One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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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 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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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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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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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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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting 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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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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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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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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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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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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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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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