Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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(Will be addressed in future versions of this book)
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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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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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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