Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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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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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Take for instance the problem of measuring fluid flow through a pipe. To the layperson, this may seem to be a…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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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 wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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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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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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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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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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