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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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 simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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 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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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(Will be addressed in future versions of this book)
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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 animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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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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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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