Development of Stray Current Protection

The first underground railway in the world was opened on January 10,1863 in the City of London, operating with steam locomotives. The first line with electric traction and a three-rail system was built in 1890. The four-rail system, still in use today and consisting of two insulated conductor rails and two running rails, was introduced in 1903 in the course of electrification of the old steam tracks. The Metropolitan Company, responsible for a part of the track, used ac, while the District Railway preferred dc as a consequence of the connection with the American railways. This dispute came before a British arbitration tribunal in 1900. The problem of corrosion of public supply lines by the returning current fi om electric train 

Deliberate stray current drainage was installed at a subrectifier in Germany as early as 1895 during the electrification of the Aachen tramway. The effective protection extended over a relatively small field since the comparatively large resistance of the pipe Joints did not permit a greater extension of protection. 

The Berlin City electrical engineer M. Kallmann reported in 1899 on a system for controlling stray currents of electric railways [64]. As early as 1894, the Board of Trade in London issued a safety regulation for the British electric railways which specified a potential differential of not more than 1.5 V where the pipeline was positive to the rails, but 4.5 V with the rails positive. Extensive research was undertaken on reducing the risk of stray current in the soil by metallic connections from pipes to rails. However, as one writer noted, a procedure on these lines should definitely be discouraged as it carries the seed of its own destruction [64], 

The Journalflir Gasbeleuchtung mentions electrolytic corrosion damage caused by direct current cables in Berlin in 1892, and a few years later damage by tramway currents was reported in 14 German towns. As early as 1894 the electrolytic processes of stray current corrosion were explained in detail in this journal by G.Rasch [65]. 

In 1910, a joint commission of the associations of German electrotechnicians and gas and waterworks engineers issued regulations for the protection of gas and 

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