The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Multiple accessories exist for pressure-sensing devices to function optimally in challenging process…
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In reliability engineering, it is important to be able to quantity the reliability (or conversely, the…
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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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DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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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An important type of “accessory” relay, especially for legacy electromechanical protective relays,…
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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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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An electric motor is often used as a discrete control element in a control system if driving a pump, conveyor…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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There are several different methods useful for causing an AC induction motor to brake, or slow down: DC…
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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 great many chemical composition measurements may be made indirectly by means of electricity, if those…
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The digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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When a high-energy photon strikes an atom, it may eject one of the lower-level electrons from its shell,…
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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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In our first signal characterization example, we tackle the problem of measuring fluid flow through a pipe. To…
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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 pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Although analog electronic process controllers are considered a newer technology than pneumatic process…
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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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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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A completely different way of measuring liquid level in vessels is to bounce a traveling wave off the surface…
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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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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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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A variety of technologies exist to measure the quantity of stored material in a vessel. For liquid…
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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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The vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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Since we often use electricity to convey energy from one location to another, it is important to be able to…
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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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In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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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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Phasors are to AC circuit quantities as polarity is to DC circuit quantities: a way to express the…
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Sensors used to measure vibration come in three basic types: displacement, velocity, and acceleration.…
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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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Perhaps the simplest form of solid or liquid level measurement is with a float: a device that rides on the…
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A Safety Instrumented Function, or SIF, is one or more components designed to execute a specific…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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Suppose we wished to measure the consumption of propane over time for a large propane storage tank supplying a…
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Like many other mathematical operations, the derivative and the integral perform inverse operations from each…
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A quantitative PID tuning procedure is a step-by-step approach leading directly to a set of numerical values…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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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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(Will be addressed in future versions of this book)
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