There is much to be said for neatness of assembly in electrical signal wiring. Even though the electrons…
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In addition to directly performing logic functions, electromechanical relays may also be used as interposing…
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Learning PLC programming is a very important skill. If your job involves programming, then you will likely…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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Modern analog-to-digital converters are phenomenally accurate, dependable, repeatable, and surprisingly…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering in…
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Classical mechanics (often called Newtonian mechanics in honor of Isaac Newton) deal with forces and motions…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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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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Perhaps the most basic and necessary protective relay function is overcurrent: commanding a circuit breaker to…
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Virtually any mass above absolute zero temperature emits electromagnetic radiation (photons, or light) as a…
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In the United States, the ANSI and IEEE organizations have standardized a set of numerical codes referring to…
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Those familiar with industrial instrumentation will find much within the electric power industry remarkably…
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All masses require force to accelerate (we can also think of this in terms of the mass generating a reaction…
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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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Creative Commons Attribution 4.0 International Public License By exercising the Licensed Rights (defined…
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Although it seems each model of PLC has its own idiosyncratic standard for programming, there does exist an…
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A unique form of technical diagram for describing the abstract functions comprising a control system (e.g. PID…
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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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At the next OSI Reference Model layer (layer 4) is a set of protocols specifying how reliable communication…
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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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An electromechanical relay is an electrical switch actuated by an electromagnet coil. As switching devices,…
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Using filter cells to eliminate wavelengths associated with interfering gases is called positive filtering 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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Recall that an exothermic chemical reaction is one that releases a net sum of energy, as opposed to an…
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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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A unique form of differential pressure-based flow measurement deserves its own section in this flow…
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An important performance parameter for transmitter instruments is something often referred to as turndown or…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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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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A flow switch is one detecting the flow of some fluid through a pipe. Flow switches often use…
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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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This section shows some of the many instrument symbols found in different types of technical diagrams used to…
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A positive displacement flowmeter is a cyclic mechanism built to pass a fixed volume of fluid through with…
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Programmable logic controllers are essentially nothing more than special-purpose, industrial computers. As…
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Perhaps the most confusing aspect of discrete sensors is the definition of a sensor’s normal status.…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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In November of 2007 a new computer virus was submitted to a virus scanning service. The purpose of this new…
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The Law of Mass Conservation states that matter can neither be created nor destroyed. The Law of Energy…
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“As to methods there may be a million and then some, but principles are few. The man who grasps…
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A fluid is any substance having the ability to flow: to freely change shape and move under the influence of a…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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Electromechanical relays may be connected together to perform logic and control functions, acting as logic…
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The following collection of photographs chronicles the complete disassembly of a Fisher E-body globe valve…
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Temperature measurement devices may be classified into two broad types: contact and non-contact. Contact-type…
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A simple control system drawn in block diagram form looks like this: Information from the measuring device…
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Process measurements are often of an analog nature: the temperature of a furnace, the rate of 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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To review, voltage is the measure of potential energy available to electric charges. Current is the uniform…
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Data-processing modules within FF systems are known as function blocks. Sometimes these blocks serve merely to…
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A vertical column of fluid generates a pressure at the bottom of the column owing to the action of gravity on…
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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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“Feedforward” is a rather under-used control strategy capable of managing a great many types of…
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In this section I will show screenshots from a process loop simulation program illustrating the effectiveness…
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While 50 and 51 (instantaneous and time overcurrent) relay functions monitor line current magnitude and guard…
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The purpose of a control valve actuator is to provide the motive force to operate a valve mechanism. Both…
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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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