Control system modernization of older SCR electrochemical rectifiers

This paper describes the application of modern microprocessor-based control design to upgrade the control system and protection of a system of early SCR rectifiers used in an industrial electrochemical plant. The paper discusses the problems of the existing power system, and the benefits desired from the project, as well as the issues leading to the decision to proceed with the project. Design considerations are discussed along with the elements to be retained from the original control system. The steps in planning the conversion of each unit in the system are shown, including module preparation and testing, removal and rewiring and test sequences. Connection of the system into an operators central industrial PC for unit monitoring is described. Finally, other possible options are shown, with a discussion of their potential benefits.