Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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 the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as 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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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(Will be addressed in future versions of this book)
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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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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(Will be addressed in future versions of this book)
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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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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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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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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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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