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 following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Feedback Control System Components Before we begin our discussion on process control, we must define a few key…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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