The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express 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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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 level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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