Category: Measurement Repeatability Noise PID Tuning Process Dead Time Process Gain Process Repeatability Process Time Constant Tips Valves
Submitted by Greg McMillan on Mon, 01/19/2015 - 16:18
Each process test will typically give a different result in the process dynamics identified and consequential tuning settings calculated. Here we look at the sources of this lack of repeatability, the implications, and what can be done to improve tuning tests.
Category: Bioreactor Control Dead Time PID Tuning Process Dynamics Process Gain Time Constant Tips Valve Position Control Variable Speed Pumps
Submitted by Greg McMillan on Fri, 12/06/2013 - 16:39
Here we use the broader definition of linearity to mean constant dynamics. A linear control loop has a constant total loop dead time, constant primary and secondary time constants, and a constant open loop gain. This perspective reviews the sources of dynamics and causes of nonlinearity.
Category: Process Dead Time Process Dynamics Process Gain Process Noise Process Time Constant Tips Valves Variable Frequency Drives Variable Speed Pumps
Submitted by Greg McMillan on Sun, 07/28/2013 - 09:54
I have dug deep into my memory to add 21 more items to the list of process, mechanical, and piping design mistakes that have made our job as automation engineers more challenging and in some cases impossible. We learn the most by our mistakes.
Category: Process Dead Time Process Dynamics Process Gain Process Noise Process Time Constant Tips Valve Valve Position Control
Submitted by Greg McMillan on Fri, 07/19/2013 - 15:06
With a little help from my friends I have come up with a list of process, mechanical, and piping design mistakes that have made our job as automation engineers more challenging and in some cases impossible. We learn the most by our mistakes.
Submitted by Greg McMillan on Thu, 07/11/2013 - 06:09
Most process engineers were not taught how process and equipment design affect loop dynamics and performance. Many of the more demanding control applications are the result poor process dynamics. Automation engineers can help bridge the gap and be able to intelligently discuss how plant design is affecting plant performance.
Submitted by Greg McMillan on Fri, 06/14/2013 - 16:46
A significant part of the challenge in understanding process control is the proper use of terms to describe the dynamics in a control loop. Communication can be greatly improved by focusing on three key terms and adding a few words to more aptly describe the source of the term.
Category: Integrating Process Near-integrating Process Process Dead Time Process Dynamics Process Gain Process Time Constant Runaway
Submitted by Greg McMillan on Thu, 08/02/2012 - 21:29
Do you lie awake at night wondering what the source of process dynamics is? Do you wonder why temperature and composition controllers tend to oscillate at low production rates and low levels? Are you perplexed why some controllers need a lambda factor of 2 and others need a lambda factor...