Tue, 06 Dec 2016 14:59:00 -0500Just as you can't have too many friends, level measurement applications can't get enough ease of use, reliability and safety. Thanks to increasing process industry needs and user demand for them, these are the three unifying priorities that drove the design and development of Emerson Automation Solutions' new SIL 3-capable...
Tue, 06 Dec 2016 11:04:00 -0500ControlSoft Inc.’s PID Loop Tuning Pocket Guide has been expanded. This 12-page publication includes a short, easy-to-use guide for tuning PID loops, along with updated controller references for many of the more common controllers on the market today.
Mon, 05 Dec 2016 17:19:00 -0500Additions bring total number of participants to 33
Mon, 05 Dec 2016 14:14:00 -0500Control's monthly guide brings you invaluable industry information to stay up to date on the latest trends and developments.
Mon, 05 Dec 2016 13:34:40 -0500Able to bear the heavy loads of industrial applications, faster to assemble, and easier to populate electrical and electronic components.
Sun, 04 Dec 2016 20:49:00 -0500
In preparation for a new book, I was able to find information about an actual Aurora event. The event affected a non-utility facility (no generator involved) where it experienced multiple Aurora events over a multi-day span resulting in damage to motors.
Thu, 01 Dec 2016 20:30:00 -0500If the total loop deadtime becomes larger than the open loop time constant, you have a deadtime dominant loop. There is a lot of misunderstanding posed by this difficult challenge including a lot of prevalent myths. Here we look at how we get into this situation, what to expect and what to do. Deadtime is the ultimate limit to loop performance. A controller cannot correct for a disturbance until it starts to see a change in the process variable and can start to change the manipulated variable (e.g., flow). If the deadtime was zero, the controller gain could be set as large as you want and the peak and integrated errors made as small as you want provided there is no noise. The PID gain could theoretically approach infinity and lambda approach zero. Without deadtime, I would be out of job. Sources Fortunately, deadtime dominant loops where the deadtime is much larger than the open loop time constant, is usually relegated to a few loops for processes involving liquids and gases. Deadtime dominance typically occurs due to transportation delays (deadtime = volume/flow), cycle times of at-line analyzers (deadtime = 1.5 x cycle time, or improper setting of PID execution rates or wireless update rates (dead time = 0.5 execution or update rate time interval). Deadtime dominance due to transportation delay is more common in the mining industry and other processes that are primarily dealing with solids. Large transportation delays result from conveyors or feeders or extruders where the feed of solids are manipulated at the inlet and the quality or quantity is measured at the outlet (discharge) assuming the sensor lag is much less than the transportation delay (i.e., total loop deadtime). The use of a gravimetric feeder can eliminate the delay for feed flow control making a much more precise and responsive loop. A kiln has a temperature sensor lag that creates an open loop time constant that is usually larger than the transportation delay. However, the use of an optical sensor (e.g., pyrometer) for temperature control eliminates this lag possibly making the loop deadtime dominant. In vessels and pipes where there is no axial mixing, also known as back mixing due to an agitation or recirculation or sparging, there is no mixing up and down in the vessels and mixing forward and backwards in the pipe. We call this plug flow. There may be radial mixing, to make the concentration or temperature in a cross section of the vessel or pipe more uniform or to keep solids dispersed. Radial mixing does not reduce transportation delays whereas axial mixing eliminates plug flow decreasing transportation delays. Any remaining delay from axial mixing depends upon the degree of mixing. For vessels with good geometry and axial agitators, the delay is approximately the turnover time that is the volume divided by the summation of the agitator pumping rate, recirculation rate and feed rate. Deadtime dominance usually doesn’t occur in temperature loops except for inline systems, such as plug flow liquid or polymer reactors where there is negligible heat transfer lag in the equipment or sensor. Consequences For a deadtime dominant system, the peak error for a step load disturbance approaches the open loop error (error if loop is in manual). Better tuning and feedback control algorithms cannot do much to improve the peak error. There can be a significant improvement in the integrated error by better tuning and feedback algorithms for a load disturbance but the ultimate limit to the integrated error is the peak error multiplied by the deadtime. Solutions The best solution is to eliminate the deadtime that is the source of deadtime dominance by better process, equipment or automation system design. The next best solution is feedforward control given a reliable timely measurement of the disturbance. The feedforward measurement does not need to be extremely accurate. An er[...]
Thu, 01 Dec 2016 13:52:00 -0500Software packages, data management and storage methods, new communication protocols, programming tools, and cloud-computing services from the IT side.
Wed, 30 Nov 2016 14:48:00 -0500Big data can only help users if they understand what it is, how it can affect their controls and processes, and how they can use it to optimize operations.
Wed, 30 Nov 2016 14:07:27 -0500Aims to boost team productivity by enabling users to collaborate and share knowledge, view live production diagnostics, interact with machine alarms, and troubleshoot devices.
Wed, 30 Nov 2016 11:44:00 -0500Electricity, water, wastewater services in Arkansas city establish secure network and SCADA to optimize operations and assist economics
Tue, 29 Nov 2016 18:20:00 -0500Powerful connectivity, integration and visualization lead to better decisions in real time.
Tue, 29 Nov 2016 18:06:00 -0500Tank blanketing with nitrogen prevents contamination, leaks, and explosions. Download FCI's Tank Blanketing White Paper to learn how FCI’s ST100 Air/Gas Flow Meter provides precise flow measurement to reduce the cost of inert gases.
Tue, 29 Nov 2016 16:14:00 -0500Sierra Nevada's David Lewis explores how the company set out to achieve proactive identification of failing RTDs and improve its data visualization tools.
Tue, 29 Nov 2016 15:55:00 -0500Partnership aims to bridge gap between existing industrial assets and infrastructure, and the digital world of mobile, cloud and IT.
Mon, 28 Nov 2016 18:04:00 -0500'To the degree networks and standards can provide easy, consistent and seamless access to device-resident controls, the vision of truly distributed control may finally dawn upon us.'
Mon, 28 Nov 2016 14:33:00 -0500This report details how rising global demand, climate change concerns and the drive to U.S. energy independence have created a strong environment for innovation in process control.
Mon, 28 Nov 2016 14:21:00 -0500
The presentation reviewed the threat to commercial/industrial power distribution networks and the various network protocols susceptibility to cyber attacks.
Wed, 23 Nov 2016 12:16:00 -0500What to do when the process overshoots the mark.
Tue, 22 Nov 2016 12:49:00 -0500With today’s network technology, even Ethernet and wireless are almost always fast enough.