Stray current protection development

In general, steel in concrete operates in the interval of potential and pH outside the critical ranges for hydrogen evolution. Under particular conditions, however, the situation may be different. Situations that make it jxtssible for hydrogen to develop are localized corrosion on the reinforcement that lead to oxygen depletion (and thus depresses the potential), acidity production at the anodic zones, and external cathodic polarization applied to the steel (due to, for example, excessive cathodic protection or stray currents). 

A protective rectifier between pipeline and rails that was installed by Kuhn in 1928 was the forerunner of modem forced drainage. This form of controlled stray current drainage was developed further, particularly in France, in combination with stray current relays. The first such polarized drainage was installed at Bad Diirheim in 1975 and had an appearance similar to the cathodic protection rectifier in Bogenheim, shown in Fig. 1-14. Today mainly controlled potential rectifiers are used for stray current drainage. The first of these, in Wuppertal-Cronenberg, conducted peak currents of more than 200 A between 1961 and 1970. 

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