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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The term “grid” refers to the conductors and equipment interconnecting power sources to power…
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Electrical power grids primarily consist of three-phase AC circuits. This means most power lines (transmission…
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The two “process variables” we rely on most heavily in the field of electrical measurement and…
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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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Disconnect Switches Disconnects are switches designed to isolate sections of a power system in case of damage…
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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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One of the fundamental laws of electric circuits is Kirchhoff’s Current Law, which states the algebraic…
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Three-phase AC is the dominant mode of electric power generation and distribution in modern societies.…
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Circuit breakers used in residential, commercial, and light industrial service are self-tripping devices: they…
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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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“Polyphase” means “many phases,” describing a form of AC electrical system where…
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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 form of protection against faults on long-distance power lines is called distance relaying, so named because…
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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 digital multimeter (DMM) is quite possibly the most useful tool in the instrument technician’s…
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As a general rule, high achievement only takes place in an atmosphere of high expectations. Sometimes these…
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The advent of “smart” field instruments containing microprocessors has been a great advance for…
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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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As defined previously, calibration means the comparison and adjustment (if necessary) of an instrument’s…
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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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Suppose we wished to measure the rate of propane gas flow through a hose to a torch: Flowmeters appropriate…
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RTDs are completely passive sensing elements, requiring the application of an externally-sourced electric…
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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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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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These fortifications focus on human behavior rather than system design or component selection. In some ways…
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Electrical Resistance Resistance (\(R\)) is the dissipative opposition to an electric current, analogous to…
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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 fundamental limitation of proportional control has to do with its response to changes in setpoint and…
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The following animation shows how the “rotating” magnetic field of a three-phase AC induction…
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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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A level switch is one detecting the level of liquid or solid (granules or powder) in a vessel. Level switches…
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The efficient identification and correction of instrument calibration errors is an important function for…
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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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Earlier in this chapter you were shown a model of a nitrogen atom with a dense nucleus (comprised of protons…
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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 unique form of differential pressure-based flow measurement deserves its own section in this flow…
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A much simpler alternative to continuous vibration sensors (displacement or acceleration) and monitoring…
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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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Cyber-security seems to have its own vocabulary, ranging from unwieldy technical acronyms to slang terms…
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The following animation shows the calculus concepts of differentiation and integration (with respect to time)…
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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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Stoichiometry is the accounting of atoms before and after a chemical reaction. It is an expression of the Law…
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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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One of the great benefits of digital technology is the ability to communicate vast amounts of information over…
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To show a practical process example, let’s examine three diagrams for a compressor control system,…
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Self-balancing pneumatic instrument mechanisms are very similar to negative-feedback operational amplifier…
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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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Capacitors store energy in electric fields, proportional to the square of voltage. Inductors store energy in…
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It is often useful to express the amplitude of an alternating quantity such as voltage or current in terms…
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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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To better understand the design and operation of self-balancing pneumatic mechanisms, it is helpful to examine…
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Much of our knowledge about atomic structure comes from experimental data relating the interaction between…
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Visualizing the actions of P, I, and D tuning parameters using graphs is extremely useful in predicting the…
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