Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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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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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Coy, John J. et. al. (December 2012) Sampled graphic illustrations from his NASA Reference Publication…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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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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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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