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2018 Control Process Automation Hall of Fame - Part 2: Herman Storey

Fri, 20 Apr 2018 14:49:00 -0400

Two new inductees join the Hall of Fame

In memoriam: Stan Weiner

Thu, 19 Apr 2018 13:50:00 -0400

Our greatest mentor guided us to the best in instrumentation and humor

Product roundup: fierce flow measurement, control

Thu, 19 Apr 2018 08:55:00 -0400

The latest flow measurement, control and support solutions aren't shy about serving in difficult settings

Sometimes operators sense changes missed by managers and engineers

Wed, 18 Apr 2018 09:50:00 -0400

Engaging the operations team can help troubleshooting

High-pressure mass spectometers offer robust, real-time, in-situ analysis.

Tue, 17 Apr 2018 09:52:00 -0400

Atonarp recently introduced a molecular sensor (quadrupole mass spec) solution

Control's 10 most-read articles from March 2018

Mon, 16 Apr 2018 16:48:00 -0400

From tips to avoiding PID tuning mistakes to potential system hacking, these were the Top 10 most-read articles on during the month of March 2018.

Video: Using magmeters in zero upstream, zero downstream applications

Mon, 16 Apr 2018 09:33:00 -0400

Siemens explains how magmeters work

Resource guide: Fieldbus, Ethernet networks explained

Mon, 16 Apr 2018 09:02:00 -0400

Control's monthly guide brings you invaluable industry information to stay up to date on the latest trends and developments.

Bedrock Automation releases OSA Remote

Mon, 16 Apr 2018 08:00:00 -0400

Compact controller unifies PLC, RTU and edge control, intrinsic cybersecurity, and universal I/O

Still little understanding of cyber security of process sensors and this is more important than Stuxnet

Fri, 13 Apr 2018 10:11:00 -0400

The focus of the ICSJWG presentations were on network considerations. Addressing cyber threats to the process sensors before they become Ethernet packets was not considered other than my presentation. Yet, this is a shortcut to compromising any safety system.

2018 Control Process Automation Hall of Fame - Part 1: Thomas McAvoy

Fri, 13 Apr 2018 09:05:00 -0400

Two new inductees join the Hall of Fame

Reader feedback: April 2018

Fri, 13 Apr 2018 08:15:00 -0400

Readers respond to February's Control Talk column and PID controller basics article

Factoring life cycle variables helps make intelligent motor-drive purchases

Thu, 12 Apr 2018 11:14:00 -0400

The largest potential for electric motor energy savings lies in system- and process-level optimization

When is an Automation System too Slow and too Fast?

Wed, 11 Apr 2018 13:22:00 -0400

The usual concern is whether an automation system is too slow. There are some applications where an automation system is disruptive by being too fast. Here we look at what determines whether a system should be faster or slower and what are the limiting factors and thus the solution to meeting a speed of response objective. In the process, we will find there are a lot of misconceptions. The good news is that most of corrections needed are within the realm of the automation engineer’s responsibility. The more general case with possible safety and process performance consequences is when the final control element (e.g., control valve or variable frequency drive), transportation delay, sensor lag(s), transmitter damping, signal filtering, wireless update rate and PID execution rate is too slow. The question is what are the criteria and priorities in terms of increasing the speed of response. The key to understanding the impact of slowness is to realize that the minimum peak error and integrated absolute error are proportional to the deadtime and deadtime squared, respectively. The exception is deadtime dominant loops that basically have a peak error equal to the open loop error (error if the PID is in manual) and thus an integrated error that is proportional to deadtime. It is important to realize that this deadtime is not just the process deadtime but a total loop deadtime that is the summation of all the pure delays and the equivalent deadtime from lags in control loop whether in the process, valve, measurement or controller. These minimum errors are only achieved by aggressive tuning seen in the literature but not used in practice because of the inevitable changes and unknowns concerning gains, deadtime, and lags. There is always a tradeoff between minimization of errors and robustness. Less aggressive and more robust tuning while necessary results in a greater impact of deadtime in that the gain margin (ratio of ultimate gain to PID gain) and the phase margin (degrees that a process time constant can decrease) is achieved by setting the tuning to be a greater factor of deadtime. For example, to achieve a gain margin of 6 and a phase margin of 76 degrees, lambda is set as 3 times the deadtime. The actual errors get larger as the tuning becomes less aggressive. The actual peak error is inversely proportional to the PID gain. The actual integrated error is proportional to the ratio of the integral time (reset time) to PID gain. Consider the use of lambda integrating process tuning rules for a near integrating process where lambda is an arrest time. If you triple the deadtime used in setting the PID gain and reset to maintain a gain margin of about six and a phase margin of 76 degrees, you decrease the PID gain by about a factor of two times the new deadtime and increase the reset time by about a factor of two times the new deadtime increasing the actual integrated error by a factor of thirty six when the new deadtime is 3 times the original deadtime. Consequently, how fast automation system components need to be depends on how much they increase the total loop deadtime. The components to make the loop faster is first chosen based on ease such as decreasing PID and wireless execution rate, signal filtering and transmitter damping assuming these are more than ten percent of  total loop deadtime.  Next you need to decrease the largest source of deadtime that may take more time and money such as a better thermowell or electrode design, location and installation or a more precise and faster valve. The deadtime from PID and wireless update rates is about ½ the time between updates. The deadtimes from transmitter damping or sensor lags increase logarithmically from about 0[...]

The vicissitudes of fate may raise you up or take you out

Wed, 11 Apr 2018 13:01:00 -0400

Little in our past can prepare us for life's occasional surprises

How to design functional enclosures to protect electronic devices

Tue, 10 Apr 2018 00:00:00 -0400

It's easy to make small and costly mistakes when specifying and applying enclosures

TPG to buy Wind River from Intel

Tue, 10 Apr 2018 00:00:00 -0400

Wind River President Jim Douglas and his existing executive management team will lead the newly independent Wind River after the transaction closes

Hacking Level 0,1 devices can be more significant than Stuxnet

Mon, 09 Apr 2018 18:34:00 -0400

The lack of cyber security and authentication of Level 0,1 devices precludes adequate cyber security and safety. The threat is independent of vendor, industry, region, or application and therefore can be even more significant than Stuxnet.

Vortex flowmeter calibration & rangeability

Mon, 09 Apr 2018 14:57:00 -0400

How can we determine the best size to balance accuracy against pressure drop?

New ISA99 standard integrates security-by-design

Mon, 09 Apr 2018 14:04:00 -0400

New standard specifies process requirements for the secure development of products used in an IACS