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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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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 vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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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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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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