By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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 electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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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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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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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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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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The final element of PID control is the “D” term, which stands for derivative. This is a calculus…
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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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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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