White Papers

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  • A comparison of WirelessHART and ISA100.11a

    This paper provides a brief overview of WirelessHART and ISA100.11a standards, presents key differences between the standards, and concludes with a discussion on applications and application integration.

    Mark Nixon, Emerson Process Management
  • A DuPont Batch Automation Project Experience

    When presented with the problem of having to increase capacity 25% for a $100M/yr DuPont fluorochemical business, the solution was to fully automate the bottleneck of its supply chain, a batch process. Although the process already had a DCS, it was not nearly used to the potential it could be if additional instrumentation and automation software were installed. The journey taken to complete this solution taught us a lot about how to properly run a batch automation project. Upon completion of the project, we were presented another challenge. DuPont’s largest competitor withdrew from the market dramatically increasing product demand. With no additional capital, we were able to further increase capacity another 40%.

    John W. W. Wood Jr, Technical Engineer, DuPont; Vernon F. Morenas, R&D Engineer, DuPont
  • A Hybrid 18-Pulse Rectification Scheme for Diode Front End Variable Frequency Drives

    Diode rectifier with large DC bus capacitors, used in the front ends of Variable Frequency Drives (VFDs), draw discontinuous current from the power system resulting in current distortion and hence voltage distortion. Typically, the power system can handle current distortion without showing signs of voltage distortion. However, when the majority of the load on a distribution feeder is made up of VFDs, current distortion becomes an important issue. Multi-pulse techniques to reduce input harmonics are popular because they do not interfere with the existing power system either from higher conducted EMI when active techniques are used or from possible resonance, when capacitor based filters are employed.

    In this paper, a new 18-pulse topology is proposed that has two six-pulse rectifiers powered via a phase-shifting isolation transformer, while the third six-pulse rectifier is fed directly from the AC source via a matching-impedance. This idea relies on harmonic current cancellation strategy rather than the flux cancellation method and results in lower overall harmonics. It is also seen to be smaller in size and weight, and lower in cost compared to an isolation transformer. Experimental results are given to validate the concept.

    Mahesh Swamy, Tsuneo J. Kume and Noriyuki Takada, Yaskawa Electric America
  • A path forward for DCS alarm management

    Despite the recent industry focus on higher-level solutions, substantive technical challenges still abound in DCS alarm management. The reasons, importance, and solutions for the problem of alarm management are the subject of this White Paper.

    Plant Automation Services
  • A Perspective on Standards

    This whitepaper by Rockwell Automation, explores how companies can gain competitive advantage by increasing their standards and regulations involvement.

    Rockwell Automation
  • A Place For Positive Displacement

    PD Flowmeters Quietly Excel in Low-Flowrate, High Viscosity, and Liquid and Gas Metering Applications

    Positive displacement (PD) flowmeters are the workhorse of today's flowmeter world. They perform many important flow measurements most people take for granted. For example, they are widely used for metering both water and gas in residential, commercial, and industrial applications. Chances are good the flowmeter that measures how much water you use at your house is a PD meter.

    Positive Displacement

    Jesse Yoder
  • A Simple Single Setting Controller Yields PI Performance

    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 [1] 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 controller’s performance. In section 5 we will set forth the conclusions.

    Robert L Heider, PE, & Zachary Wegmann
  • A Systematic Approach To Plantwide Control

    This paper summarizes Sigurd Skogestad's struggles in the plantwide control field.

    A chemical plant may have thousands of measurements and control loops. By the term plantwide control it is not meant the tuning and behavior of each of these loops, but rather the control philosophy of the overall plant with emphasis on the structural decisions. In practice, the control system is usually divided into several layers, separated by time scale.

    My interest in this field of plantwide control dates back to 1983 when I started my PhD work at Caltech. As an application, I worked on distillation column control, which is excellent example of a plantwide control problem. I was inspired by Greg Shinskey's book on Distillation Control, which came out with a second edition in 1984 (Shinskey, 1984). In particular, I liked his systematic procedure, which involved computing the steady-state relative gain array (RGA) for 12 different control structures ("configurations"); the DV-configuration, LV-configuration, ratio configuration, and so on. However, when I looked in more detail on the procedure I discovered that its theoretical basis was weak. First, it did not actually include all structures, and it even eliminated the DB-configuration as "impossible" even through it is workable in practise (Luyben, 1989). Second, controllability theory tells that the steady-state RGA by itself is actually not useful, except that one should avoid pairing on negative gains. Third, the procedure focused on dual composition control, while one in practise uses only single end control, for example, because it may be optimal economically to use maximum heating to maximize the recovery of the valuable product.

    Sigurd Skogestad, Norwegian University of Science and Technology (NTNU)
  • A User’s Guide to Pressure Measurement

    A Complete Precision Pressure Measurement Handbook Covering the Fundamentals of Pressure Measurement, Deadweight Pressure Testers, Calibration of Deadweight Testers, AMETEK's Deadweight Testers, Manometers, Secondary Comparison Pressure Standards and the Selection of a Pressure Measurement Standard.

  • A User’s Wishlist for Batch

    The benefits of applying the S88.01 standard have been well proven in the industry, although most users have only scratched the surface on achieving these benefits. Some of this dilemma can be attributed to poor application of the standard by users; much can be traced to deficiencies in current tools that are available to the user. The S88.01 batch control standard has been around for five years. Ample time has been available to allow the appropriate tools to be developed that will allow users to take full advantage of the S88.01 standard. Most tools still do not provide enough needed features and flexibility. This paper will discuss ways of improving user application of the S88.01 standard and some of the deficiencies of currently available tools.

    Thomas G. Fisher, Operations Technology Manager, The Lubrizol Corporation
  • Accelerate Six Sigma Success

    Manufacturers are under extreme pressure to increase operational efficiency as a means to increase reliability and maintain margins. Six Sigma is providing a powerful means for companies to improve performance. The use of this methodical, statistics-based approach is increasing across a range of industries. Those in the process industries are discovering the PI System can provide critical support to Six Sigma teams at every step of their effort. This paper discusses how to the PI System can support a Six Sigma initiative. QNI, an Australian minerals resource company, serves as an example.

    OSIsoft Inc.
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