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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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 limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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(Will be addressed in future versions of this book)
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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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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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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(Will be addressed in future versions of this book)
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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