Measurement and Analysis of Stray Currents

Nowadays, the issue of stray currents is very actual, especially due to origin of electrochemical corrosion of storage devices. The biggest sources of stray currents are direct current traction systems such as railways and city lines using rails as a return conductor. In many cases, the return current does not flow back to traction converter substation by rails but uses other paths such as metallic devices stored under the ground (pipelines, metal-coat cables). This results in stray currents formation, which is the main cause of electrochemical corrosion. Electrochemical corrosion may cause serious damage of storage devices situated especially in proximity of direct current electrical traction systems. This paper deals with the issue of stray currents, describes the formation, spreading and the method of stray current measurement. The final part of this paper analyzes the results from real measurement of stray currents originating mostly from city tram lines. Measured data indicates a high activity of stray currents which can lead to damaging of metallic devices stored under the ground.