A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Much has been written about the benefits of robust PID control. Increased productivity, decreased equipment…
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Level gauges are perhaps the simplest indicating instrument for liquid level in a vessel. They are often found…
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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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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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An extremely important topic in engineering is that of transfer functions. Simply defined, a transfer function…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Two extremely important principles in electric circuits were codified by Gustav Robert Kirchhoff in the year…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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Certain types of nuclear radiation easily penetrates the walls of industrial vessels, but is attenuated by…
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A proximity switch is one detecting the proximity (closeness) of some object. By definition, these switches…
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While the term “probability” may evoke images of imprecision, probability is in fact an exact…
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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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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 advent of “smart” field instruments containing microprocessors has been a great advance for…
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Human-machine interfaces, or HMIs, are a critical part of nearly all control systems, complementing the…
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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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A number of different sensors used in instrumentation generate DC voltage signals proportional to the process…
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Linearity of Measurement Instruments The purpose of calibration is to ensure the input and output of an…
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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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In some process applications, it is important that the control valve be able to completely stop fluid flow…
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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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Any conductor possesses a characteristic called inductance: the ability to store energy in the form of a…
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Imagine a liquid-level control system for a vessel, where the position of a level-sensing float sets the…
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Non-dispersive analysis, while newer in discovery than dispersive analysis (Isaac Newton’s 17th-century…
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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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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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 simple PLC ladder diagram (LD) commands consist of contacts and coils, arranged in sequences that mimic…
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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 laser is a light source emitting waves of light that not only share the exact same frequency (color)…
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A sliding-stem valve body is one where the moving parts slide with a linear motion. Some examples of…
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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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Some analyzers measure the composition of a process stream by directly immersing the sensing element in that…
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One of the simplest classes of temperature sensor is one where temperature effects a change in electrical…
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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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The very purpose of physics is to quantitatively describe and explain the physical world in as few terms as…
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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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It is possible to convey electrical power and communicate analog information over the same two wires using 4…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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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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The most popular form of signal transmission used in modern industrial instrumentation systems (as of this…
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The fundamental principle of electromagnetism is that an electric current will create a magnetic field at…
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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 is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Control strategies such as cascade, ratio, feedforward, and those containing limit and selector functions can…
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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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A control strategy similar to ratio control is relation control. This is similar to ratio control in that a…
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All substances are comprised of various elements in various combinations and proportions. Elements may thus be…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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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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As previously defined, calibration refers to the checking and adjustment of an instrument so that its output…
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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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Sometimes we encounter a diversity of instrument signal standards in one control system. Such is the case with…
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