AC Electromagnetic Interference Study between Railways and Nearby Power Lines under Steady-State Operation

AC electromagnetic interference (EMI) between railways and nearby power lines can compromise reliable operations of railway signal and protection systems and increase electrical shock hazards to the public and railway personnel. To maintain the continuity of railway operation and meet the railway safety standard, an AC EMI study is crucial. However, modeling AC EMI patterns in railways due to nearby power lines is complex, involving parameterization and characterization of AC EMI, and modeling the overall railway-power line system. Variations of design parameters along the right-of-way of rail tracks should also be considered. In this paper, the steps to conduct an AC EMI study for a rail system in the vicinity of a power line using the CDEGS software package is proposed. Sensitivity studies are conducted considering variations of several parameters, including the separation distance between railways and nearby power lines, length of the railway, ballast resistance, soil resistivity, power line loading, and voltage class of power lines. Based on results of these studies, a general guideline is developed in this paper to recommend the minimum separation distances between railways and power lines to mitigate AC EMI. An initial AC EMI assessment for a particular railway-power line system can be conducted using this guideline to determine if there are safety concerns and a detailed and costly engineering study is required.