AC interference between co-located pipelines and high voltage AC powerlines can result in safety hazards to operating personnel and the public under powerline steady-state and fault conditions.
Under steady-state conditions, AC voltages are induced on the pipeline via electromagnetic coupling. Under fault conditions, high AC voltages can be present via electromagnetic coupling and AC currents discharging into the earth from the powerline structures, i.e., conductive coupling. These high voltages can result in serious injury or death to any person in contact with any above-ground metallic appurtenance that is electrically continuous with the pipe.
The type and magnitude of AC interference hazards are dependent on many factors including the co-location configuration, the electrical resistivity of the soil, the AC currents on the powerline, and the powerline and pipeline characteristics. Consequently, AC mitigation strategies must be put in place to ensure the safety of all persons and must be tailored according to the various conditions.
This paper discusses the factors that should be considered when designing AC mitigation systems for pipeline facilities. Such factors include facility layout, isolation points, fencing, and ground conditions. The paper also discusses the different mitigation strategies that can be implemented including gradient control grids, ensuring electrical continuity, and grounding.
