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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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust 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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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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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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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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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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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 most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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The transformer is one of the most important components in all of AC circuitry. Principally used 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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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for 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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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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