The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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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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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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The final element of PID control is the “D” term, which stands for derivative. This is a calculus…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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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 very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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