Abstract :
The problem involved in producing direct current for electrochemical processes is outlined, and the difficulties are pointedout. Of the methods of power supply using steam turbines that are available, it is shown that: (a) Direct-connected d-c. turbogenerators are available only in relatively small units, and cannot be designed as conservatively from the commutation standpoint as is desirable. (d) Unipolar generators driven by turbines have proven unsatisfactory on account of current collection difficulties. (c) The standard medium-speed d-c. generator connected to a high-speed turbine through gearing affords a satisfactory unit. (d) The combined a-c. turbogenerator and converter unit probably affords the best all-around method. It is economical, reliable and flexible. Its particular fields of application are where large units and long transmissions are required. In waterpower plants, direct-connected d-c. generators and a-c. generators with converters are available. The combined a-c.-d-c. equipment is usually the most reliable and economical. With reciprocating engine units, there is no reason for considering other methods than the direct-connected slow-speed generator.
