The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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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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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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