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 simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing 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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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(Will be addressed in future versions of this book)
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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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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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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(Will be addressed in future versions of this book)
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Sample sizes of chemical substances are often measured in moles. One mole of a substance is defined as a…
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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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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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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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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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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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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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