The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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 key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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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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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. 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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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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To understand just how different FOUNDATION Fieldbus is from other digital instrument systems, consider a…
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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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