Another category of control strategies involves the use of signal relays or function blocks with the ability…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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Control valves are supposed to deliver reliable, repeatable control of process fluid flow rate over a wide…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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As described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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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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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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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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A machine in the broad sense of the word is any device designed to translate some form of energy into useful…
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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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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Lipták, Béla G. et al., Instrument Engineers’ Handbook – Process Measurement and Analysis Volume I,…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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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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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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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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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float directly sets…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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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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A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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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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A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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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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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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