The last 10 years have seen a major expansion of the use of wireless data technology in every aspect of life and in every industrial venue. From the ubiquitous cell phone to smart phones, tablets and more, wireless data communications have become an important, perhaps the most important, medium. In the last half dozen years, wireless field devices have begun penetrating the industrial environment too. IT and plant floor communications managers are faced with a daunting task in coordinating all the uses of wireless in the average 21st-century plant.
As more and more wireless devices and applications become an integral part of the industrial arena landscape, concern grows over in which layer of the network these wireless devices should be placed. This question concerns everyone since this is sure to impact plant or plant operation in the near future.
We typically see two physical networks. The Process Control Network (PCN) involves Layers 2 and below. The Business Network (BN) involves Layer 4 of the Purdue model. If you are part of a plant team that supports either of these networks, the discussions within this paper have been or will be part of an ongoing discussion for your organization.
We've seen a number of major companies make an attempt to stake out where wireless devices will fall and under what level of the network. This paper addresses these types of issues and is intended to provide answers to the many questions that are sure to arise.
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
This White paper describes new technology and product applications that are enabling process control solutions that weren't possible before. New dual-sensor technology puts engineers in control with a small device that can be placed in-line where fluid characteristics measurement is needed.
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.
PD Flowmeters Quitely Excell 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.
IDC interviewed 100 manufacturers in the U.K., France and Italy to get more insights into their sustainability approaches. What was asked ranged from how sustainability was linked to business performance and how operational risk management and energy management can be improved to how product safety and compliance costs could be reduced. Download this white paper to find out more about how European manufacturers are tackling their sustainability efforts.
Today's manufacturing companies face many pressures, including rising costs for raw materials, labor and distribution, not to mention customer demands for higher quality at lower prices. This paper explores the use of today's recipe software solutions as a part of a control strategy to transform a company's recipe area from a place of contentious schedule adherence and "rollofthedice quality" to one that can reduce waste while increasing quality to provide a consistent schedule adherence in an environment for continuous improvement.
Download and learn how recipe solutions can improve a company's bottom line.
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.
More than 30 years ago, the Dow Chemical Co. embarked on what ultimately evolved into a global corporate initiative: to develop and broadly leverage a standardized, highly integrated process automation system, incorporating basic process control, process information and safety system functionality.
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.
The right automation solution can meet the goals of specialty chemicals producers by addressing needs for product reliability, quality, agility and efficiency the keys to a sustainable competitive advantage. It will also enable small sites to boost performance and agility, achieve reliability targets, improve quality and drive down costs. Download this white paper to learn more.
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 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.