A web-based control loop assessment, condition-based monitoring, and alarm management system saves CEZinc $900,000 per year
In most plants, control maintenance falls into two categories. The physical equipment--valves, instruments, actuators, etc.--is maintained on a schedule. Annual preventive maintenance is very common for these components.
Controller tuning parameters, on the other hand, are rarely the subject of scheduled maintenance. Most controllers are tuned only when the tuning is so bad that the operator notices a problem and tells a maintenance technician, either directly or through a maintenance request system. The reason for this situation may be the fact that tuning parameters are not considered to be assets in the maintenance management system. Since they are not assets, there is no way to schedule maintenance for them.
Controller tunings need to be maintained. In the absence of anything better, scheduled maintenance of controller tuning would ensure that the tuning parameters would be correct at least once a year. But scheduled tuning is not the most appropriate method of controller maintenance, because of the reasons that cause degraded performance. Valves and transmitters fail usually because of an accumulation of wear. Controller tuning does not wear out; it becomes inappropriate. The only appropriate method to schedule the maintenance of controller tuning is condition-based maintenance.