This paper presents a simple velocity control algorithm with output modification that has equivalent PI controller dynamic performance. The controller features a single control setting. The controller can be easily configured in most distributed control systems, DCS and programmable logic controllers, PLC. This paper describes the controller structure and behavior as well as a control discussion on how to calculate the gain setting to determine the control period. To test the controller on real processes, the algorithm was applied to a level and temperature control loops in a laboratory, pilot plant setting.
A control algorithm presented by W. Steven Woodward describes a velocity temperature controller  that modifies the output based on the pervious output value when the process variable, PV, crosses the set point, SP. This modification is the algebraic mean of the current calculated output and the output value at the previous zero error crossing. The term coined for this algorithm is "Take-Back-Half", TBH. This algorithm has some acceptance as an embedded application controller. In this paper we will demonstrate how this controller has applicability to the process control community. In section 2, we will describe how this simple controller functions and how to program the algorithm. Section 3 discusses the controller system design and how to determine the gain setting and closed loop period. In section 4 we will present the results of the pilot scale controllers performance. In section 5 we will set forth the conclusions.02/23/2010
Selecting the right MCC equipment leads to improved plant safety, helping protect people and capital investments.
Measures to increase equipment and personnel safety in manufacturing are reflected in new approaches and technologies designed to help minimize the risk of workplace dangers. One rapidly growing area of focus is reducing the potentially serious hazards associated with arc-flash events. This white paper examines the causes of arc flash, discusses the standards guiding arc-flash safety and details the role arc-resistant motor control centers (MCCs) play in helping contain arc energy. It also highlights the key features of an effective arc-resistant MCC design.
Managing safety hazards and reducing risks are top priorities for manufacturers across all sectors of industry. With a multitude of potential dangers and new ones continuously emerging, companies must be diligent in their ongoing efforts while considering new approaches and technologies to improve plant safety. One rapidly growing area of focus is implementing techniques and practices designed to reduce hazards and minimize risk for workers who must enter an area with an electrical arc-flash potential.02/08/2010
We can tune PID controllers, but what about tuning the operator?
The purpose of tuning loops is to reduce errors and thus provide more efficient operation that returns quickly to steady-state efficiency after upsets, errors or changes in load. State-of-the-art manufacturers in process and discrete industries have invested in advanced control software, manufacturing execution software and modeling software to "tune" everything from control loops to supply chains, thus driving higher quality and productivity.
The "forgotten loop" has been the operator, who is typically trained to "average" parameters to run adequately under most steady-state conditions. "Advanced tuning" of the operator could yield even better outputs, with higher quality, fewer errors and a wider response to fluctuating operating conditions. This paper explores the issue of improving operator actions, and a method for doing so.
Over the past decade we've spent, as an industry, billions of dollars and millions of man-hours automating our factories and plants. The solutions have included adding sensors, networks and software that can measure, analyze and either act or recommend action to help production get to "Six Sigma" efficiency. However, few, if any, plants are totally automated. Despite a continuing effort to remove personnel costs and drive repeatability through automation, all plants and factories have human operators. These important human assets are responsible for monitoring the control systems, either to act on system recommendations, or override automated actions if circumstances warrant.
Most of the time, operators let the system do what it was designed and programmed to do. Sometimes, operators make errors of commission, with causes ranging from misinterpretation of data to poor training or errors of omission attributed to lack of attention or speedy response. An operator's job has often been described as hours of boredom interrupted by moments of sheer panic. What the operator does during panic situations often depends on how well he or she has been trained, or "tuned."02/08/2010
Applying virtualization technology to open industrial control systems reduces lifecycle costs and improves manageability. Virtualization helps reduce hardware and operating system (OS) changes, improve computer platform resource utilization and makes the system easier to maintain. Read this white paper to learn more.02/01/2010
This white paper discusses the "Smart Redundancy" capability of GEs revolutionary Quad PAC solution, which includes a patent-pending algorithm that continually calculates the relative system availability in real time and delivers predictive analysis to maintain maximum system availability.01/26/2010
"More" may be "less" when applied to safety systems architecture. Have the terms DMR, TMR and Quad become irrelevant in your safety system building vocabulary?01/26/2010
For those who work in or are suppliers to many of the process industries, the "heat" is always on plant equipment even during the cold of winter and the search to find ways to beat the heat when selecting plant instrumentation and controls that withstand rugged operating conditions continues. Air/gas flow meters are no exception. While performance, ease of installation, maintenance and other criteria are all important, flow meters must always be evaluated according to their operating environment and process conditions. These conditions often range from 500 to 850°F (260 to 454°C) in high temperature process industries. Download this white paper to learn more about selecting flowmeters for high temperature process industries.01/26/2010
This paper gives an overview of some basic criteria for choosing lining material for the water / wastewater industry and furthermore provides a short description of the properties, strengths and weaknesses of EPDM, NBR, PUR and Ebonite, i.e. the four types of lining material most commonly used in the water / wastewater industry.
Basic criteria for choosing lining material
Due to the functionality of the flowmeter, a non-conductive lining material is imperative, but other requirements vary according to the specific features of the intended application.01/25/2010
Understanding the accuracy of a given flowmeter is an important field but it can also be misleading as different specifications are used to explain how accurate a flowmeter measurement actually measures. This paper discusses the different specifications and interprets the impact of them.
Why deal with accuracy?
The reasons for dealing with flowmeter accuracy specifications are many-folded. One important reason is from an economical point of view. The more accurate a flowmeter can measure, the more money you will save as the medium is measured with only very little inaccurately.
E.g. If the medium is expensive such as oil, it is important to know exactly how much is consumed. This ensures it is being consumed as efficiently as possible. Another reason is in terms of dosing, where a given amount of a medium is added. This must be done with a high level of precision and the accuracy is thus important in order to dose correctly. This is critical in certain industries such as in pharma or chemical.01/25/2010
TVIS is a heat transmission company for the Trekantomradet geographical area of Denmark. It takes care of excess heat from the industries and power plants in the area and redistributes the heat in pipelines to households, public institutions, offices, shops and other facilities in the area. ABB in Denmark has supplied TVIS a SCADA solution based on System 800xA for controlling the district heating network. Read this white paper to learn how TVIS, in conjunction with ABB's new SCADA solution system, monitors heat transmissions remotely and safely.01/20/2010
ABB Review takes a look at the project in Petrobras REPAR refinery. This project is a stateoftheart electrical integration for a refinery, it uses System 800xA and IEC 61850. Download this white paper to learn how ABB accomplished this system integration.01/12/2010
Something happensa signal peaks or fallsand you need to know. A limit alarm trip triggers the response you need to maintain normal and safe operations. This white paper will show you how to back up your DCS and PLC "soft" alarms with the reliability of "hard" alarms.01/12/2010
Protection from noise and ground loops due to ISO-Channel architecture.
Precision measurement systems are often limited in that all inputs are connected to a single ground. Typically, multiplexer input configurations are set up this way, since all signal inputs are connected to the same return. Even differential input configurations use the same ground reference. The result is that accuracy and flexibility for accurate measurements can be severely compromised when noise or common mode voltage is present.
Crosstalk from one input signal can easily be reflected onto another input. The design movement to an A/D per channel can help this problem. But that is not sufficient in many cases.
To minimize noise and ground loops, some newer systems offer isolation between the input signal ground reference and the computer ground. This effectively separates the computer ground from the measurement portion of the system. But still, there is no isolation between input sensor channels, which is a common source of error and frustration for user applications. Why?01/06/2010
AMS2750D Temperature Uniformity Surveys using TEMPpoint.
Industrial process furnaces and ovens require uniform temperature and heating; This is critical to repeatable product performance from batch to batch. These furnaces require periodic inspection for temperature uniformity.
Electronic and Mechanical Calibration Services, Millbury Massachusetts characterizes temperature uniformity in industrial furnaces and ovens for their customers. This is accomplished by measuring temperature in several locations throughout the furnace and monitoring temperature with thermocouples over time according to AMS2750D specifications.
The customer previously used chart recorders which require constant monitoring while the survey is running. Surveys can run anywhere from 35 minutes to several hours long depending on the industry specified requirements. With the TEMPpoint solution the operator can set it up and let it run unattended, freeing them up to multitask their time and work more efficiently. The shipping TEMPpoint application required very little modification using Measure Foundry and now fulfills customer's requirements.01/06/2010
Everyone is familiar with the concept of temperature in an everyday sense because our bodies feel and are sensitive to any perceptible change. But for more exacting needs as found in many scientific, industrial, and commercial uses, the temperature of a process must be measured and controlled definitively. Even changes of a fraction of a degree Celsius can be wasteful or even catastrophic in many situations.
For example, some biotech processes require elevated temperatures for reactions to occur and added reagents require exactly the right temperature for proper catalytic action. New alloys of metal and composites, such as those on the new Boeing 787 Dreamliner, are formed with high temperature methods at exacting degree points to create the necessary properties of strength, endurance, and reliability. Certain medical supplies and pharmaceuticals must be stored at exactly the desired temperature for transport and inventory to protect against deterioration and ensure effectiveness.
These new applications have driven the hunt for more exacting temperature measurement and control solutions that are easy to implement and use by both novice users and experienced engineers alike. This is a challenging task. However, new equipment and standards, such as LXI (LAN Extensions for Instrumentation) offer a methodology to perform these exacting measurements in test and control applications.
Many LXI devices are available on the market today. But, what do you need to know to select the best temperature measurement solution for your test and control application? This paper describes the common pitfalls of precision temperature measurement and what you need to consider before selecting a temperature measurement solution.01/06/2010
Safety & Automation System (SAS) - How the Safety and the Automation Systems Finally Come Together as an HMI
Today we have clear guidelines on how the Safety Instrumented Systems (SIS) and basic Process Control Systems (BPCS) should be separated from a controls and network perspective. But what does this mean to the HMI and the control room design?
Where do Fire & Gas Systems fit into the big picture and what about new Security and Environmental monitoring tasks?
What does the Instrument Engineer needs to know about operators and how systems communicate with them.
The evolution of the control room continues as Large Screen Displays provide a big picture view of multiple systems. Do rules and guidelines exist for this aspect of independent protection layers? What are today's best practices for bringing these islands of technology together.
This paper will review the topic and provide advice on a subject on which the books remain silent. Today's practices are haphazard and left to individuals without a systematic design or guidance.
Over the past 20 years the Safety System and the Automation system have been evolving separately. They use similar technologies, but the operator interface needs to be just one system. Unfortunately, due to the nature of the designs, this is not the case.
The automation system has been evolving since the introduction of the DCS and many Human Factor mistakes have been made. As we move towards new standards such as ISA SP 101 a more formal approach to HMI design is being taken.
The past widespread use of black backgrounds which cause glare issues in the control room and are solely responsible for turning the control room lights down to very low levels, or in some cases off, are being replaced with grey backgrounds and a new grayscale graphic standard replacing bright colors for a more plain grayscale scheme only using color to attract the operators' attention.
In having strong compliance schemes that restrict color usage to just a handful of colors, restricting the use of some colors that are reserved for important information such as alarm status, it appears that the automation system is being standardized and is starting to take advantage of new technology available to control room designers such as large screen displays.01/06/2010
This white paper explains why application whitelisting is being rapidly adopted as a security and control solution for SCADA systems. In three major sections, the paper: 1) Provides a detailed perspective on how application whitelisting technology works. 2) Discusses the use and benefits of whitelisting technologies in SCADA and Energy environments. 3) Explains how the technology is adapting to function in environments where controlled software changes are needed.12/21/2009
Although multivariable control is now a wellestablished technology, new applications are still being found on which to apply it.In this paper, details will be presented on how Honeywells Profit Controller was found to be particularly applicable to the offshore production process.12/15/2009
Customers in all industries are coming more and more under pressure to measure the cost of their utilities. Important drivers for this pressure are the rising cost of energy and various certifications according to EMAS and the ISO 14000 series. Measuring utilities has been neglected in the past and using calibrated technology is necessary for this process. However, many companies only measure their utility consumption at the custody transfer point, and these few measuring occurrences leave room for inaccuracy and poor energy management. By investing money in efficient measuring tools, is possible to set up energy monitoring systems that measure the consumption of each respective utility close to the point of use. This white paper reviews processes that can help you attain better energy management. Download now to learn more.12/14/2009
Protecting your HMI/SCADA system is critical but can be challenging due to complex, multilayered technologies, cyber threats and other risks. This white paper describes where vulnerabilities within an HMI/SCADA system may lie and how companies can take proactive steps to address susceptible areas through securitybased software capabilities.12/11/2009