DC electric motors generate torque by a reaction between two magnetic fields: one field established by…
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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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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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Displacer level instruments exploit Archimedes’ Principle to detect liquid level by continuously…
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The majority of flowmeter technologies operate on the principle of interpreting fluid flow based on the…
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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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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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By definition, a source is a device delivering energy into a system, while a load is a device extracting…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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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 order for any PID controller to be practical, it must be able to do more than just implement the PID…
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A very simple device used to measure pressure is the manometer: a fluid-filled tube where an applied gas…
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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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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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A pressure switch is one that detects the presence of fluid pressure. Pressure switches often use diaphragms…
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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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As we have seen, the concept of integration is finding the accumulation of one variable multiplied by another…
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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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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 laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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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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Up until this point, we have explored various types of instrumentation diagram, each one making reference 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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Many years ago, when I was first learning about electricity, I happened to discover a length of coaxial…
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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 4 to 20 mA current signal represents some signal along a 0 to 100 percent scale. Usually, this scale is…
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Solids tend to expand when heated. The amount that a solid sample will expand with increased temperature…
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Every programmable logic controller must have some means of receiving and interpreting signals from real-world…
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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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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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 two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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pH is the measurement of the hydrogen ion activity in a liquid solution. It is one of the most common forms of…
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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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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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When control valves operate between fully open and fully shut, they serve much the same purpose in process…
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A design-based fortification is one rooted in technical details of system architecture and functionality. Some…
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Learning how to tune PID controllers is a skill born of much practice. Regardless of how thoroughly you may…
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For better or worse, there are no fewer than three different forms of PID equations implemented in modern PID…
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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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Another category of control strategies involves the use of signal relays or function blocks with the ability…
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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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To summarize some of the key points and concepts for teaching: Do not waste class time transmitting facts to…
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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 great many precision instruments use the principle of balance to measure some quantity. Perhaps the simplest…
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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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Modern DC and AC motor drives provide features useful when using electric motors as final control elements.…
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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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This section does not describe a particular type of flowmeter, but rather a design that may be implemented for…
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Some self-powered (4-wire) analog electronic transmitters are designed to behave as electrical loads rather…
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Every flow-measuring instrument exploits a physical principle to measure the flow rate of fluid stream.…
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Perhaps the most valuable skill an instrument technician can possess is the ability to efficiently diagnose…
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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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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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Tube, like pipe, is a hollow structure designed to provide an enclosed pathway for fluids to flow. In the case…
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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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