Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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There are many process control applications in the industry where it is desirable to have multiple control…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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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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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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(Will be addressed in future versions of this book)
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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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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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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(Will be addressed in future versions of this book)
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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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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