As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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There are many process control applications in the industry where it is desirable to have multiple control…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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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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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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As we have seen, feedforward control is a way to improve the stability of a feedback control system in the…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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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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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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The dispersion of visible light into its constituent colors goes all the way back to the 17th century with…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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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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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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The final step in treating wastewater before releasing it into the natural environment is to kill any harmful…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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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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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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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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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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