An overview of the magnetic field coupling mechanisms from overhead electric power lines collocated with buried pipelines is presented. Such coupling results in ac voltages and currents being induced unto the pipeline. Inductive coupling during normal (steady state) operation of the electric power system and during fault periods is reviewed. Conductive coupling to the pipeline which additionally occurs during fault periods is also discussed. Pipeline induced voltage levels are dependent upon the soil resistivity along the right-of-way. For complex rights-of-way (ROW), because of computational diffculty, computer programs are generally utilized to model the ROW and obtain numerical solutions. Available computer programs are based either upon a single or two layer earth resistivity model. The advantages and consequences of using one or the other models for the prediction of induced voltage levels are discussed.
Keywords: ac induction, induced ac voltages, soil resistivity
measurements, two layer soil resistivity modeling