The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 order for any PID controller to be practical, it must be able to do more than just implement the PID…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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 limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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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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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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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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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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 unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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