A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one…
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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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The simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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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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Light is known to interact with matter in very specific ways, which may be exploited as a means of measuring…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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The reason why a pneumatic control valve’s stem position corresponds linearly to the amount of air…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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Most pneumatic instruments use a simple but highly sensitive mechanism for converting mechanical motion into…
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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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Hydrogen ion activity in aqueous (water-solvent) solutions is a very important parameter for a wide variety of…
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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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The disadvantages of pneumatic instruments are painfully evident to anyone familiar with both pneumatic and…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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Calculus has a reputation for being difficult to learn, and with good reason. The traditional approach to…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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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 term “grid” refers to the conductors and equipment interconnecting power sources to power…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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Any power grid large enough to meet the demand of an entire nation must have multiple generators drawing from…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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Flow, by definition, is the passage of material from one location to another over time. So far this chapter…
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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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