An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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 bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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 great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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 control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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In modern industry, the most popular form of field-level signal transmission for variable industrial…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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 machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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