So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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(Will be addressed in future versions of this book)
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath 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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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(Will be addressed in future versions of this book)
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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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Abdelaziz, Ahmed (June 2014) Identified numerous typographical errors throughout the book, mostly repeated…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred 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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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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A flow switch is one that detects the flow of some fluid through a pipe. Flow switches often use…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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 extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Light has long been used as a long-range signaling medium. While communication by light through open air is…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Process measurements are often of an analog nature: the temperature of a furnace, the rate of fluid flow…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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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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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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Steam boilers are very common in industry, principally because steam power is so useful. Common uses for steam…
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(Will be addressed in future versions of this book)
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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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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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