Heavy-duty rectifiers and their application to traction substations

As a result of the special problems associated with the supply of direct current to traction systems, as distinct from lighting and power systems, automatic substation technique has advanced in two widely diverging directions. Whereas modern substation practice in America is characterized by practice favours the adoption of mercury-arc rectifiers. The paper reviews the present state of development of the ironclad rectifier and its application to traction supply as reflected in the more recent converting installations on the Continent. The requirements peculiar to traction operation are outlined, and the extent to which they are fulfilled by the different classes of converting plant is briefly discussed. The leading operational features of the mercury-arc rectifier are indicated and a general description of the modern heavy-duty rectifier is given. Factors influencing thelay-out and equipment of rectifier installations are investigated and a typical rectifier substation designed for fully automatic control is described. The paper concludes with a comparison between Great Britain, America and Germany as regards the extent to which mercury-arc rectifiers are employed for the supply of direct current. A review of the more important literature on the theory of the mercury-arc rectifier, together with a brief general bibliography, is given in an appendix to the paper