Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express 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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A bridge circuit is basically a pair of voltage dividers where the circuit output is taken as the difference…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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 variety of problem-solving techniques have been presented for students over the years which are all helpful…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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In modern industry, the most popular form of field-level signal transmission for variable industrial…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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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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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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