By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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(Will be addressed in future versions of this book)
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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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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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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