Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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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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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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(Will be addressed in future versions of this book)
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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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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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