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Despite today's technology, discovery remains an arduous—and rewarding—process

Thu, 19 Oct 2017 14:28:00 -0400

With the focus we have today on spreading information around (and that’s extremely valuable), we tend to overlook the importance of developing it in the first place.



Common Mistakes not Commonly Understood - Part 1

Wed, 18 Oct 2017 20:40:00 -0400

There are many mistakes but some are repeated over and over again even though the automation engineer is attentive and experienced and has the best intentions. Part of the problem is overload in terms of tasks and the time crunch. It is highly unlikely engineers today read even a smattering of the thousands of pages in books, handbooks, white papers and articles. The knowledge to prevent the following mistakes may be buried in this literature but I am not so sure of even this. In any case, one probably could not find it. Here is my effort to get straight to the point of realizing and fixing mistakes. (1) Reset time set too large for deadtime dominant processes. Most tuning algorithms don’t recognize what Shinskey found is that the reset time could be decreased by a factor of 8 or more from 3 to 4 times the dead time to 0.4 to 0.5 times the dead time for the same controller gain setting for severely dead time dominant processes. Lambda tuning can accomplish a dramatic reduction in reset time since the reset time is the time constant that for dead time dominant processes is by definition less than the dead time. The controller gain is also proportionally reduced providing stability despite a much smaller reset time, which is generally good since these processes are more likely to have noise and a jagged not so smooth response due to the lack of a significant time constant. The criticism that the controller reset time and gain becomes too small leading to integral-only type of control for severely dead time dominant processes is avoided by simply putting a limit of ¼ the dead time on the reset time that is then used in the equation for the controller gain as discussed in the June 2017 Control Talk Column “Opening minds about controllers, part 1”. This column is also a good resource for understanding the next common mistake where the reset time is set too small. (2) Reset time set too small for lag dominant (near-integrating) processes, integrating and runaway processes. These processes lack self-regulation in the process and depend more upon the gain action in the PID to provide the negative feedback missing in the process. Since engineers are not comfortable with controller gains greater than 5 and operators object to sudden movements of PID output, the controller gain is often an order of magnitude or more too small. Since the product of the reset time and gain must be greater than twice the inverse of the integrating process gain to prevent the start of slow oscillations, the reset time is an order of magnitude or more too small. Since we are taught in control theory classes how too high a PID gain causes oscillations, the PID gain is typically decreased making the problem worse. For more on this pervasive problem and the fix, see the 9/14/2017 Control Talk Blog “Surprising Gains from PID Gain” which leads us to the next common mistake. (3) PID gain set too small for valves with poor positioner sensitivity and excessive dead band from backlash and variable frequency drives with a large dead band setting. Not only is the PID gain too small per last mistake but is also too small to deal with valve problems as seen in my ISA 2017 Process Control and Safety Symposium slides ISA-PCS-2017-Presentation-Solutions-to-Stop-Most-Oscillations.pdf that details a lot of cases where a counterintuitive increase in PID gain reduces or stops oscillations. (4) Split ranged valves used to increase valve rangeability. The transition from the large to small valve is not smooth since the friction and consequently stiction is greatest near shutoff as plugs rub seats and balls or disks rub seals. Since the stiction in percent stroke translates to a larger abrupt change in flow and amplitude in the limit cycle, small smooth changes in flow are not possible especially near shutoff but also whenever the large valve is open.  The better solution is a large and small  valve stroked in parallel either where a Valve Position Controller manipulates the large valve with directional move suppression to keep the s[...]



Hacking the grid may not be as difficult as the October 13, 2017 Wired article suggests

Wed, 18 Oct 2017 15:21:00 -0400

Aurora, forced oscillations, and other types of incidents that can manipulate physics may not be a difficult to cause as previously believed and may not be detectable from network anomaly detection.

 




Patience has rewards: Top 50 automation companies of 2016

Wed, 18 Oct 2017 10:57:00 -0400

The Top 50 worldwide and North American process control and automation suppliers are making slow, consistent gains with help from the Industrial Internet of Things (IIoT).



Infrared thermography: Part of an effective preventive maintenance strategy

Tue, 17 Oct 2017 23:55:00 -0400

Learn how the maintenance manager at a saw mill found that adding thermography to their maintenance program not only improved their reliability and efficiency – it also saved more than the price of the camera in a single timely repair.



Watlow ASPYRE power controllers

Tue, 17 Oct 2017 23:39:20 -0400

Firing modes include zero cross, burst firing, single cycle, delayed triggering and phase angle. Combined with diagnostics and a wide range of communications options, ASPYRE aims to enable equipment and factory automation.



NovaTech details digital, DCS future

Sun, 15 Oct 2017 12:16:00 -0400

Several dozen users, engineers, managers and IT professionals exchanged experiences and best practices on process and plant performance, quality, safety, loop tuning and cybersecurity



The expert inside, part 2—flow

Sun, 15 Oct 2017 11:43:00 -0400

Microprocessors and Ethernet ports have brought smarts to field instruments such as flow detectors, meters and switches, but now they're also capturing more useful data in simpler-to-use, better-networked devices.



Industry signals and indicators - October 2017

Fri, 13 Oct 2017 12:01:00 -0400

Siemens taps PAS Global for cybersecurity efforts; Endress+Hauser acquires IMKO Micromodultechnik GmbH; ABB opens AbilityCollaborativeOperationsCenter; among others



Pressurization affects hopper weight

Fri, 13 Oct 2017 11:33:00 -0400

Why does our hopper weight appear to drop during pressurization?



Waze saves the bacon

Fri, 13 Oct 2017 11:00:00 -0400

Mobile means you can get the information you need, wherever you are, in real time.



IIoT and asset management

Wed, 11 Oct 2017 16:13:00 -0400

There will be no end to the rewards of connecting everything



Getting away from batch opens opportunities for quality and throughput

Mon, 09 Oct 2017 22:20:00 -0400

It works fine for beer or shampoo, but when you're mixing solids like metal powders, it's strictly impossible for every bit of the batch to experience the same process.



Resource guide: enterprise integration gets down to business

Mon, 09 Oct 2017 21:21:00 -0400

Our latest slate of articles, videos, white papers and other resources comes from ISA, Corso Systems, OPC Foundation, and others.



Panel session on using cyber to manipulate physics to cause kinetic damage

Sat, 07 Oct 2017 14:37:00 -0400

October 25th at the 2017 ICS Cyber Security Conference in Atlanta, Neil Holloran, Ken Loparo from Case Western, and myself will host a panel session on using cyber means to manipulate physics. 




Live from 2017 NovaTech Automation Summit

Fri, 06 Oct 2017 14:56:00 -0400

The editors of Control were on site at the 2017 NovaTech Automation Summit in Baltimore. Here, we offer coverage of some of the presentations addressing process control's most interesting challenges and pressing problems.



Does the term OT contribute to the lack of security in Level 0,1 devices

Fri, 06 Oct 2017 10:47:00 -0400

The term OT does not address the Level 0,1 devices and may be contributing to the lack of security considerations in these devices. 




Tuning loops, saving money

Thu, 05 Oct 2017 12:47:00 -0400

Bob Rice, vice president of engineering at Control Station Inc., shows how his company and NovaTech help users overcome historical trial-and-error loop tuning by using best practices for loop tuning and their six-step D3LO tuning recipe.



Chemical Safety Board keeps on striving

Thu, 05 Oct 2017 12:42:00 -0400

U.S. Chemical Safety Board member Manny Ehrlich described the CSB's goals and strategies in his keynote address at the opening of NovaTech Automation Summit on Sept. 18.



Five win best-in-conference awards at Emerson Global Users Exchange

Thu, 05 Oct 2017 12:38:00 -0400

Best-in-track presentations selected from among the more than 400 given.