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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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