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 vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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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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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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(Will be addressed in future versions of this book)
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as 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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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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(Will be addressed in future versions of this book)
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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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 much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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An important design parameter of a control valve is the position it will “fail” to if it loses…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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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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The efficient identification and correction of instrument calibration errors is an important function for…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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