An important performance parameter for transmitter instruments is something often referred to as turndown or…
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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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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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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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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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 positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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An important design parameter of a control valve is the position it will “fail” to if it loses…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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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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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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A machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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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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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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