The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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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…
Textbook
Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
Textbook
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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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 important rule of controller tuning is to know the process before attempting to adjust the…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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