A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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 key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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 simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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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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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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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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 simple control system drawn in block diagram form looks like this: Information from the measuring device…
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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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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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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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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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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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