A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as 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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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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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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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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 term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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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 discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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 electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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