In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets 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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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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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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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 we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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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 three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy 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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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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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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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