A technique for predicting stray current effects based on injection and selective measurement

The author discusses one specific aspect of the interference between systems, that is, a technique for measuring the effect of specific sources. This technique is intended to facilitate the detailed investigation of the influence of an interfering source on other systems in the presence of other interference. It also offers opportunities to carry out measurements over an extended period of time, of what would otherwise have been transitory phenomena. The basic principal of the technique is to generate a current at some convenient frequency, in the supplying circuit, so enabling the identification and measurement of that current in all the paths in which it flows. This current takes the same paths as a normal load current at the point of injection, but is distinguishable from other load currents. The author describes the technique and its application. An example of its use for establishing earth paths is discussed