There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express 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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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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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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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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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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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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