The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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 limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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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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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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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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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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