Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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 simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets 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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express 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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A limit switch detects the physical motion of an object by direct contact with that object. An example of 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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing 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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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There are many process control applications in the industry where it is desirable to have multiple control…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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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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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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