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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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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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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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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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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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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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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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