Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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The efficient identification and correction of instrument calibration errors is an important function for…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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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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(Will be addressed in future versions of this book)
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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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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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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(Will be addressed in future versions of this book)
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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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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There are multiple motives for compromising the security of an industrial control system, some of which…
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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 fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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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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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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