It may surprise you to learn that in large process plants, as many as 30% of controllers are running in MANUAL. This means that they will do absolutely nothing to control the process. Hopefully, the operator will take notice, and get a handle on the process before things get out of control.
Leaving control loops in MANUAL can create environmental and safety hazards. So it is important to work toward getting the process back into its automated mode.
But here’s the problem: A loop in MANUAL is usually a SYMPTOM, not the root problem. The operator probably put the control loop in MANUAL for a reason…the controller tuning was bad, the valve was moving quickly enough, the sensor was unreliable, communications was lost, or something like that.
Go take a look at your DCS. See how many loops are running in MANUAL. Then talk to the operator. See if you can find out why the loops are in MANUAL. If they don’t know why, then try putting it back in AUTO, and see what happens.
Your goal should be that less than 10% of control loops are running in MANUAL. If you can get below 10%, you’ll be a world-class plant.