Dynamic Stray Current Interference Mitigation Commissioning Testing for a 90 Inch (2.28 m) Water Main

A 90 inch water main runs parallel and is in close proximity to a Chicago Transit Authority (CTA) DC electric railroad.  Prior testing indicated the presence of DC stray current interference on the 90 inch pipeline due to the effects emanating from the DC electric railroad.  This ultimately led to more advanced testing and design of a bond using a reverse current drainage switch (RCDS) to mitigate the interference caused by the DC electric railroad.

A reverse current drainage switch is a device that allows current to flow through a bond when the potential of the pipeline is more positive than the potential on the railroad.  Once the potential of the pipeline becomes more negative than the potential of the railroad the reverse current drainage switch opens to hinder the current flow.

This paper discusses the final commissioning and testing performed on the reverse current drainage switch installed between the pipeline and the DC electric railroad and compares these results with the previous design.

Keywords: DC interference, DC train system interference, water main, stray current corrosion