RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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The efficient identification and correction of instrument calibration errors is an important function for…
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A technological advance introduced in the late 1980’s was HART, an acronym standing for Highway…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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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As discussed at the beginning of this chapter, instrumentation safety may be broadly divided into two…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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As we have seen, the concept of differentiation is finding the rate-of-change of one variable compared to…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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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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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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There are many process control applications in the industry where it is desirable to have multiple control…
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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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An interesting parallel to the “unity fraction” unit conversion technique is something referred to…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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 described earlier in this chapter, calibration refers to the adjustment of an instrument so its output…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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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A very common form of on/off valve used for pneumatic and hydraulic systems alike is the solenoid valve. A…
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Nearly every technical course teaches and tests students on definitions, basic concepts, and at least some…
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Area refers to the size of two-dimensional surface. Volume refers to the size of a three-dimensional space. To…
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A hand switch is exactly what the name implies: an electrical switch actuated by a person’s hand motion.…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Once while working as an instrument technician in an aluminum foundry, a mechanic asked me what it was that I…
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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 following photograph shows a large air blower in a wastewater treatment facility equipped with a…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Impedance in a series circuit is the orthogonal sum of resistance and reactance: \[Z = \sqrt{R^2 + (X_L -…
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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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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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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 to methods there may be a million and then some, but principles are few. The man who grasps…
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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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There are multiple motives for compromising the security of an industrial control system, some of which…
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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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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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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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AC induction motors are based on the principle of a rotating magnetic field produced by a set of stationary…
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(Will be addressed in future versions of this book)
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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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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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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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What is Calibration? To calibrate an instrument means to check and adjust (if necessary) its response so the…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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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 limitation inherent to pneumatic valve actuators is the amount of air flow required to or from the actuator…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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