A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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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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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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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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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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An important design parameter of a control valve is the position it will “fail” to if it loses…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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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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Diagnostic ability is arguably the most difficult skill to develop within a student, and also the most…
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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 different strategy for controlling the flow of fluid is to insert a rotary element into the flow path.…
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Disturbances in the liquid tend to complicate liquid level measurement. These disturbances may result from…
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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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Valve actuators provide force to move control valve trim. For precise positioning of a control valve, there…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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Capacitance Any two electrical conductors separated by an insulating medium possess the characteristic called…
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So far we have just looked at instruments that sense, control, and influence process variables. Transmitters,…
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Developed by the Modicon company (the original manufacturer of the Programmable Logic Controller, or PLC) in…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Many liquid substances undergo a process whereby their constituent molecules split into positively and…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Thermodynamics is the study of heat, temperature, and their related effects in physical systems. As a subject,…
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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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Learning is not merely a process of information transfer. It is first and foremost a transformation of…
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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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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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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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Measuring the flow rate of liquid through an open channel is not unlike measuring the flow rate of a liquid…
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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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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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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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The transformer is one of the most important components in all of AC circuitry. Principally used to…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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Instrument technicians should not have to concern themselves over the programming details internal to digital…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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A chemical reaction resulting in a net release of energy is called exothermic. Conversely, a chemical reaction…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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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 design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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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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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering 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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A form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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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A limit switch detects the physical motion of an object by direct contact with that object. An example of a…
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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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Filled-bulb systems exploit the principle of fluid expansion to measure temperature. If a fluid is enclosed in…
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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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Atom: the smallest unit of matter that may be isolated by chemical means. Particle: a part of an atom,…
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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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One of the most important accessories for any temperature-sensing element is a pressure-tight sheath known as…
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Labwork is an essential part of any science-based curriculum. Here, much improvement may be made over the…
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Negative feedback systems, in general, tend to cause confusion for those first learning their fundamental…
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