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1.Introduction of Stray Current

In theory, negative current is collected to negative side of rectifier via the live rail (the third rail and so on) - EMU- rail. When the rail carries the actual current, voltage will drop on the rail and rail-to-ground resistance could not be completely insulated. Such insulation will make current leaked from the rail and then flow back to the rail via underground metal conduits or structure bars underground. This kind of current leaked from the rail is stray current, so-called lost current. The stray current cause the corrosion to many types of equipment near the running rail. It's important to suppress and to measure the stray current.

Diagram of Stray Current Monitoring System

2.Introduction of HISMAC® Stray Current Monitoring System (SCMS)

HISMAC® SCMS(Stray Current Monitoring System) is used for monitoring track potential of DC railway system. This system provides evaluation of the stray current conditions of the track, which facilitates early detection of insulation deficiencies and allows necessary measures to be taken to prevent potential damages caused by stray current corrosion.


  • Continuous monitoring of traction negative voltage during operation
  • Automatic identification of the position of insulation deficiency
  • Displaying, archiving and analyzing track potential via central evaluation device