Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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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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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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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 much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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