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  • Advanced Process Control: Quick and Easy Energy Savings

    In today's manufacturing environment, there is an urgency to increase operating efficiencies, and to do it quickly. One area of improvement that can produce immediate results is reducing energy consumption. It's good for the environment and it's good for the bottom line. "Energy management," therefore, has become a common best practice, but there is more there than meets the eye. Typically it implies rigorously modeling all or a major portion of the plant, coupled with the use of real-time optimization technology. While this approach has been used successfully, there are other simpler, faster options for reducing energy consumption in a manufacturing plant. Learn what these options are.

    Paul Kesseler, Manager, Advanced Process Control Practice, Global Consulting Group, Invensys Operations Management
  • Achieving 21 CFR Part 11 Compliance Using CENTUM VP

    This technical white paper will discuss Yokogawa's CENTUM VP DCS (Distributed Control System) product, hereafter referred to as "CENTUM VP", and the extent of its compliance with Part 11 of Title 21 of the Code of Federal Regulations, (21 CFR Part 11), the Electronic Records / Electronic Signatures Rule.

    CENTUM VP Batch Management is the optional Batch control function for CENTUM VP, which provides recipe management and process management functionality based upon the ISA-88 Batch Control System standard. This whitepaper addresses the use of CENTUM VP and the Batch Management function.

    A detailed analysis of Part 11 was performed, the results of which are listed in the Detailed Part 11 Compliance section (section 5) of this document, which supports the compliance of the CENTUM VP system to Part 11.

    CENTUM VP is a comprehensive software package containing configurable functions that support Part 11 compliance (audit trails, electronic signatures and electronic records). The system capitalizes on its Part 11 compliance attributes in the marketing strategy of supplying FDA regulated industries with state of the art automation capabilities.

    User training and education as well as the development and utilization of policies and procedures are key components of Part 11 compliance which must be established by the user.

  • 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 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 Blueprint for the Real Time Enterprise

    Manufacturing and production processes have had to be controlled and managed in real time from inception because they change in real time frames. This has been a natural premise of industrial systems from the very beginning.

    A major shift in the business of manufacturing has occurred over the past decade which is driving the dynamics of the business of production and manufacturing into the real time domain. Business variables, such as energy prices, feedstock prices and even product prices have rapidly transitioned from highly transactional time frames into real time frames. For example, a decade ago it was not unusual for an industrial plant to establish a contract with its energy supplier that essentially set the price over an extended time period, of often 6 months or even a year. Today, in most parts of the world, long term fixed price energy contracts are not being offered and the price of energy can change multiple times in a day. The implications of this transition are clear. Industrial business functions must operate in real time to be effective and efficient. Industrial companies that do not move to real time business operations will be at a severe disadvantage in their marketplace.

    Invensys, Peter G. MartinInvensys, Peter G. Martin
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