The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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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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The efficient identification and correction of instrument calibration errors is an important function for…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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