The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as 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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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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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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on 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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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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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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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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Learn about Modbus function codes, the structure of Modbus message packets, and the various types of channels used to transmit Modbus telegrams between controllers.
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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Calculus. Few areas of mathematics are as powerfully useful in describing and analyzing the physical…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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