shift of the pipeline switch-off potential measurement value, indicating that the influence of solid-state decoupler on the switch-off potential of the pipeline was related to factors such as capacitance value, grounding electrode material, grounding resistance of grounding electrode and switch-on potential of the pipeline. The most effective way to eliminate interference effect of solid-state decoupler was to disconnect solid-state decoupler from the pipeline.