Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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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 discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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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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The efficient identification and correction of instrument calibration errors is an important function for…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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When I began teaching full-time in 1998, most of what I thought I understood about good teaching was actually…
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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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(Will be addressed in future versions of this book)
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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(Will be addressed in future versions of this book)
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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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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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