Every rectifier plant must provide continuous, reliable, adequate and safe DC power. The aging installed base of high-power rectifier systems is beginning to require extended downtimes for maintenance and repairs, as well as unscheduled outages. Because rectifiers provide DC current to a host of critical process applications, their inability to operate when needed will result in financial losses for the owners. Over the years, the electrical performance of a plant deteriorates if left unmanaged, but the health of industrial processes can be re-established or improved relatively easily with a lifecycle asset management plan. A majority of plants, as a whole, suffer reduced productivity due to insufficient power, unscheduled shut downs, unforeseen accidents, etc. However, the implementation of conventional maintenance procedures is not practical to improve the availability, safety, productivity and efficiency of a plant beyond a certain level. Failures in old control components generally cause longer downtimes since these parts are either unavailable, obsolete or need to be repaired. From a systems level, most control systems were designed to operate manually, local to the rectifier unit, (i.e., remote control was often not provided). Operating a group of rectifiers from different locations can introduce a source of error and inefficiency-a master control unit should manage these systems with expanded remote control capability. Additionally, analog systems exhibit inherent limitations due to temperature drift. This paper presents the results of recent upgrades performed on analog control systems replaced with a digital controller, leading to increased plant availability and delivering significant production increases.
