Topic: Process Variables

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Sense When to Go Wireless
What's the Point of Trying to Add Wireless Capabilities to Sensors and Related Components?

Feedback Critical to Machining Precision
Vertical Turning/Grinding Machine Uses Optical and Magnetic Encoders to Aid High-Accuracy Production of Wind Turbine Bearings

Current Signal Conversion Experience
A Variable-Speed Drive for a 500 hp Cooling Tower Fan Gets Replaced, But the 'Setpoint' Sent via 4-20 mA Doesn't Modulate. Why?

Zero in on the Sensor Precision, Accuracy Target
Improvement in Both Areas Increases How Often a Machine Hits a Performance Bull's Eye

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White Papers: In Depth Research

Motion Control System Options Using EtherCAT Technology
Author: Karl Meier, business development for Advanced Motion Controls
Posted: 02/20/2013
This document describes the evolution of motion and control system architectures and what new benefits are realized today when using EtherCAT, whether for a large number of axes or simple systems using just a few. OEMs have many choices available and naturally gravitate to a given architecture in order to speed development and reduce cost. Machine systems, and mainly motion control, are normalized to meet the requirements of the application.

Highlighted too, is not only the rise and acceptance for network connected motion control applications, but also why they are here to stay. In fact, the continued demand for servo solutions like those provided by EtherCAT-based systems will grow faster than most others and come at lower costs to implement.

Dual Die Compensation for MEMS Pressure Sensors
Author: All Sensors
Posted: 12/26/2012
Several pressure sensor manufactures promote product incorporating "dual die compensation." This compensation technique is employed for very low-pressure sensors where common mode errors cannot be compensated by any other means, for either gage or differential pressure measurements.

There are two forms of dual die compensation. One form of dual die compensation incorporates two pressure sensors but only one of the two sensors provides a pressure sensitive output. The second sensor is passive and is used solely to correct for common mode errors. The second form of dual die compensation incorporates two pressure sensors and both sensors provide a pressure sensitive signal. Both these compensation techniques are embodied in patent 6,023,978. This compensation technique applies to all common mode errors and is the only technique available to compensate for long term drift of output offset voltage.

This white paper illustrates dual die compensation methods where common mode errors are reduced in comparison to traditional methods and illustrates a reference to traditional sensor construction where common mode errors are not reduced.

Probability and Redundancy
Author: Kristen Barbour, Pepperl+Fuchs
Posted: 03/30/2012

Process plants are striving now more than ever to reduce operational expenditures while increasing productivity and efficiency. Today's process engineers place a tremendous amount of emphasis on system integrity requirements. Why? Because it's a variable that can be controlled when the right equipment is in place.

System Integrity Requirements
System integrity: State of a system where it is performing its intended functions without being degraded or impaired by changes or disruptions in its internal or external environments.

System reliability is a calculation based on estimates. Certain procedures and component evaluations are used to predict the integrity of a given system or individual component. Each component of a system is evaluated individually and its probability of failure is estimated. The manner in which components are connected will influence the integrity of the system. For example a system component connected in series will have more probable impact on the system integrity than a more reliable parallel connection. Each component estimates are combined to provide an over all estimate to the probability of failure for a given system. Redundancy is used to add to the systems overall availability and reduce a given systems probability of failure.

Parallel Redundancy
Two or more system components are operating simultaneously. Only one component is required to be working for the system to operate, and it should continue to function at acceptable performance levels after the loss of any component. Both components must fail in order for a system failure.

Download the entire white paper to learn more.

Calculating total value of ownership for the OEM
Author: Rockwell Automation
Posted: 04/04/2007
This white paper argues that machine builders can highlight other features, like operational equipment efficiency (OEE), to determine a machine's worth.

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