The two “process variables” we rely on most heavily in the field of electrical measurement and…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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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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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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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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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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 November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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(Will be addressed in future versions of this book)
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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Converting between disparate units of measurement is the bane of many science students. The problem is worse…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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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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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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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 limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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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 for any PID controller to be practical, it must be able to do more than just implement the PID…
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Feedback obtained from industrial users of FF reveal a common pattern: Fieldbus is a powerful and reliable…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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