Railways require safe, reliable power systems to support signals, track heaters, switching points, and communication infrastructure for both rolling stock and rail cars. Trackside equipment must also be protected from failure, and with thousands of miles of track to maintain, rail operators demand maximum visibility to assess information regarding the health and condition of its infrastructure in real time. US rail transit systems are subject to harsh operating conditions and incidents of theft, accidental damage, and degradation. Finding and locating faults is challenging, often requiring rail personnel to spend thousands of hours along the track inspecting and locating failing cable. Because of this, rail personnel are constantly seeking more efficient ways to locate faults and in turn, save valuable time and money.
The benefit of effective fault finding translates into fewer train delays and improved customer service with reduced associated costs for rail operators. More than 50% of rail signaling power supply issues result from ground-faults where damage or deterioration of a cable or its insulating covering will eventually lead to failure, impacting the safety and efficiency of rail operations. Since rail signaling systems are typically ungrounded, a faulted circuit could change the state of a signal or trigger the shutdown of the train. On ungrounded systems, the first ground fault can typically go undetected for days or months, or worse, until a devastating second ground fault occurs while the first fault remains. Critical faults that emerge at lower intervention/insulation limits are even more difficult to track and pinpoint, and therefore present a greater challenge.