Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets 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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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 vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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Calculus. Few areas of mathematics are as powerfully useful in describing and analyzing the physical…
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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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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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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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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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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 whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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