Another category of control strategies involves the use of signal relays or function blocks with the ability…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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An important design parameter of a control valve is the position it will “fail” to if it loses…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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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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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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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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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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At the root of successful system diagnosis is a rigorous adherence to scientific reasoning. There exists no…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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