In order to provide an interface between the internal (digital) world of a computer and the external (analog)…
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The electrical conductivity of liquids is an important analytical measurement in many industrial processes.…
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Volumes could be written about poor diagnostic technique. The following mistakes are not intended to comprise…
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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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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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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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In a manually-controlled process, a human operator directly actuates some form of final control element…
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Pipe is a hollow structure designed to provide an enclosed pathway for fluids to flow, usually manufactured…
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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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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An important design parameter of a control valve is the position it will “fail” to if it loses…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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Valves can experience a number of problems, most of them either preventable or repairable. These problems can…
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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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(Will be addressed in future versions of this book)
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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Some of the simplest types of digital communication networks found in industry are defined by the EIA…
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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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“Radio” systems use electromagnetic fields to communicate information over long distances through…
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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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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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The concepts of calibration (trimming) and ranging are often difficult for new students of instrumentation to…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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A temperature switch is one detecting the temperature of some substance. Temperature switches often use…
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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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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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A variety of problem-solving techniques have been presented for students over the years which are all helpful…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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A damper (otherwise known as a louvre) is a multi-element flow control device generally used to throttle large…
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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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Mechanical pressure-sensing elements include the bellows, the diaphragm, and the bourdon tube. Each of these…
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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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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 vast majority of modern process transmitters (both analog and digital) come equipped with a feature known…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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The key to understanding how three-phase electric motors work is to have an accurate mental picture of the…
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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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The vast majority of PID controllers in service today are digital in nature. Microprocessors executing PID…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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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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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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