The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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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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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 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 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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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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 order for any PID controller to be practical, it must be able to do more than just implement the 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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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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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Many traditional flowmeter technologies respond to the volumetric flow rate of the moving fluid.…
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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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