A new solution to inductive interference borrowed from electric railroad propulsion signal methodology

The mitigation of a severe case of inductive interference by using railroad signaling equipment designed for electrified railroad territory is detailed. In 1983, Consolidated Rail Corporation (Conrail) agreed to permit Philadelphia Electric Company (PECo) to build and operate a 230-kV transmission line on a seven-mile section of main line in suburban Philadelphia. It soon became apparent that only 600 MVA was sufficient to interrupt service and damage Conrail´s signal facilities. A low-resistance path to ground for the 60-Hz interference currents was therefore provided. Since existing signal systems operating in electric propulsion territory provide this separate path, such equipment was used to resolve the induction problem in the subject nonelectrified railroad applications. Field measurements were taken with a transmission line load of 828 MVA and were used to predict the performance of the signal system at the maximum projected transmission line loading of 1418 MVA steady-state. Based on the calculated results, it was concluded that the signal system will operate satisfactorily at maximum load