Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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(Will be addressed in future versions of this book)
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(Will be addressed in future versions of this book)
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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PID control can be a confusing concept to understand. Here, a brief summary of each term within PID (P. I, and…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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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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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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(Will be addressed in future versions of this book)
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An exciting development in industrial instrumentation is the WirelessHART radio communication standard,…
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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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Self-balancing mechanisms consisting solely of a baffle/nozzle detector coupled to a feedback bellows, while…
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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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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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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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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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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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The following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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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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This animation shows the basic operation of a gas chromatograph, showing the separation of different molecular…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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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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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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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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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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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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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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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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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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A special type flowmeter suited for powdered or granular solids is the weighfeeder. One of the most common…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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