| Types of stray current corrosion: Stray
current corrosion has been classified into the following types:
- Direct stray current corrosion, originating from direct current sources
such as dc rail transit systems, dc welding equipment and cathodic protection systems. In
general, direct stray current corrosion is considered the most severe form of these
problems.
The flow of direct stray current is not necessarily steady with time, in terms of
magnitude and current path(s). This has led to a further distinction between dynamic
stray currents (unsteady state) and static stray currents (steady state).
- Alternating stray current corrosion, originating from alternating
current sources such as overhead ac power lines.
- Telluric effects, a "natural" form of dynamic stray currents
induced by transient geomagnetic activity (disturbances in the earth's magnetic field).
References:
J.H. Fitzgerald III, "Stray Current Analysis", in Uhlig's Corrosion Handbook,
Second Edition, R.W. Revie Editor, Wiley, 2000.
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