There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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 simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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 key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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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 addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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 simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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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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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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In contrast to quantitative tuning procedures where definite numerical values for P, I, and D controller…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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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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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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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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