AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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An important legacy technology for all kinds of continuous measurement is the self-balancing system. A…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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The following animation shows how a radio-energy pulse travels down and then up the waveguide of a guided-wave…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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A 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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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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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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DC electric current signals may also be used to communicate process measurement information from transmitters…
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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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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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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 simplest form of 4-20 mA current loop is the type used to represent the output of a process controller,…
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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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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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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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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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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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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Several different technologies exist for the conversion of fluid pressure into an electrical signal response.…
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Calculus. Few areas of mathematics are as powerfully useful in describing and analyzing the physical…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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A laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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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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Regulating the electric power sent to an electric motor is a task performed by high-speed switching…
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Most people reading this book have likely had the experience of adjusting water temperature using two hand…
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Given the ability of pressurized fluids to transmit force over long distances, it is not surprising that many…
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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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In order for any PID controller to be practical, it must be able to do more than just implement the PID…
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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 great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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(Will be addressed in future versions of this book)
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The three “elementary” particles of matter comprising all atoms are electrons, protons, and…
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