Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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Take for instance the problem of measuring fluid flow through a pipe. To the layperson, this may seem to be a…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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A machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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