DC electric current signals may also be used to communicate process measurement information from transmitters…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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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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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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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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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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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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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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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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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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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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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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