A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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In modern industry, the most popular form of field-level signal transmission for variable industrial…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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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 simple control system drawn in block diagram form looks like this: Information from the measuring device…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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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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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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