“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Current is the name we give to the motion of electric charges from a point of high potential to a point of low…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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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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In the United States, the most common language used to program PLCs is Ladder Diagram (LD), also known as…
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The Law of Continuity for fluids states that the product of mass density (\(\rho\)), cross-sectional pipe area…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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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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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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Any physical location in an industrial facility harboring the potential of explosion due to the presence of…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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An variable-area flowmeter is one where the fluid must pass through a restriction whose area increases with…
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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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The simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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One of the marks of a successful problem-solver is a habit of applying general principles to every new problem…
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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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An engineer named Bob Metcalfe conceived the idea of Ethernet in 1973, while working for the Xerox research…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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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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The following animation shows a rotating phasor in three-dimensional form. The phasor rotates in a complex…
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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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Up until this point, we have explored various types of instrumentation diagram, each one making reference to…
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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 reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Few areas of mathematics are as powerfully useful in describing and analyzing the physical world as calculus:…
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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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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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A pressure switch is one detecting the presence of fluid pressure. Pressure switches often use diaphragms or…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Fluid pressure exerts force on any surface area it contacts, as described by the formula \(F = PA\). One…
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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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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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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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One of the most common, and most useful, pressure measuring instruments in industry is the differential…
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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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 very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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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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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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