The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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Take for instance the problem of measuring fluid flow through a pipe. To the layperson, this may seem to be a…
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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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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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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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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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Take for instance the problem of measuring fluid flow through a pipe. To the layperson, this may seem to be a…
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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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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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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