There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of 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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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 purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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