A wise PLC programmer once told me that the first thing any aspiring programmer should learn about the PLC…
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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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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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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 term “grid” refers to the conductors and equipment interconnecting power sources to power…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Layer 1 of the OSI Reference Model is where we define the “physical” elements of a digital data…
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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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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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In modern industry, the most popular form of field-level signal transmission for variable industrial…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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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 chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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Regardless of valve type, all stem-actuated control valves require some form of seal allowing motion of the…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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 very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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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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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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Process analyzers measure the concentration of specific substances for the purpose of measuring and/or…
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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 electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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A very common method for directly controlling low flow rates of fluids is to use a device known as a metering…
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Most of these formulae appear in molecular chemical form rather than structural form. For example, ethanol…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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