Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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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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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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