Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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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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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as 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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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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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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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A fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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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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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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(Will be addressed in future versions of this book)
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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