The efficient identification and correction of instrument calibration errors is an important function for…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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 variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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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Binary patterns are not just able to represent numerical values. Given a standardized code, they may represent…
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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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In a manually-controlled process, a human operator directly actuates some form of final control element…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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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 pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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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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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Learning from reading printed text is a kind of problem-solving activity it is own right. The problem is how…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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A different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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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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There are many process control applications in the industry where it is desirable to have multiple control…
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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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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring 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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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Like so many other industrial data networks, FOUNDATION Fieldbus is an “unswitched” or…
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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 whole class of problem-solving techniques focuses on altering the given problem into a simpler form that is…
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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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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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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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DC electric current signals may also be used to communicate process measurement information from transmitters…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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Perhaps the most important rule of controller tuning is to know the process before attempting to adjust the…
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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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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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