Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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The efficient identification and correction of instrument calibration errors is an important function for…
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Constructing PID control systems using discrete components is a fairly simple method involving operational…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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 previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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Imagine a major marathon race, where hundreds of runners gather in one place to compete. When the starting gun…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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Finally, we arrive at the loop diagram (sometimes called a loop sheet) for the compressor surge control system…
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The next level of detail is the Process and Instrument Diagram, or P&ID. Here, we see a “zooming…
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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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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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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 following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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Fieldbus devices require far more attention in their initial setup and commissioning than their analog…
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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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A pneumatic controller receives a process variable (PV) signal as a variable air pressure, compares that…
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In addition to Ohm’s Law, we have a set of rules describing how voltages, currents, and resistances…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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The final element of PID control is the “D” term, which stands for derivative. This is a calculus…
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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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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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Perhaps the most important rule to obey when using pneumatic instruments is to maintain clean and dry…
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