There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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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 basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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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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