While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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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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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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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 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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