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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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 simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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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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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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