Control modernization of SCR rectifiers with continuous device current monitoring

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. The paper discusses the problems of the existing 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. Integration of the new control system with a device current monitoring system is discussed. Connection of the system into an operator´s central industrial PC for unit monitoring is described. Finally, operating data is shown, with lessons learned about device current balance. Conclusions are given with applicability to all large rectifier systems