As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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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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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 addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express 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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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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 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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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A great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing 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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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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 positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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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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