Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing 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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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