In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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(Will be addressed in future versions of this book)
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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 powerful mathematical concept useful for analyzing practically any physical system – electrical…
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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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A limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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One very convenient feature of waves is that their properties are universal. Waves of water in the ocean,…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Some problem-solving techniques are unique to quantitative problems, involving mathematical calculations. In…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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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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Shown here is a partial listing of principles applied in the subject matter of this chapter, given for the…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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Weight-based level instruments sense process level in a vessel by directly measuring the weight of the vessel.…
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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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An on/off valve is the fluid equivalent of an electrical switch: a device that either allows unimpeded flow or…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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A great many chemical composition measurements may be made indirectly by means of electricity, if those…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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I remember first learning about the world-wide Internet, and wondering what it actually looked like. The first…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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