As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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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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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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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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Capacitive level instruments measure electrical capacitance of a conductive rod inserted vertically into a…
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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 different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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A whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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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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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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 a manually-controlled process, a human operator directly actuates some form of final control element…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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An important design parameter of a control valve is the position it will “fail” to if it loses…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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A powerful mathematical concept useful for analyzing practically any physical system – electrical…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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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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First, let us review some of the properties of differentials and derivatives, referencing the expression and…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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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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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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 different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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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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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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