glossary of electrical and electronics engineering most of the terms listed in wikipedia glossaries are already defined and explained within wikipedia itself however glossaries like this one are useful for looking up comparing and reviewing large numbers of terms together you can help enhance this page by adding new terms or writing definitions for existing ones this glossary of electrical and electronics engineering pertains specifically to electrical and electronics engineering for a broad overview of engineering see glossary of engineering electrical engineering history outline glossary category portal vte a ac adapter an external power supply for portable devices that allows them to operate from wallsocket electricity ac power plugs and sockets electrical connectors used with alternating current ac power electric power where the current reverses direction periodically acac converter a power converter where the input and output are both alternating current but may differ in frequency or other characteristics acdc receiver design a radio receiver that can operate from either alternating current or direct current wall socket power acdc conversion rectification of ac current so that current flows in only one direction active rectification a circuit where rectifier devices are externally controlled to change ac to current flowing in one direction actuator an end device of a control system that manipulates a physical variable such as a valve opening or position of a machine part adaptive control a control strategy where parameters are adjusted as the controlled process changes adjustablespeed drive control for a motor that allows more than one speed to be selected advanced ztransform a mathematical technique used to model and analyze digital systems affinity laws mathematical formulas that relate the speed flow and diameter of pumps fans blowers and turbines useful for predicting output under varying conditions agbioeletric a brand name of a kind of vegetable oil for use in transformers aiee american institute of electrical engineers predecessor organization to ieee alphabeta transformation a mathematical technique useful in analysis of threephase circuits altair 8800 an early microcomputer alternating current electric current that reverses direction periodically alternator an electrical machine that converts mechanical power into ac electric power alternator synchronization the process of synchronizing an alternator to a grid or another alternator aluminium smelting reduction of aluminium ore to metal by use of large amounts of electric power ammeter an instrument that measures electric current amorphous metal transformer a power transformer where the metallic core is made of metals cooled so quickly that they do not form a crystal structure such transformers can reduce some kinds of energy loss ampacity current carrying capacity of a conductor in the context of electric power wiring ampere the si unit of electrical current ampres circuital law the mathematical relation between the integral of the magnetic field over some closed curve to the current passing through the region bound by the curve ampres force law the mathematical relation between the force between two current carrying conductors and the current flowing in them ampres law ampres circuital law amplidyne an electric machine that allows a small current to control a much larger current amplifier an system that produces an output that replicates an input signal but with a larger magnitude amplitude modulation transmission of information by changing the magnitude of a carrier signal for example sending sound by radio analog circuit a circuit where currents and voltages vary continually within some practical range in proportion to some signal analog filter an analog circuit that alters some frequencyrelated property of a signal analog signal processing generally techniques used to alter signals that rely on voltages or currents that vary continually over a practical range analog signal a signal whose properties current voltage vary proportionally to the information transmitted analogtodigital converter a circuit that produces a number proportional to the magnitude of a voltage or current anode the terminal of an electrochemical or electronic device through which conventional current flows inward antenna radio a structure which converts between electromagnetic waves in space and currents in a conductor apparent power in an alternating current power circuit the product of the magnitude of rms voltage and current apple computer a company that makes mobile telephones and computers arbitrary waveform generatora type of signal generator that can generate almost any waveform arc converter a device once used to generate radio waves arc furnace a furnace that melts material by use of an electric arc arc lamp an electric lamp that generates light from an electric arc arc welder a device used to join metals by melting them with an electric arc armature electrical engineering that part of an electrical machine that converts electrical energy to mechanical energy or vice versa artificial intelligence a computer system that replicates some feature of human intelligence artificial neural networks an electrical network that mimics the function of a biological nervous system asymptotic stability a condition of a control system where the output eventually reaches a steadystate value in response to any input asynchronous circuit a digital circuit where states propagate through a circuit without a synchronizing clock impulse audio and video connector an electrical fitting used to connect cables carrying audio or video signals audio equipment equipment used to handle signals at frequencies within the human range of hearing audio filter a circuit intended to alter some frequencyrelated property of a signal carrying sound information audio frequency a signal whose frequency is within the range of human hearing audio noise reduction reduction of interfering signals in an audio signal audio signal processing alteration of any properties of a signal carrying sound information dynamic range frequency response or others audion tube an early three electrode vacuum tube that had amplifying properties austin transformer a kind of isolation transformer automatic gain control a circuit that automatically adjusts the magnitude of a signal to prevent it from becoming too small or too large automatic transfer switch an electrical switch used to automatically select a standby source of electrical power when the principal source is lost automation automatic control of a process autorecloser a circuit protection device for overhead power distribution lines which briefly interrupts a circuit when a fault is detected then restores the circuit in the expectation the fault has cleared autotransformer a transformer where the primary and secondary circuits share some of the transformer windings availability factor the fraction of time that a power plant is available to produce power avalanche diode a diode intended for regular operation in the reverse avalanche breakdown mode used as a voltage reference noise source and in certain classes of microwave oscillator device average rectified value the average value of an alternating current waveform taking the absolute value of the waveform the average value is generally different from the rootmeansquare value contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links b backward wave oscillatora type of microwave oscillator vacuum tube balanced linea transmission line with two conductors with equal impedances to earth ground ball bearing motora conceptual motor that does not use electromagnetism baluna device that connects a balanced transmission line to an unbalanced line bandpass filtera filter that lets through signals within a range of frequencies bandstop filtera filter that blocks signals with a particular range of frequencies bandwidth signal processingthe range of frequencies over which a system generates or uses significant signal power bangbang controla controller that switches a final element on or off instead of providing a proportional response barlows wheela demonstration of electromagnetic principles bartletts bisection theorema mathematical theorem used in network analysis base load power plantan electric power plant that furnishes the part of load that does not vary during a day battery electricityan electrochemical device that produces electric power from chemical reactions battery eliminatoran ac adapter which allows battery operated equipment to run on wallsocket ac power bayer filteran optical filter used in color digital cameras beam tetrodea type of vacuum tube with four active elements plus a pair of beam forming plates beat frequencya frequency produced by nonlinear mixing of signals at two other frequencies bell telephone laboratoriesformerly the research and development laboratory of the american telephone and telegraph corporation biasingthe practice of setting the quiescent operating conditions of an amplifying device to obtain desired response bibo stabilitya control system that produces finite outputs for any finite input bilinear transforma mathematical technique to obtain the parameters for a digital filter to duplicate the response of some analog filter transfer function bimetallic stripa temperature sensing element made of two metals that have different coefficients of expansion intimately bonded together biotsavart lawthe mathematical relationship between a magnetic field and the current producing that field bipolar junction transistora type of transistor with two kinds of charge carriers blocked rotor testa test of an electric machine where the machine is energized but the shaft is prevented from turning bluray disca type of optical disc written and read using a blueviolet laser bode plota plot of the amplitude and phase frequency response of a system where the actual response is approximated by straight line segments boolean algebra logica type of algebra that deals with values that can only hold values true and false of great use in design and analysis of digital systems boost converterany power converter circuit that can produce an output voltage larger than its input voltage booster electric powera device used to increase voltage on an electric power distribution system such as a motorgenerator set on a dc system bound chargeelectric charge in a material that is not free to move through the material braking choppera device used to absorb energy from a motor to slow it down branch circuitin building wiring any circuit from the main panelboard to utilization equipment or receptacles breakdown voltagethe maximum voltage a device can withstand without damage bridge rectifiera set of rectifier diodes used to convert alternating current to direct current broadcastingtransmission of a signal to many receivers brush electrica sliding electrical contact between a moving part and a stationary part brushed dc electric motoran electric motor with brushes brushless dc electric motoran electric motor without brushes buchholz relaya gas pressure sensing device for protection of oilfilled transformers buck converterany power converter circuit that produces an output voltage less than its input voltage buckboost converterany power converter circuit that can provide a voltage greater or less than its input voltage buckboost transformera transformer that can be used to adjust voltage busbara set of conductors used to distribute current to many branches bushing electricalan electrical fitting used to connect external conductors to the interior of apparatus butterworth filtera type of filter with the flattest possible pass band buzzeran electromechanical or electronic device that produces a sound when energized contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links c canadian electrical codethe technical standard for building wiring in canada canadian standards associationnonprofit organization that develops electrical and other technical standards capacitancethe ability of a body to hold an electrical charge capacitoran electrical component that stores energy in an electric field capacitorinput filtera power supply network where a capacitor is the first element following the rectfier capacitor voltage transformerin electrical power systems an instrument transformer for measuring voltage that uses a capacitive voltage divider capacity factorthe ratio of energy produced by a power plant over some period over its maximum possible energy production in that time carrier currenta system for communications where a carrier signal is impressed on power line wiring carrier wavea radio wave that can be modulated changed systematically to carry information to a receiver category 3 cablea performance standard for unshielded twisted pair cables for analog voice and low speed data circuits within a building category 5e cablea performance standard for unshielded twisted pair cables for telephone and data within a building category 6 cablea performance standard for unshielded twisted pair cables for telephone and high speed data within a building catenarya geometric form of curve the shape of a uniform cable hanging between two supports cathode ray oscilloscopean electronic instrument that displays the wave shape of electrical signals on a cathode ray tube cathode ray tubea vacuum tube that relies on an electron beam usually used to render images on a fluorescent screen such as in television sets cathodethe terminal of an electrochemical or electronic device from which conventional current exits the device catswhisker detectora radio detector that uses a manuallyset whisker contact to a crystal of galena or other material to form a rectifying junction catvcable television distribution of television programming over a wire instead of by radio broadcast cavity magnetrona vacuum tube that is a high power microwave oscillator using a resonant cavity and electrons traveling through a magnetic field ccfl invertera power supply to generate the voltages required to operate a cold cathode fluorescent lamp cda compact disc used to store digital data or digitally recorded sound using an infrared laser center tapa connection on a transformer which has equal voltage to either end of the transformer winding ceramic resonatora piezoelectric element used to stabilize the frequency of an oscillator channel communicationsany communication path between a signal transmitter and a signal receiver or a preselected operating frequency for a radio system charactrona kind of text display vacuum tube that used an internal element to shape an electron beam to represent the shape of letters and other symbols charge pumpa dc to dc converter circuit that uses capacitors to store energy between stages charge transfer switcha kind of charge pump circuit chargecoupled devicean imaging sensor or data storage device that represents a signal or pixel by the charge stored in a capacitor and is able to move that charge from one capacitor to the next chebyshev filtera form of filter that has a steep frequency selective characteristic choke electronicsan induction coil used to block alternating current and pass direct current or to block high frequencies and pass lower frequencies chopper electronica circuit that switches on and off at a high rate used either for power conversion or to convert a dc signal to a more easily processed ac signal circle diagrama representation of the voltage and current characteristics of an electrical machine the plot traces out a circle or part of a circle circuit breaker panela distribution board for electric power that uses circuit breakers as protective elements circuit breakeran automatically operated electrical switch that opens to interrupt a short circuit or other fault circuit theorythe mathematical theory of electrical circuits circuit total limitation ctla us national electrical code rule for the number of circuits in a panel board clamp meteran ammeter that measures current with a split core that can be clamped on a wire clapp oscillatoran electronic oscillator circuit that uses three capacitors and an inductor class of accuracy in electrical measurementsa measure of the error produced by an electrical measuring instrument closedloop controllerany controller that manipulates some process variable to minimize the difference between the current state of the variable and the desired set point such as temperature flow or others coaxial cablea cable with an inner conductor centered inside a flexible tubular conductor used for radio frequency transmission lines cockcroftwalton generatora kind of circuit for generating very high dc voltage cogenerationproduction of electricity along with some other desired product such as process steam or desalinated water cold cathodean element of a vacuum tube that emits electrons without a heating circuit colossus computera british code breaking system used during world war ii combined cyclea thermal power plant that improves efficiency with two different kinds of energy extraction from the combustion products gas stream such as a gas turbine followed by a steam boiler communication systema system intended to convey information from one place to another with an expected degree of performance communications satellitea satellite in earth orbit designed for international telephone television or data transmission commutation cellthe elementary switching device in a power converter circuit it could be a transistor a thyristor a mercuryarc valve or others commutator electrica component of a dc electric machine that connects the rotating coils with an external circuit through brushes compact fluorescent lampa fluorescent lamp with a folded or spiral tube designed to fit in the same space as an incandescent lamp of similar light output compactrona brand of vacuum tube used in some radio and television sets that combined multiple independent functions in one envelope compensation windinga winding on a motor or generator to improve commutation at heavy load computed tomographyproduction of images of a crosssection through an object by multiple xray measurements processed in a computer computer engineeringthe profession of desiging computers computer hardwarethat part of a computer system with physical existence computer programmingthe practice of producing instructions for a computer to achieve some desired effect computeraided designa design discipline where a computer is used to produce graphical representation of the design or to assist in calculating performance parameters conduction bandin a conductor the energy levels of charge carriers that are free to move through the material constant k filtera method formerly used for designing filters for a required characteristic consumer electronicselectronic devices intended to be owned by consumers directly a mobile cell phone is consumer electronics but the cell site it communicates with is not contactoran automatically controlled electrical switch relay used to operate motors or other highcurrent loads continuous fourier transforma mathematical operation that expresses a signal in time as the sum of its frequency components continuous signala signal that can take any value within its range control engineeringthe application of control theory to practical problems control systemthe equipment used to adjust some parameter of an ongoing process to regulate its behavior to a desired goal such as positioning a disk drive head or regulating temperature of a furnace control theorythe mathematical study of behavior of control systems controllabilityin control theory the degree to which a system can be put into any desired state given manipulation of one variable controller control theorya system that adjusts some variable to control a process copper cable certificationthe process of testing a computer network cable installation to verify that it meets standards copper lossthat portion of an electric machine or transformers loss attributed to the resistance of conductors which are not necessarily made of copper corona ringa component of a high voltage system intended to smooth out the electric field distribution around energized parts coulombthe si unit of electric charge coulombs lawthe mathematical relation between force electric charge and distance cpucentral processing unit the element of a computer that carries out arithmetic and logic operations crest factorthe ratio of peak to effective rms value of a waveform crossedfield amplifiera type of microwave amplifier vacuum tube crosstalkobjectionable presence of a signal from one circuit in another circuit sharing the same transmission path such as a cable crystal oscillatoran electronic oscillator whose frequency is stabilized by a piezoelectric crystal resonator element uk converterone kind of buckboost voltage converter that uses a capacitor as an energy storage element current electricitythe movement of electric charge current densitythe current flowing per unit area of a conductor current source invertera type of power inverter where an inductor tends to keep a constant current flowing in the inverter stage current sourcein circuit theory an element that produces a defined current independent of the connected circuit properties current transformeran instrument transformer used for measuring current in ac power systems currenttovoltage convertera transducer that produces an output voltage in response to an input current cyberneticsthe science of automatic control systems cycloconvertera type of variable frequency power converter that does not first convert ac to dc contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links d damping ratio a parameter that indicates how rapidly oscillations in a system die out if ever darlington transistor an interconnection of two transistors to provide a gain that is the product of the individual gains data compression any technique that allows information to be transmitted more compactly than originally expressed for example codes data networks a network for interconnection of computers and peripherals dc injection braking a method of slowing an ac electric motor by passing direct current through its windings dctodc converter a circuit that takes power froma dc source and generates a different dc voltage degaussing the process of reducing the residual magnetic field in a metallic object such as a ship delay line a circuit component that introduces a delay in a signal deltawye transformer one type of connection of a threephase transformer demand factor the fraction of actual use of some quantity related to the maximum that could be used in a specified time demand response the ability of a generating station or grid to follow changes in load while maintaining voltage and frequency within acceptable limits demodulation the process of recovery of information sound video data from a modulated carrier describing function a method for analyzing nonlinear control systems detector radio a circuit that demodulates a radio signal to recover information diac a fourlayer semiconductor diode that has a predictable breakdown characteristic dielectric a material that does not allow free flow of electric current digital audio broadcasting transmission of sound by digital signals over radio digital circuit a circuit where all points on the signal path have only one of two states digital computers a computer made of digital circuits digital control a control system that processes signals in digital form digital filter a filter implemented as a digital circuit digital image processing manipulation of an image by a digital computer digital micromirror device an element of a kind of digital projector system digital protective relay a power system protection device that processes signals in digital form digital signal controller a type of microprocessor that combines a digital signal processor element with a more general purpose microcontroller digital signal processing the technique of modifying the properties of a signal that has been converted to digital form digital television transmission of images using digital techniques digitaltoanalog converter a device that produces a voltage or current that is proportional to a digital value sent to it diode bridge an interconnection of diodes to rectify alternating current to direct current diode a twoterminal passive circuit element with a preferred direction of current flow direct current electric current that flows in one direction only direct on line starter a kind of motor starter that does not reduce the voltage at the motor terminals direct torque control a method of estimating motor torque as part of a variable speed motor drive discrete cosine transform a mathematical technique for representing a sampled signal as a sum of cosine waves of different frequencies discrete fourier transform a mathematical technique for representing a sampled signal as a sum of sine and cosine waves of different frequencies discretetime signal a signal represented as a time series of samples taken at regular intervals displacement current the effect of a timevarying electric field which induces a magnetic field just as the motion of electrical charges does display device any device that displays data from an information system such as a watch readout or an automatic scoreboard dissipation the loss of energy in a system such as dielectric loss in a capacitor dissolved gas analysis a technique for fault detection in oilfilled transformers distributed control system a control system in which significant parts of the control process are decentralized distributed element model an analysis of an electric circuit where capacitance inductance and resistance are distributed along the circuit not concentrated in lumped components as in a transmission line distributed generation an electrical grid where multiple small sources contribute energy instead of relatively few large central generating stations distribution board a piece of electrical switchgear which distributes electric power to multiple branch circuits distribution transformer a power transformer usually used to change the utility distribution voltage to a lower voltage for use on the customer premises dolby a trademark for a noise reduction technique for analog sound recordings dot convention a system for marking terminals on instrument transformers to maintain correct polarity doubly fed electric machine an electric machine where both moving and stationary elements have external connections handling significant power downsampling a technique for reducing the number of signal samples processed by a digital system decimation dqo transformation a technique used to simplify mathematical analysis of polyphase electric circuits droop speed control a method of regulating generators so that multiple units share the load proportional to their ratings dual control theory a branch of control theory that deals with systems whose characteristics are initially unknown dual loop a method of supervising contacts and wiring in a security system so as to detect some faults or tampering dvd digital versatile disc a type of optical disc for distributing video recordings and data using an orangered laser dynamic braking a braking system that extracts energy from a moving system to bring it to rest a dynamic braking system generally is not used to hold a position of a stationary object dynamic demand electric power a technique for load management on an electrical grid based on frequency measurement dynamic programming a technique for optimization of the solution of a problem by combining solutions to smaller subproblems dynamic random access memory a type of semiconductor memory where data is stored as electric charges on capacitors the charges must be refreshed periodically or else they will leak away losing the stored data dynamo a directcurrent generator whose exciting field is provided by an electromagnet contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links e earth leakage circuit breaker a protective device that opens a circuit when stray voltage or current detected that would present a hazard of electric shock eddy current a current induced inside a conductor exposed to a changing magnetic field edge detection an image processing technique used to identify boundaries of objects edison effect the emission of an electric current from a hot wire edison did not realize hed discovered the fundamental mechanism of the vacuum tube thermionic emission electret a dielectric material that permanently retains an impressed electric field the dual to a magnet electric arc discharge of electric current through an open space between conductors may be produced intentionally as a source of intense light and heat or may be a result of an electrical fault electric charge the physical property of matter that causes it to experience a force when placed in an electromagnetic field electric circuit a closed path through which an electric current can flow electric current the motion of electric charges electric displacement field in maxwells equations a vector field due to electric charges electric distribution systems that portion of an electrical grid that connects customers to substations or the bulk transmission system electric field gradient the rate of change of electric field with respect to distance electric field a vector field that exerts a force on electric charges electric generator a machine that converts mechanical energy to electrical energy by moving conductors through magnetic fields electric motor a machine that produces mechanical energy from electrical energy by moving conductors through magnetic fields electric multiple unit use of more than one electric locomotive on a train electric potential a measure of the work required to move a unit electric charge in an electric field electric power conversion generally changing the form of electric power electric power distribution in an electric grid the network that brings power from a substation or bulk supply to individual customers electric power research institute a nonprofit organization that carries out research on behalf of the us electric power industry electric power transmission the bulk movement of electric power for many customers from a generating plant to a local distribution network usually at high voltage electric power the rate of transfer of electrical energy past a given point electric shock an injury caused to people or animals by electric current electrical cable a flexible conducting wire to carry electrical power or signals usually covered with an insulating material electrical code a set of regulations for the use of electricity they may vary from municipal to international in scope electrical conductivity a measure of a substances ability to pass an electric current electrical conductor an object that carries an electric current with little loss electrical contact a separable part of an electric device that carries current when touching another contact electrical discharge machining edm shaping of a work place by small sparks electrical element in circuit theory a node at which some electrical property is concentrated resistance etc electrical engineering the profession of applying electricity to practical problems electrical equipment apparatus for generation transmission or utilization of electric power electrical grid a geographically distributed system to connect source and users of electric power electrical impedance that property of a circuit that resists the passage of electric current usually in the context of alternating current electrical insulation paper a grade of paper used for insulation of transformers electrical machines capacitors and some cables electrical insulation a material that resists electrical current flow electrical load a consumer of electrical energy turning it into light heat mechanical power data or chemical changes electrical machine motors and generators apparatus that converts between electrical power and mechanical power electrical measurements that branch of metrology concerned with electrical quantities electrical network a network of electrical components and conductors electrical polarity identification of electrical terminals where current is flowing in the same direction relative to the device electrical steel any of several types of steel used for manufacturing the magnetic field components of machines and transformers electrical substation a facility connecting a distribution network to a transmission network usually with one or more transformers electrical technologist a specialist in applying electrical theory and technique to practical problems electrical wiring regulations the legal framework for electrical installations in buildings electrical wiring the installation of conductors fixtures and protection devices for a structure or vehicle electricity meter an instrument to measure the electrical energy used by a customer for revenue purposes electricity pylon a structure generally of wood or metal to support wires electricity the set of physical phenomena associated with electric charges electrification applying electric power to a process that was previously done by other meansor development of an electric power system in a region that previously had none electroactive polymers a polymer that significantly changes size or shape when exposed to an electric field electrocardiograph a record of the electrical activity of the heart electrochemical engineering the profession of application of electrochemistry to practical problems electrodes an electrical contact that connects some medium to an electric circuit such as in an electrochemical cell or a vacuum tube electrodiesel locomotive a railway locomotive with a diesel engine generator and electric driving motors that can be powered by the diesel engine or the track electrical supply electrodynamics the branch of physics that studies electrical charges and electrical currents electrolyte a liquid or solid medium that carries electric current in the form of ions electromagnet a magnet that generates a magnetic field from an electric current electromagnetic compatibility the control of unwanted electromagnetic interference electromagnetic field the field produced by moving electric charges and magnetic fields electromagnetic induction the production of current in a circuit by the change of magnetic field intersecting the circuit electromagnetic radiation radio waves light and other radiation that travels through space at the speed of light electromagnetic spectrum the range of frequencies of electromagnetic radiation electromagnetic wave equation a a secondorder partial differential equation that describes the propagation of electromagnetic waves through a medium or in a vacuum electromagnetism the science of electric fields magnetic fields currents chargesand forces electromechanical a system that has both an electrical component and a mechanical component such as a motor or a relay electromote an 1882 demonstration of a prototype electric trolley bus electromotive force a difference in electrical potential between two points such as produced by a battery or a generator electron microscope an instrument that provides highly magnified images by use of an electron beam electronic amplifier a device that increases the power of an electrical signal by electronic means electronic circuit a circuit using one or more electronic devices electronic component an active or passive element of an electronic circuit electronic control unit in an automobile an embedded electronic system that controls some aspect of a vehicle ignition transmission and so on electronic design automation a system in which a computer provides assistance to the designer of a device or system electronic engineering the profession of applying electronics to practical problems electronic filter a filter that alters some frequencyrelated characteristic of a signal electronics the study of the flow of electrons through a vacuum gases or semiconductors electronic speed control a device for regulating the speed of a motor electrophorus an instrument used to produce electrostatic charge through electrostatic induction electrostatic motor a motor that relies on the forces generated by electric fields instead of magnetic fields electrostatics the study of stationary electric charges and resulting forces embedded operating system the common operating environment that supports embedded software it may be a highly tailored version of a general purpose operating system or written soley for the purpose of embedded system operations embedded software a firmware component of a microprocessor controlled system embedded system a computer system that controls a device or system with no or a minimal user interface for example the ignition system in a car may have a microprocessor to control it enameled wire wire insulated with a thin flexible layer of enamel used for electrical windings energy demand management a system to adjust energy demand to reduce costs energy economics a branch of economics concerned with energy supply and demand energy efficient transformer a power transformer designed to have lower than average energy loss energy returned on energy invested a measure of how long an energy producing system takes to replace the energy it took to make it energy subsidies payments to a consumer or producer of electric energy that are used as incentives for production or consumption enginegenerator a combination of an internal combustion engine and a generator often used as a standby power plant eniac the first general purpose electronic digital computer epstein frame an apparatus used for testing of magnetic materials equalization audio adjustment of the frequency response of a system to improve its utility equalization communications adjustment of the frequency spectrum of a signal to cancel out the effect of the frequency response of a communication path equivalent circuit in circuit theory a simple combination of elements that behaves at its terminals like a more complex combination equivalent impedance transforms a mathematical method to determine values of an equivalent circuit error correction and detection techniques used to improve reliability of computer memory or communications channels by including extra information along with the desired data ethernet a standard for wired computer data networks exponential stability a system that settles to a steady state after a disturbance at a rate proportional to exponential time extended kalman filter a strategy for estimating an unknown value in a nonlinear system by combining multiple measurements contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links f faradthe si unit of capacitance faraday shielda solid conductive shield around a volume which blocks electromagnetic fields faradaylenz lawone of maxwells equations describing the relation between a changing magnetic field and production of an electromotive force faradays law of inductionthe relation between a changing magnetic field and the resulting voltage produced in a closed path fast fourier transforma digital algorithm to analyze a time series of sampled data into a set of sine and cosine frequency components fault power engineeringa short circuit open circuit or other disruption of a power system faxfacsimile the transmission of paper images by radio or by wire feed forward controla control system that adjusts the controlled variable based on a model of the process and measurements of disturbances instead of feedback from measurement of the process feedback amplifieran amplifier that feeds back a small sample of its output to its input to improve linearity feedbacka system that samples part of its output and adds that to its input feedback may be either positive or negative aiding or opposing the initial input signal feedin tariffa premium rate paid to distributed generators to encourage alternative energy sources ferrite corea magnetic core for an inductor made from a metal oxide compound ferroelectricitythe property of materials that spontaneously maintain an electrical polarization as a ferromagnetic material maintains magnetic polarization fiber optic cablea transmission medium that uses infrared energy or light to transmit information down a long thin transparent filament such as glass field effect transistora transistor that relies on modulation of conductivity of a channel instead of injection of minority carriers as does a bipolar transistor fieldoriented controla control strategy for variable frequency drives that models the magnetic field of the motor to control its torque filter signal processinga circuit that selectively alters a signal based on its frequency components filter capacitorin a power supply a capacitor that smooths the dc voltage produced by a rectifier stage finite impulse responsea class of digital filters whose response to an impulse returns to zero in finite time firmwaresoftware of a computer that is never or rarely altered during its working life for example the control computer program for an automotive ignition system fleming valvethe first important vacuum tube device used as a radio detector flemings lefthand rule for motorsa mnemonic to recall the relative orientation of current magnetic field and resulting force for electric motors flemings righthand rule for generatorsa mnemonic to recall the relative orientation of current magnetic field and resulting force for electric generators fluorescent lampa lamp that relies on a phosphor coating to produce visible light from the ultraviolet light generated by a mercury discharge flux linkagein a magnetic system that part of the magnetic flux that passes through a given closed path which may be a winding flyback convertera type of voltage converter that stores energy in an inductor flyback transformera type of transformer that recovers energy stored in its own core historically used in the deflection circuits of crt display systems forward convertera type of voltage converter that relies on transformer action to couple energy to its output circuit fossilfuel phaseouta plan to replace coal oil or natural gas fuel with other sources to produce electrical energy fossilfuel power stationa power plant using coal oil or natural gas fuel fourier seriesa set of coefficients of sine and cosine waves this can represent a time function as a function of frequency fourier transforman algorithm for converting a continuous waveform in the time domain into an equivalent set of spectral components in the frequency domain free space optical communicationstransfer of information from point to point by a beam of light or infrared energy instead of a wired connection or radio waves frequency changeran electric machine used to transfer power between two networks with different frequencies or an electronic device more usually called a frequency mixer that changes the frequency of an input signal to some other frequency frequency modulationa method of impressing information on a carrier wave by changing its frequency frequency responsethe measure of the output of a system in response to an input of varying frequency full load currentthe current drawn by a motor or other electrical machine at its full rated power and standard voltage fullwave rectifiera rectifier circuit that converts both positive and negative parts of the input alternating current waveform into a unidrectional direct current fuse electricala circuit protective device that interrupts excessive current by melting a metal strip fuzzy controla control system that relies on fuzzy logic instead of binary truefalse conditions contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links g gain scheduling a technique for control of nonlinear systems that use different control parameters based on some measurement of the process controlled galvanic corrosion electrochemical corrosion of one metal in contact with another galvanometer an instrument for detecting small electric currents gamma rayelectromagnetic radiation with wavelengths shorter than ten nanometres strictly radiation that is produced in the nucleus of atoms gasfilled tube an electron tube device that relies on the presence of gas for operation usually at less than atmospheric pressure gate turnoff thyristor gto a fourlayer power semiconductor device that can be turned on and off by signals at a control gate terminal gausss law a mathematical relation between the electric flux passing through a surface and the charge contained within that surface generator circuit theory in circuit theory an ideal voltage source or an ideal current source whose properties are independent of the connected circuit geothermal power extraction of energy from underground hot rock or natural steam sources gigabit one billion short scale bits a unit of digital data the project gutenberg plain ascii text of the king james bible is about 0034 gigabits global positioning system gps the us satellite navigation system declared fully operational in 1995 governor device a speed regulator for a machine such as a steam engine an early important feedback control cybernetic system grid energy storage any system tied to an electrical grid that stores electrical energy at low demand times and releases it to meet peak loads it might be a centralized station like a pumpedstorage hydroelectric plant or might be distributed over many customer sites such as by the use of electric vehicle batteries gridtie inverter a power inverter that allows synchronization with the electrical grid for export of energy surplus to the facilitys needs ground electricity a reference point for electrical potential often connected to the earth ground and neutral protective and circuit return conductors in a wiring system groundlevel power supply a system for providing powers for electric trams without overhead wires and without a permanently energized third rail growler electrical device a test instrument that is used to diagnose some faults with ac motors gsm the second generation of cellular mobile phone technology deployed since 1991 in europe gunn diode a twoterminal solidstate device that is used in microwave oscillators gyrotron a high power vacuum tube oscillator that can produce microwave frequencies up to hundreds of gigahertz at power levels up to megawatts contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links h h infinityan optimization strategy for certain classes of control problems hall effect sensora device that detects and measures magnetic field by the hall effect voltage induced in a currentcarrying semiconductor harmonic distortionan effect of a nonlinear signal path that introduces frequencies that are integer multiples of an input frequency harmonic oscillatoran oscillator which produces sinusoidal output such as a simple rlc oscillator harmonica waveform that has a frequency which is an integer multiple of another frequency harmonics electrical powerdistortion of the power line voltage due to nonlinear loads such as rectfiers hbridgean array of four controlled switches that coverts direct current to alternating current with peak value equal to the supply voltage hdtvhigh definition television any television system with more than 625 scan lines headphonean audio transducer or pair of transducers arranged to be worn on or in the ear heat transferthe study of the flow of heat energy heat transfer concerns dictate major design features of most electrical and electronic systems heatsinkin electronics a structure intended to dissipate heat from an active device into the ambient heaviside step functiona mathematical unit step function useful in the solution of certain differential equations by the methods of operational calculus helmholtz coilan arrangement of coils useful for producing a uniform magnetic field within a certain volume henry unitthe si unit of inductance hertzthe si unit of frequency equivalent to one cycle per second heterodynethe process of mixing signals of a number of frequencies to produce new frequencies heterostructurea semiconductor device built of two or more dissimilar materials hifihigh fidelity the set of techniques for reproduction of sounds that appear natural in source highvoltage cablea flexible insulated electrical conductor designed to withstand a significant voltage high voltage may be hundreds or hundreds of thousands of volts depending on the context high voltageany voltage at which safety concerns apply in some contexts anything over 100 volts may be a high voltage in electric power transmission voltages over 66000 volts are considered high voltage highpass filteran electrical network that tends to pass higher frequencies and block lower ones highvoltage direct currenta system for power transmission that uses high dc voltages for reasons of economy or stability highvoltage switchgearelectrical apparatus designed for control of highvoltage circuits hilbert transforma mathematical operation used in signal processing holographythe technique of representing the image of a scene by a recording of interference patterns of the light field home applianceany electrical appliance intended for use in a home homopolar generatora generator in which current and magnetic field direction are constant as the machien rotor revolves homopolar motora motor that produces torque from a current and magnetic field that does not change direction horsepowera unit of power equivalent to around 746 watts hot wire barrettera current dependent resistor formed of a fine wire in an envelope useful for regulating current humidistata switch that operates automatically on detecting a change in moisture content of the air hvachigh voltage alternating current depending on context this could be hundreds or hundreds of thousands of volts hvdc converter stationan element of a high voltage direct current power transmission system each end of the transmission line has a converter station connected to the local ac grid hvdchigh voltage direct current hybrid coila kind of transformer used for bidirectional transmission of signals over one pair of wires for example as in an analog telephone set hybrid electric vehiclean electric car with onboard engine for recharging or for assisting the electric drive motors hybrid synergy drivea brand name for a type of hybrid vehicle propulsion system hydroelectricityelectric power generated from falling water hydropowerpower now nearly always electric power generated from falling water hydroelectricity hysteresisa characteristic of a system where its state is historydependent contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links i igbtinsulated gate bipolar transistor a power semiconductor device that combines some of the advantages of fieldeffect and bipolar transistors image impedancea parameter used in design of electrical networks such as filters image noise reductionany technique used to reduce interfering effects in processing of an image image processingelectronic recording storage alteration and reproduction of pictures impulse responsethe response of a network to a sudden narrow pulse input incandescent light bulba device that uses a fine wire filament heated by an electric current to make lightand heat induction coilan early name for a transformer a type of transformer for highvoltage uses induction cookera cooking appliance that heats pots with magnetic fields induction generatora type of generator where the rotating field winding is excited by induction from the stationary armature winding induction motora type of motor where the rotating field winding is excited by induction from the stationary armature winding induction regulatora kind of variable transformer that provides stepless control of the output by changing the coupling between two coils inductive couplingtransfer of energy between two circuits through the magnetic field that passes through both inductive output tubea high power high frequency amplifier tube in some forms capable of megawatt pulses at hundreds of megahertz inductora circuit component with a concentrated inductance a coil stores energy in a magnetic field industrial and multiphase power plugs and socketselectrical fittings used to connect cables to threephase power circuits industrial automationthe general practice of automatic control applied to industrial operations infinite impulse responsea filter which mathematically never gets to a zero effect of an impulse at its input though practically the response may become negligible after a definite time information applianceconceptually an embedded computer system with a specialized user interface designed to simplify one task such as email or photos a modern smart phone approaches this concept information theorythe mathematical study of information informationin one sense the answers to uncertainties inputoutputthat part of a computer system devoted to exporting and importing data for example in humanreadable form inrush currentthe transient current that flows when first connecting a device to a power source institute of electrical and electronics engineers ieeethe american based society for electrotechnology institution of engineering and technologythe british society of electrical and electronics engineers instrumentation engineeringthe profession dealing with development of measuring systems instrumentationa device that turns some physical property into a measurement insulation monitoring devicea supervisory device to detect failure of electrical insulation insulator electricala substance that does not permit easy flow of electric current a fitting intended to support a conductor integrated circuitan interconnected array of electronic devices factory assembled on a single substrate intelligent controlthe application of artificial intelligence techniques to process control intelligent transportation systemthe application of information technology to manage some aspects of a transportation system intermittent energy sourcean energy source whose availability is not under human control it may be sporadically available or available on some natural schedule not coincident with human demands energy sources that are not dispatchable international electrotechnical commission iecan international standards organization devoted to electrical standards most countries are members international organization for standardizationan international organization coordinating the efforts of national technical standards organizations interrupterany of a series of automatically operated electromechanical switches that periodically opened and closed a circuit invertera system that converts direct current power to alternating current without the use of rotating machines using electron devices such as mercury arc valves or thyristors iron lossthat portion of the wasted power of a machine or transformer attributed to hysteresis and eddy currents in the iron core isolatedphase busa bus where each phase is in its own grounded metal enclosure to prevent faults from spreading from phase to phase often used in large power plant generators isolation transformera transformer especially intended to prevent leakage current from passing from its primary circuit to the secondary circuit iterative learning controla technique for improving the accuracy of control systems that carry out the same sequence repeatedly contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links j j operatorelectrical engineering uses j to represent the imaginary unit i to prevent confusion with the symbol for current j j 1 displaystyle jtimes j1 jedliks dynamoan early form of electric generator using electromagnets jfeta field effect transistor with a reversebiased pn junction between gate and channel joule heatingheating in a conductor due to passage of current joulethe si unit of work one joule is of the order of the energy dissipated when an apple falls off a table top k kalman filteran alrogithm for estimating an unknown value from a series of approximate measurements kelvinstokes theorema theorem in calculus useful in analytic solutions of problems in electromagnetism kilovoltamperea unit of apparent power kirchhoffs circuit lawsthe observation that the sum of currents at any node of a circuit must be zero and the sum of voltage differences around any loop must be zero often abbreviated kcl and kvl in lecture notes klystrona type of microwave oscillator vacuum tube contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links l lanlocal area network an interconnection of computers over a building or small campus laplace transforma mathematical operation for solution of differential equations by transforming them to the s domain from the time domain laser diodea semiconductor device that produces coherent laser radiation when properly energized leakage inductancethe inductance of a transformer that results from magnetic flux not linked by both primary and secondary windings lightemitting diodea semiconductor device that produces light or infrared or ultraviolet radiation when properly energized linear alternatoran electrical machine that generates electric power from the relative straight line motion of its parts linear motoran electrical machine that generates electric force in a straight line by the interaction of its moving parts and magnetic fields linear variable differential transformera transducer that produces an electrcial signal proportional to the movement between its parts lineman occupationa specialist technician who installs outside plant wiring overhead circuits power transmission lines litz wirea kind of stranded wire used to minimize losses in coils load flow studya mathematical prediction of the flow of electric power in a network based on a model of the actual or proposed system necessary for planning of electrical grids load following power planta power plant that can economically be operated over a significant range of output so as to meet varying electric power demand loadloss factora factor for estimating energy lost in a distribution network due to load current load managementany strategy for altering the operation of customer loads so as to reduce peak demand on an electrical grid load profilethe daily weekly or annual plot of electrical load against time local positioning systema navigation system that doesnt cover the whole earth such as over a coninent or even within a building lorana radio navigation system developed from a world war ii military system gee used for civilian purposes till the 1980s lorentz force lawthe mathematical relation between currents in conductors and the resulting magnetic forces between them lossless data compressionany data compression method where the source can be reconstructed exactly where approximations are tolerable lossy data compression can be used lossy data compressionany data compression method which allows only a close approximation of the source to be reconstructed useful for images or music where the human perceptual system compensates for the errors loudspeakera transducer that converts electrical current into sound perceptible to more than one listener lownoise amplifierin a satellite radio receiving system an amplifier placed near the antenna lownoise block downconverterin a satellite radio receiving system a device that amplifes and converts signlas to a lower frequency band that will have lower losses in interconnecting cables lowpass filteran electric filter network that passes lower frequencies and blocks higher ones lti system theorythe theory of systems that over a useful range respond proportionally to inputs and dont change characteristics while responding lumen unitthe si unit of luminous flux the energy of visible light lumped parametersdescribes an electrical network where the circuit elements are small compared to the wavelengths of the signals passing through it lyapunov stabilitya criterion for stability of a dynamical system if disturbances from a stable point reduce and the system returns to that stable point it can be said to be lyapunov stable contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links m machine learningthe set of artificial intelligence techniques for systems that can follow examples to solve new problems magnet wirethe class of wire manufactured for winding electromagnetic coils such as in motors or transformers magnetic blowouta component of a switching device that uses a magnetic field to assist in extinguishing the arc using a permanent magnet or a coil magnetic circuita path through which magnetic flux passes magnetic constantthe constant that relates the strength of magnetic flux to magnetic induction in free space magnetic core memorya type of computer memory that stores data as magnetization in tiny rings of ferrite material magnetic fielda field that causes magnets and currents to experience forces magnetic flux densitythe amount of magnetic field per unit area in si units measured in webers per square metre magnetic fluxthe magnetic field a conductor that encloses a changing magnetic flux will have a voltage induced in it magnetic momentthe proportionality constant that relates the twisting torque produced on an object to the magnetic field magnetismthe class of natural phenomena related to magnets and magnetic fields magnetizationa property of a material that measures its response to a magnetic field magnetization currentin a transformer that portion of the current used to support magnetic flux magnetostaticsthe study of stationary magnetic fields magnetostrictiona property of some materials that change shape when subject to a magnetic field magnifying transmittera concept for a signal transmitter that used a resonant transformer to provide a high voltage main distribution framein a telephone central office the equipment that connects to subscriber circuits mainframe computera large centralized computer system used for large volumes of data or supporting multiple interactive terminals with large inputoutput capacity generally expected to provide critical services to a business or institution with a predictable degree of reliability mains electricitycommercial electric power purchased from an offsite source shared by many consumers regional supplies vary in voltage frequency and technical standards mains huminterference on an audio or visual signal related to the power line frequency marginal stabilitysaid of a system that neither returns to its initial state when disturbed nor diverges to some unstable condition marine energyany technique for extracting useful energy from tides waves salinity or temperature gradients of the ocean marx generatora kind of circuit for generating very high dc voltage pulses masera device that produces microwave energy in a similar manner to a laser maximum prospective shortcircuit currentthe calculated value of current that could flow if a short circuit occurred a parameter for selection of circuit protection devices maxwells equationsthe fundamental relations between electric and magnetic fields expressed in concise mathematical form mechanical rectifieran electromechanical device for converting alternating current to direct current using sets of contacts which operate in synchronism with the ac mechatronicscombinations of mechanical systems with electronics for sensing and control memristora hypothetical nonlinear passive twoterminal electrical component relating electric charge and magnetic flux linkage mercuryarc rectifiera mercuryarc valve a vacuum tube device that converts alternating current to direct current by an arc in mercury vapor displaced by solid state devices but formerly much used especially in high voltage direct current transmission mercury vapor lampa lamp that generates light from a discharge struck in mercury vapor formerly widely used in outdoor lighting now replaced by lamps with better efficacy mesh analysisa strategy for solution of the voltage distribution in some types of electrical networks mesh networkinga topology where infrastructure nodes connect to other nodes such as to convey information metadynea dc electric machine with crossed fields and two sets of brushes used as an amplifier or rotary dc transformer metal rectifierrecifiers made from copper oxide or selenium formerly widely used before development of silicon rectifiers micro combined heat and powerequipment that generates process or space heat and electric power of a size useful for a single building microcontrollera microprocessor integrated with memory and inputoutput circuits useful for embedded control microelectromechanical systemsan electromechanical system of microscopic size they may be sensors or actuators microelectronicsthat part of the field of electronics dealing with integrated circuits microgenerationsmallscale electric power production to provide the needs of a small building or individual consumer microphonea transducer that changes sound into electrical signals microprocessora computer with its logical arithmetic and control functions implemented on one or a few integrated circuits microwave ovena heating appliance that uses microwave energy microwave radiothe subset of radio technique using wavelengths that are in the range of 3ghz or higher microwavepart of the radio spectrum with wavelengths shorter than 10centimetres millmans theorema theorem stating the relation between branch currents and voltages for multiple sources in parallel mineralinsulated copperclad cablecable with an outer metal cover and insulated by powdered inorganic material suitable for high temperature one kind of fire resistant cable mobile phonea handset that connects to the public switched telephone network by radio modbusa brand name for a serial protocol for industrial control equipment communication model predictive controla control strategy for process systems based on a mathematical model of the process and its disturbances modemmodulatordemodulator an interface between a computer system and a telephone network modulation transformerpart of a radio transmitter used to impress modulation on one amplifying stage modulationthe impression of information on a carrier wave for transmission monoscopea raster scan video device that generates a single fixed image for test or identification purposes moores lawthe observation that the number of transistors possible in an integrated circuit doubles approximately every two years morse codea method of transmitting text by long and short impulses and varying delays between them mosfetmetal oxide semiconductor field effect transistor a class of transistor using a single type of charge carrier and with a very thin insulating layer between current channel and control gate if you count those built into integrated circuits nearly all transistors are mosfets motion controlthat part of automation that deals with accurately controlling the movements of machines motor controllerelectrical apparatus that regulates and protects an electric motor which may be as simple as an onoff switch or a servo system for precision machine tools motor soft startera device that reduces the inrush current when an electric motor is first connected to the power supply mp3a standard for encoding audio in digital form mrimagnetic resonance imaging a technique for examining the interiors of for example medical patients using sensitive measurements of the magnetic fields of atomic nuclei multicsan influential early time sharing computer operating system first released in 1969 multimetera test instrument that can measure current voltage or resistance though not concurrently multisima brand of computer software for electronic circuit simulation contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links n nameplate capacitythe design power output of a generator at specified temperature rise nanoinvertergrid tied inverters rated less than 100 watts useful for connection of single solar pv panels to a building ac power system nanotechnologytechnology that uses devices whose principal dimensions are of the order of a few nanometres national electric codethe united states national technical standard for building wiring installation national electrical manufacturers association nemaa us trade association for electrical manufacturers that also develops technical standards negative feedbackfeedback from a control system output that tends to oppose the input negative resistancea voltagecurrent characteristic where increasing current leads to decreased voltage drop across the device negawatt powerin power grid demand management that portion of load that can be met by conservation efforts or improved energy efficiency neon signstrictly a sign that glows orange because of a discharge through neon gas less pedantically any gas discharge tube formed into a sign neonsign transformera highvoltage transformer with features intended to support operation of a neon sign net meteringa metering plan that allows grid customers with their own generation to be billed only for their net import of energy from the grid network analyzer ac poweran analog computer system for modelling power grids displaced now by digital computers network cablecables intended for use in data interconnections with defined performance parameters network protectora type of circuit breaker used to isolate a fault from a multitransformer supply network neural networksa network of individual logic elements in multiple layers that emulates some of the behavior of a biological nervous system a technique in artificial intelligence nodal analysisa technique for analysis of currents in an electrical network node circuitsa defined point in an electrical network with some potential relative to a reference node and where currents can be summed noise cancellinga type of microphone that preferentially picks up a near by sound source and rejects ambient noise noise reductionthe techniques used to reduce the perception of noise in a communications path nominal impedancethe rated impedance of an element of a circuit nonlinear controlthe class of control problems relating to the control of systems that are non linear nonodeany electron device although practically only vacuum tubes with nine internal active electrodes controlling electron flow nortons theorema theorem which states that any network of current sources voltage sources and resistors can be simplified to an equivalent network with only a current source and shunt admittance the dual of thevenins theorem notch filtera filter with a narrow reject band used to block for example a pilot tone out of a communications network ntscthe us national television systems committee that developed the analog monochrome and color television standards used for more than 60 years for broadcasting nuclear powerproduction of electric power or propulsion power by nuclear fission or fusion numerical controldigital automatic control especially of machine tools nuvistora type of miniature vacuum tube developed around the same time transistors became common in consumer electronics nyquist frequencythe maximum frequency that a sampling system can represent accurately nyquist stability criteriona graphical technique for evaluating stability of a feedback system nyquistshannon sampling theorema theorem that establishes the necessary rate to accurately sample a bandlimited signal contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links o observabilityin control theory the measure of how well the internal state of a system corresponds to its measurable outputs oerstedthe cgs unit of magnetic field h ohmthe si unit of electrical resistance ohmmeteran instrument that measures electrical resistance ohms lawthe mathematical relationship between voltage current and resistance oneline diagrama simplified schematic diagram of a power system onpremises wiringtelecommunications wiring owned by the customer opencircuit testa test of a transformer or other device with no load connected opencircuit voltagethe voltage developed at the terminals of a device with no load connected opencircuit time constant methoda method for approximately evaluating the transfer function of an electrical network operational amplifiera type of amplifier with differential inputs widely used in circuits where feedback determines the circuit properties optical fibera glass or plastic fiber used to convey signals transmitted by visible light or infrared radiation optimal controlthe branch of control theory studying optimization of a control system to fit some optimization criterion oscillationa periodic cyclical motion or disturbance oscilloscopean instrument for graphically displaying a waveform as a function of time oudin coilan early form of high voltage induction coil identical in principle to a tesla coil except for being constructed essentially as an autotransformer out of phasethe condition when ac generation sources are not synchronized overhead lineoutside plant run on poles or other structures power transmission or telecommunication wires oversamplingsampling a signal at a rate higher than required by the nyquist criterion overshoot signala transient excursion of a signal beyond its stead state value overvoltageapplication of more than rated voltage to a device oxygenfree coppera grade of copper preferred for electrical applications for its low electrical resistance contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links p padmount transformera kind of metal enclosed distribution transformer suitable for mounting on grade pantograph raila linkage that supports the current collector of an electric locomotive paraformera device similar to a transformer that couples energy between two circuits by varying magnetic parameters parameter estimationin estimation theory the practice of assigning values to a process model so it accurately predicts the processs behavior park transforma mathematical technique useful in the analysis of threephase systems partial dischargebreakdown of insulating gas or solid material by an electric field but without formation of an arc passivity engineeringincapable of adding energy to a signal or process patch cablesshort cables with connectors used to make connections between outlets of a patch panel or for temporary connections to a system under test peak demandthe maximum rate at which energy is consumed from an electrical grid may be either an instantaneous measure or the maximum energy transferred in some interval such as 15 minutes peltierseebeck effectthe thermoelectric effect movement of heat due to electric current flow pentagrid convertera type of self oscillating vacuum tube used a frequency mixer in superheterodyne receivers pentodeany fiveelectrode electron device but usually a kind of vacuum tube permanent magnet synchronous generatoran ac generator that uses a permanent field magnet instead of an electromagnet permanent magneta magnet that retains its polarization after an external field is removed permeability electromagnetismthe amount of magnetisation in a material resulting from an applied magnetic field personal computera computer cheap enough to be useful to a single person personal digital assistanta pocket size device that combines an electronic notepad with calendar and other functions something like a modern smart phone but without the ability to make phone calls phase converterelectrical apparatus that converts power from a system of phases to another system for example converting singlephase power to threephase phasefired controllersan ac power controller that adjusts the effective value of output by switching on at a variable time phase in the ac cycle phase locked loopan oscillator circuit that produces an output signal that is in a fixed timing relation to a reference input phase modulationimpressing information on a carrier wave by advancing or delaying the waveform slightly related to frequency modulation phasor electronicsa vector representing a signal of a given frequency in phase space phasor measurement unita system that measures the timing and amplitude of voltages and currents on an electrical grid synchronized over a wide geographic area the resulting measurements can be used to manage power flow on the grid phonographa record player a device that converts the mechanical movements of a stylus in a disk or cylinder recording groove into sound photocella light sensor that produces or alters a voltage when light is present photodetectorany device that detects visible light photodiodea twoterminal device whose terminal voltage or current changes in response to light photometeran instrument that measures light photonicsthe technology of conveying information through light or infrared radiation photoresistora resistor whose resistance varies when light strikes it phototransistora transistor sensitive to light pid controllera process control system that has proportional integral and derivative terms in its response to errors between measured value and setpoint piezoelectric effectproduction of a voltage in response to mechanical pressure or mechanical deformation piezoelectric motora type of motor that uses piezoelectric elements to generate force pin diodea multilayer semiconductor diode with a thin region of intrinsic material between its pdoped and ndoped regions planar graphin network theory a set of nodes and interconnecting lines that can be given in one plane without crossing lines plasma physicsa state of matter where electric charges are free to move plenum cablea fireresistant data communications cable that is permitted to be installed in the air handling spaces of a modern building plugin hybrida hybrid electric vehicle that can be recharged from grid power as well as its own enginegenerator pn junctionthe boundary between two differently doped regions of a semiconductor polarization densitya measure of the increase of the intensity of an electric field over that in free space owing to the separation of atomicscale electric dipoles polyphase coila coil intended for connection to a polyphase power supply polyphase systeman alternating current power transmission system using three or more wires each of which carries a current that is displaced in time with respect to the others pontryagins minimum principlea mathematical principle used in the theory of optimal control port circuit theoryany place at which energy can be observed to enter or leave a system positive feedbackfeedback from the output of a system that tends to increase the effect of any input if overdone leads to instability potential differencevoltage difference the amount of work required to bring a test charge from one point to another divided by charge magnitude potentiometera three terminal variable resistor which can be configured as an adjustable voltage divider power bjta bipolar junction transistor that can be used in circuits handling a watt or more of power power cableflexible insulated electrical conductors used to transmit electric power power conditionerany system intended to alter some property of the bulk power supply to improve it for some application such as filters surge suppressors voltage regulators uninterruptible power supplies and many others power consumptionthe rate at which a device consumes energy power converterapparatus intended to convert electric power to another form of electric power such as conversion between ac and dc or changing frequency or phase number power distributionthat portion of an electrical grid between the substation or bulk supply and the end consumer power electronicsthe class of electronic devices handling power greater than a watt power engineeringthat part of electrical engineering that deals with the generation distribution and consumption of electrical power powerfactor correctionapparatus intended to bring the power factor of some load closer to 1 power factorthe ratio of apparent power flowing to a load divided by the real power powerflow studya load flow study mathematical prediction of the magnitudes and direction of power flow in an existing or planned power grid an essential part of grid management power generationthe practice of converting other energy sources to electric power power gridan interconnected network of generators transmission lines and apparatus for reliable and economic transmission and utilization of electric power power invertera dc to ac power converter powerline communicationthe impression of carrier waves on a power line circuit for signalling purposes power mosfeta metal oxide semiconductor field effect transistor suitable for use in circuits handling more than a watt of power power planta facility that converts other energy forms into electric power power ratingthe nominal power that an apparatus or machine can handle with specified or customary temperature rise and life expectancy power qualityconformance of an electrical power supply with its specifications power storagea facility that changes electric power into some form that can be stored and usefully reconverted back to electric power for example pumped storage or battery systems power supplya subsystem of a computer or other electronic device that turns electric power from a wall plug or batteries into a form suitable for use by the system powersystem automationthe implementation of poweroperated switching and control that allows automatic operation of power system elements instead of manual operation powersystem protectionthe technology of limiting the spread of failures of a power system to a minimum and of preventing permanent damage to apparatus or conductors by such faults printed circuit boardan etched wiring assembly for interconnection of electronic components printer computinga device that makes permanent human readable images and text from computer data process controlthe field of study of automatic control of processes programmable logic controllera computer system designed to be rugged enough for industrial use and with a programming environment highly tuned to the domain of industrial control problems programming languagea formalism for humanreadable instructions to a computer protective relayan electromechanical or electronic device that detects faults on a power system and can signal circuit breakers to operate proximity effect electromagnetismthe increase in circuit resistance when the magnetic fields of multiple ac currents interact pulse transformera transformer designed to create or transmit pulses pulsewidth modulationtransmission of information by varying the duration of pulsesor varying the average output voltage of a power converter by varying the duration of pulses pulseamplitude modulation pamtransmission of information by varying the magnitude of a stream of pulses of fixed frequency pulsecode modulationany system for conveying analog information by altering some property of a stream of pulses pumpedstorage hydroelectricitya grid energy storage system that pumps water uphill for later use by a hydroelectric generator plant push switcha device that closes or opens an electrical circuit when pushed pushpull convertera converter with two sets of primary switching elements so that the transformer primary voltage can be reversed on each cycle contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links q quadrature boostera phase shifting transformer that can inject voltages that are time delayed with respect to the input voltage quality factorin a resonant circuit the ratio of stored energy to energy dissipated on each cycle of oscillation quantizationanalog to digital conversion changing a continuously varying analog signal to discrete digital numbers r radar cross sectionthe effective reflecting area of a radar target which varies with frequency geometry and surface composition radarradio detection and ranging the techniques for observing the speed and position of objects by reflected radio waves radio frequencyelectromagnetic waves with frequencies less than that of infrared radiation commercially important radio frequencies range from tens of kilohertz up to around a terahertz radio transmitterapparatus designed to generate radio frequency electric current which connected to an antenna can radiate energy through space radiothe technology of radio frequency devices railway electrification systema set of standardized methods for applying electric power in railway traction rankine cyclea thermodyanmic cycle an idealized version of the operation cycle of a steam turbine reactive powerthat component of apparent power flow due to the return to the source of energy stored in a loads electric or magnetic fields that does no useful work at the load realtime operating systema computer operating system that ensures responses with a bounded time to events such as in a controlled process receiver radiothe apparatus that takes radiofrequency currents induced in an antenna and turns them into useful signals rechargeable batterya secondary battery a battery that can have a useful portion of its capacity restored by connection to a supply of electric current reciprocity electromagnetisman observation that electric currents and electric fields can be analyzed from either point of view as regards the source of the energy in the system for example in radio a good transmitting antenna is generally also a good receiving antenna record playera phonograph a device that turns the variations in a disk or cylinder recording groove into sound rectifiera device that converts alternating current which periodically reverses to direct current that flows in only one direction may be a solidstate vacuum tube or electromechanical device rectiformera combination of a transformer and a rectifier used in electrochemical processes or supply of electrostatic precipitators recursive least squares filteran algorithm for a digital filter system reed switchan electrical switch made of two thin strips of ferromagnetic metal which touch when subject to a magnetic field regenerative brakinga braking scheme that returns energy to the source regenerative circuita circuit that employs positive feedback can be an amplifier or an oscillator relaxation oscillatoran oscillator that relies on an active device periodically changing state such oscillators usually produce a squarewave or sawtooth waveform different from the approximately sinusoidal waveshape of a harmonic oscillator relayan electrically operated switch reluctance motora type of electric motor that induces nonpermanent magnetic poles on the ferromagnetic rotor relying on varying magnetic reluctance the rotor carries no windings remanencethat portion of the applied magnetic field that the material retains when the external field is removed remote racking systema system for inserting circuit breakers into switchgear that allows the operator to stay at a safe distance from any possible arc hazard remote sensingacquisition of measurements of an object without contact for example measuring soil moisture by radar from an aircraft renewable electricityelectric power derived from primary energy sources that replenish on a rapid scale or that are not appreciably diminished by human exploitation renewable energy paymentsany incentive program to improve the economic return of a renewable energy project renewable energy policygovernment plans to displace fossil fuels with renewable sources repeating coilan old name for a transformer especially used in telephone circuits repoweringrefurbishing the equipment of a power plant with a view to improved efficiency or life span repulsion motora wound rotor induction motor using a pair of shortcircuited brushes on a commutator resettable fusea circuit protective device that opens on excess current and then on cooling off restores the circuit automatically residual current circuit breakera circuit breaker that detects unbalance of phase currents due to ground fault resistive circuita circuit containing resistive elements only no capacitors or inductors resistivitythe property of a material that impedes current flow resistora circuit component that primarily has resistance resolver electricala transformerlike rotary transducer that measures rotation as an analog value resonant cavityan opening that when excited by an electron stream or other means oscillates at a particular frequency resonant inductive couplinga form of energy transfer between two physically close tuned circuits rf connectoran electrical fitting used to connect cables carrying radio frequency currents rf engineeringthe profession that deals with application of radio frequency energy to useful ends rheoscopeobsolete name for an ammeter now an instrument for measuring fluid viscosity rheostatobsolete name for a two terminal variable resistor usually with a rotating shaft to allow manual or motor driven adjustment righthand rulea mnemonic device for remembering the definitions of the directions of current and magnetic field in generators ripple electricala periodic variation in the amplitude of a dc signal such as found in a power supply with partly effective filtering rlc circuita circuit that has only resistors inductors and capacitors in it roboticsthe field of automation that deals with manipulators especially those that mimic human appendages robust controla static control algorithm that can produce acceptable performance over an anticipated useful range of process disturbances rogowski coila current sensing coil that produces a voltage proportional to the rate of change of current by integration this can be turned into a measure of current root locusa graphical method for analyzing the properties of a transfer function as some paramter is varied root mean squarethe root mean square value of a waveform is the dc value that corresponds to equivalent heating value rotary converteran electric machine that converts electric power between two forms say ac and dc or singlephase and three phase or between two different frequencies of ac the latter two can be performed by the same machine rotary encodera transducer that converts rotation of a shaft to a measurement rotary switcha switch operated manually or electrically with a rotary motion of the contacts rotary transformera transformer used to couple electric signals or power between rotating parts rotary variable differential transformera transformerlike transducer that measures rotation as an analog value rotor electricthat part of an electrical machine that rotates not necessarily the armature routhhurwitz stability criteriona criterion for predicting the stability of a system with a given transfer function contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links s sallenkey filtera family of active filters with a secondorder characteristic first described in 1955 sample and holda circuit that takes a sample of a changing analog value and holds onto it until the value can be processed by some other stage sampling information theorythe process of taking a continually varying signal and turning it into a stream of numbers taken at regular intervals sampling frequencythe rate at which an analog value is sampled satellite radioa radio broadcasting service using signals from an earth satellite to customer receivers satellitea natural or artificial object that circles another bound only by gravity saturation magneticthat point in the magnetization of a substance where most magnetic domains are aligned with the external field further increase of the magnetizing force h gives only small increase in the magnetization b scadasupervisory control and data acquisition management of geographically distributed automation systems such as for an electrical grid schmitt triggera circuit that behaves like a snapaction switch suddenly changing state as an analog signal increases displays hysteresis schottky diodea diode that relies on the junction between a semiconductor and a metal scottt transformera transformer connection for balanced interconnection of a twophase system and a threephase system sdomaina laplace transform converts a function from the time domain to the complex frequency sdomain making certain mathematical operations much simpler to evaluate sdtvstandard definition television what descriptions of hdtv call any system with 625 scan lines or less segmentation image processinga step in digital image processing that groups picture elements of an image that notionally represent some physically significant property of the imaged objects selenium rectifiersone type of metal rectifier though selenium is considered a metalloid formerly much used but now replaced by silicon semiconductors semiconductor devicea device that relies on substances with electrical conductivity between that of insulators and conductors the controllable conductivity of these materials makes most of modern electronics possible semiconductor fabricationthe process of turning the raw source of silicon into transistors and integrated circuits semiconductora substance with electrical conductivity between that of insulators and conductors displays a negative temperature coefficient of resistance and is also sensitive to light the conductivity of semiconductors can radily be altered by trace amounts of other substances leading to devices that are the foundation of nearly all modern electronics sensora device or system that converts some physical event into an electronic signal for further use in measurement or control serial communicationtransmission of data as a single series of bits over a communication path series and parallel circuitselectrical circuits where current passes through multiple elements either one after the other or side by side like the rungs of a ladder or both shadedpole motoran alternating current single phase motor that produces a rotating magnetic field by a turn of wire around part of a field pole shaft voltagean objectionable stray voltage that appears on the rotating part of an electrical machine very deleterious to supporting bearings shielded twisted pairtwo wires wrapped around each other and covered with a flexible shield conductor intended to reject external interference shortcircuit testa test of machines or apparatus where the load terminals are directly connected usually done at reduced power to prevent damage but destructive short circuit testing may be carried out on circuit protective devices short circuita path in a circuit that has negligible resistance often unintended a fault shunt electricala small value resistor connected around a metering element to carry most of the current only a small part passes through the meter siemens unita reciprocal ohm the si unit of conductance the former siemens mercury unit was a unit of resistance signalsome intentional modification of a physical communication path that is intended to convey information from one place to another signal processingthe technology to extract information from signals signal strengtha measure of the usable power of a physical signal signalflow grapha formal mathematical treatment of the representation of signal flow through a system such as an analog computer or a radio receiver signaltonoise ratioa measure of the power contained in the useful part of the signal to the power contained in noise often measured in decibels for example in sound reproduction a 40 or 50 decibel signal to noise ratio would be broadcast quality whereas a 10 decibel ratio would represent very difficult operating conditions for a voice radio system silicon controlled rectifiera four layer semiconductor switching device that can stand off an applied voltage until triggered by an electrical pulse on a control lead silicon valleyinitially a region of california known for a large number of electronics technology firms sine wavethe waveform of the mathematical sine function a fundamental wave shape free of harmonics singlephase electric poweralternating current power system using only two wires where peak voltages in each wire occur at the same time singlesideband modulationa radio carrier modulation system where redundant frequencies of one duplicate side band are filtered out along with the carrier to save transmitter power skin effectthe tendency of alternating current to flow at the periphery of a conductor significant for large conductors at power frequencies and increasingly significant as the frequency increases sliding mode controla control strategy for a nonlinear system that uses discontinuous control signals slip ringa sliding continuous electrical contact between a machines rotating parts and the fixed external circuit small signal modelan analytical tool for systems that show significant nonlinearity for large signal excursions smart gridthe application of information technology to improve performance of the electrical grid smith charta graphical tool for display of the impedance of devices at varying frequencies and for solution of problems of impedance matching in radio frequency design software engineeringthe profession of designing software systems to meet specified performance requirements softwarethe set of instructions and data that direct a computer system solar cella photovoltaic cell used to produce power from sunlight solar energyuseful energy extracted by some means from sunlight solar microinverteran inverter suitable for use with a single solar panel solderingthe process of joining metals using a low melting point filler metal a critical process in the assembly of most electronic devices solenoida coil of wire used to create a magnetic field often a device with a ferromagnetic plunger that moves when the coil is energized solid state electronicselectronics that relies on current flow through crystalline lattices solid state physicsthat branch of physics that studies arrangements of atoms in fixed arrays sound recordingthe technology of recording sound for later reporduction space vector modulationa control strategy for variable frequency motor drives spark spreadthe difference between the revenue from selling a unit of electricity and the cost of the fuel used to make it sparkgap transmittera former type of radio transmitter that generated radio frequency current by exciting resonance of a tuned system with an electric spark used almost entirely for transmission of morse code spectrum analyzeran instrument that graphically displays the amplitude of signals in a narrow bandwidth across a frequency band speech processingthe techniques for improving the intelligibility of human speech in a communications system spicea set of computer programs for modelling the behavior of electronic circuits split phase distributiona type of distribution system that uses a center tapped transformer to provide two voltages to a building wiring system split phase motora type of single phase motor that uses a resistor inductor or capacitor and two windings to obtain a rotating magnetic field square wavea waveform that spends equal times at the positive and negative peak values with rapid transitions between them stability theorythe systematic study of control systems that deals with their response to disturbances stable polynomialthat class of polynomials representing the transfer functions of stable control systems stacking factora measure of the efficiency of filling the space of a machine core or winding the proportion of active material in any given unit cross section starmesh transforma mathematical technique used in circuit analysis state observerin control theory that which discovers and reports the internal state of a controlled system state space representationa mathematical technique to represent the internal state of a controlled system as a vector in a euclidean space static var compensatora system that adjusts reactive power flow without moving parts such as an electronically controlled capacitor bank statorthat part of a rotating electrical machine that remains stationary steadystatethe condition of a control system where changes due to some disturbance are no longer occurring at a significant rate steam turbinea rotating machine that converts the energy of expanding steam to mechanical power through its interactions with sets of moving and stationary blades step responsethe behavior of a control system in response to an abrupt change of input stepper motoran electric motor that moves its shafts in discrete steps as different poles are energized stereophonic soundsound reproduction systems intended to reproduce sound emanating from more than one direction stokes theorema theorem about integration of threedimensional functions much used in analysis of electric fields storage tubea type of cathode ray tube used for storing images or data stray capacitancea property of every conductor when considered as a nonideality structured cablinga system for design of the telephone and data communications cable systems of a building submarine communications cablea telephone or telegraph cable that is substantially under water sulfur hexafluoride circuit breakera kind of automatic circuit protection switch that breaks current in an atmosphere of pressurized sulfur hexafluoride gas to extinguish the arc super grida wide area power transmission network that allows interchange over continental distances supercomputera computer with a substantially higher level of performance than a general purpose machine especially adapted for high intensity calculation on large data sets superconducting electric machinean experimental type of generator or motor that has part of its electric circuits in the superconducting state superconductivitythe loss of all electrical resistance at inconveniently low temperatures superheterodyne receivera radio receiver that changes incoming frequencies to a fixed intermediate frequency for processing superposition theoremthe useful property of a system where the response to the sum is the sum of the responses surge arrestera device intended to absorb brief transient overvoltages to protect machines or apparatus surge protectionthe measures taken to protect machines and apparatus from transient overvoltages switchan electrical device that opens and closes a circuit it may be manually operated automatically operated by some other electrical circuit or operated by the change in some physical condition such as flow level or temperature switched reluctance motora motor that relies on induced magnetism in salient poles instead of a rotor winding switchedmode power supplya power converter that regulates voltage by adjusting the time duration of a switching device this gives reduced heat dissipation compared to an equivalent linear regulator device switchgearan array of switches circuit breakers and related apparatus for power distribution symbolic circuit analysisanalytical circuit analysis in terms of expressions with variables instead of numerical solutions for a particular case of values symmetrical componentsa technique to simplify analysis of unbalanced polyphase systems synchroa synchromotor a class of electrical motors that follows the rotation of a source synchronization alternating currentaligning the timing of two or more sources such as syncronizing a generator before connecting it to a grid synchronous circuita logic circuit where internal state changes only propagate in step with a master clock signal synchronous motora motor that rotates at a speed exactly related to the supply frequency synchronous rectificationa converter from alternating to direct current where switching devices actively are operated in step with the positive and negative excursions of the supply synchroscopean instrument used to bring an alternating current generator into synchronization with a grid that uses a moving pointer or set of lamps system identificationthe technique of development of a mathematical model of a controlled system model idenfitication system on a chipan integrated circuit that combines multiple significant subsytems of a product on one die for example analog signal processing and digital controls system on modulea packaging of significant functions of a complete product in a form that can be used in more than one product contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links t tachometeran instrument that measures rotational speed or angular velocity tap transformera connection to a winding at some point between the ends used to adjust voltage tap changera switch that selects which transformer tap is connected to an external circuit may be manually operated or power operated some types can be operated under load for voltage regulation purposes technical drawingdrawings intended to convey information for construction operation or maintenance of a system or equipment technologyapplied science telecommunicationthe field that deals with transmission of information over distances longer than can be covered by an unaided human telecommunications industry associationa us based trade association that develops technical standards telegrapha system for transmitting text messages by wire or other means telephone balance unita balun a transformer used to convert between balanced and unbalanced lines as used in telephone circuits telephone lineoutside plant that connects a central office to subscriber equipment telephonetransmission of voice by electrical means televisiontransmission of moving images by electrical means tellegens theorema theorem relating to branch currents in an electrical network tesla unitthe si unit of magnetic flux density tesla coila kind of resonant transformer capable of very high voltages almost identical to an oudin coil except that it has separately wound primary and secondary tetrodean electron device nearly always a vacuum tube with four internal active electrodes thermionic emissionemission of electrons from a hot surface the edison effect was an early instance of description of this phenomenon thermistora temperature sensitive resistor with a large somewhat variable temperature coefficient of resistance thermocouplea junction of two dissimilar metals that generates voltage when at a temperature above absolute zero thermoelectric effectthe conversion between heat flow and current flow and the reverse thermostata temperature sensing switch thvenin theorema theorem which states that any network of current sources voltage sources and resistors can be simplified to an equivalent network with only a voltage source and series impedance the dual of nortons theorem third railan energized conductor in the track bed using a sliding contact to transfer power to an elecric train threephase ac railway electrificationapplication of threephase power to railways threephase electric powerelectric power transmission using three conductors carrying currents which peak at separate evenly spaced times in each cycle widely used for motors thyristor drivea variable speed drive usually with direct current motors using thyristors as the switching elements thyristora four layer semiconductor device that stands off applied voltage until triggered tidal powerextraction of useful energy usually as electric power from the tidal rise and fall of water time sharinga system whereby multiple human users of a computer can proceed as if they had sole use while the computer processes each users software in roundrobin fashion timeinvariant systema systems whose characteristics dont vary significantly with time topology electrical circuitsthe shape of an electrical network independent of its size or values toroidal inductors and transformersmagnetic coils wound around a ring of ferromagnetic material total harmonic distortion thda measure of the magnitude of harmonicallyrelated frequency components a signal processing stage adds traction batterya battery used to store energy for propelling a wheeled electric vehicle traction currentpower supply for wheeled electric vehicles traction motoran electric motor for a wheeled vehicle traction substationa substation that supplies current to a railway subway or similar electric wheeled transit transatlantic communications cablea cable for voice or data running under the atlantic ocean transceiverapparatus that combines a receiver and transmitter transconductance transducersan instrument that converts a physical quantity into another physical quantity transfer functionthe mathematical relation between input and output usually expressed in terms of frequency or complex frequency sdomain transformer oil testingexamination of transformer oil for its insulating strength dissolved moisture and other properties to ensure it is still suitable for use transformer oila hydrocarbon liquid that cools and insulates transformers and other types of electrical apparatus transformera static arrangement of conductors and possibly magnetic materials that transfers energy by electromagnetic induction transformerboarda kind of insulating paperboard used for internal structures of large oil filled power transformers transient responsethe shorttime response of a system to a disturbance transila brand of transient voltage suppression diode transistora three terminal solid state device used as an amplifier or switch transmission telecommunicationsthe process of getting a signal from one point to another transmission linean arrangement of conductors for movement of electric power used from dc to upper radio frequencies transmission system operatora corporation that runs the transmission system between sources of power and distribution substations transmission towera structure for support of overhead transmission wires transmitterapparatus that prepares a signal for emission into some medium such as a radio transmitter or a sonar transmitter travelingwave tubea type of microwave amplifier vacuum tube trembler coila kind of high voltage coil that includes an interrupting mechanism formerly used in automobile ignition systems triaca variation of the thyristor that can pass bidrectional ac current triangle wavea waveform composed of straight line segments that extend from minus peak to plus peak trigger transformera transformer that generates a pulse to initiate some other device such as a thyristor or a flash tube triodean electron device nearly always a vacuum tube that has three active electrodes trolley polea support for a current collector on a vehicle trolleybusstrictly a passenger vehicle that collects motive electric power from a pair of overhead conductors tuned circuita circuit that displays a peak response at some frequency twisted pairtwo wires twisted around each other possibly covered with an overall sheath this configuration rejects some kinds of interference twophase electric poweran electtric power system using two sets of alternating currents displaced in time by a quarter period twoport networka network that has two places to exchange energy with its surroundings twosided laplace transforma variant of the laplace transform that simplifies certain operations contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links u ubiquitous computinga scenario where computer science is made to appear everywhere ultrasonic motora motor that relies on a component oscillating at an ultrasonic frequency ultrasonicsterm for the field of study pertaining to pressure oscillations in air or other media that are above the range of human hearing ultrasoundsound having a frequency above the range of normal human hearing a portmanteau of the former description of ultrasonic sound undersamplingsampling a signal at less than the nyquist rate can produce alias frequencies or other artifacts unijunction transistora three terminal semiconductor device with a definite switching characteristic and only one pn junction unipolar motora heteropolar motor all currents in this design flow in only one direction unixa computer operating system unshielded twisted pairtwo wires wrapped around each other but without a conductive cover upsamplingsampling at greater than the nyquist rate which makes filter design easier utility frequency60 or 50 cycles per second used for electric power utility polea columnar structure that carries wires for electrical power distribution cable television telephone or similar services contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links v vacuum capacitora capacitor using vacuum as its dielectric useful at high voltages or radio frequency vacuum tubean electron device that relies on flow of electrons through a vacuum or lowpressure gas a valve the first electronic devices that could amplify valvea switching element mercury arc thyristor or other device in a high voltage direct current converter each phase contains two or more valves which may be seriesconnected for higher voltages or a vacuum tube variable capacitora capacitor whose value can be changed by rotating a shaft squeezing a plate or by an electrical signal for example as used to tune a radio variablefrequency drivea power converter that varies the speed of an ac motor by changing its frequency usually today a solidstate device variacone brand of adjustable transformer that can essentially continuously vary the ratio between primary and secondary varicapvariable capacitor usually a diode whose reversebiased junction capacitance can be varied by applied voltage varistorvariable resistor a protective device that has a high resistance at low voltage but momentarily switches to lower resistance on exposure to a high voltage vector control motora strategy for control of variablespeed motor drives vector groupthe classification of the connections of a polyphase transformer vehicletogrida concept to use electric vehicle batteries as a form of grid energy storage vehicular automationautomatic systems to assist or replace the driver of a vehicle versoriuman antique version of an electroscope vibrator electronican electromechanical interrupter part of a dc to ac converter in a batteryoperated vacuum tube radio or similar application some had additional contacts to act as a synchronous rectifier video camera tubea family of vacuum tube devices used to pick up images and transmit them electronically video game consolean entertainment electronics device that allows one or more players to simulate such activities as ping pong or deadly combat usually can use a home tv set as a graphical display video processingthe techniques used to enhance video images virtual instrumentationa softwareintensive measuring system that can be programmed to emulate any of a number of conventional measuring instruments or some combination of measuring functions virtual power planta strategy for managing a collection of disparate power sources interconnected with a communications network as if they were a single centralized power plant vlsivery large scale integration the ability to put hundreds of thousands of interconnected transistors onto one chip voltthe si unit of electrical potential difference moving a charge of one coulomb through a potential of one volt transfers one joule of energy voltage compensationgenerally adjustment of a voltage source to compensate for voltage drop techniques differ widely between a computer power supply and a longdistance power line voltagecontrolled amplifieran amplifier that has its gain controlled by a voltage signal voltage controllera device that adjusts the effective voltage to a load voltage converterany device that changes electric power at one voltage to power at a second a transformer is a common example of an ac voltage converter voltage divisiona circuit that produces an output voltage that is some perhaps adjsutable fraction of the input voltage voltage doublera rectifier circuit that can product an output dc voltage of nearly twice the input ac voltage voltage regulationa measure of how a source maintains its output voltage for varying load voltage regulatora system that automatically stabilizes the voltage at which power is supplied to a downstream system voltage sourcein circuit theory a hypothetical element that maintains a specified voltage between its terminals independent of the current through it voltage spikea transient electrical voltage higher than normal appearing on an electrical supply voltagethe electric potential difference between two points voltagetocurrent convertera circuit that produces an output current proportional to an input voltage voltamperethe unit of apparent power in an ac circuit voltmeteran instrument for measuring potential difference contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links w war of currentsthe late 19th century commercial dispute on whether ac or dc was the best system for power distribution ward leonard controla speed control system for dc machines using an interconnected generator and motor wattthe si unit of power work done per unit time wattmeteran instrument that measures electrical power waveguidea tubular structure that guides electromagnetic waves much used at microwave frequencies an optical fiber is a kind of optical waveguide weberthe si unit of magnetic flux wet transformerin telephone systems a matching transformer that can operate while carrying a substantial dc wetting current wiener filtera class of filters used in signal processing used to fit an estimate to noisy signal data williams tubea cathode ray vacuum tube used as an early form of computer memory wind farman array of two or more wind turbines usually sharing a substation wind powergeneration of electricity sometimes mechanical power from wind wind turbinea rotating machine that extracts energy from wind wirea strand of metal much much longer than it is wide a conductor often coated with insulation wireless networkdata network relying on radio for the connection to end device may span a building or a larger area wireless telegraphytransmission of text by radio usually implies morse or radioteletype x xrayelectromagnetic radiation with wavelengths shorter than ten nanometres strictly radiation that is produced in the electron shell of atoms xray lithographya developing technique for production of very high density structures in integrated circuits y yagi antennaa type of radio antenna using a feeder element one or more parasitic reflector elements and one or more director parasitic elements to provide a directional characteristic the classic home tv rooftop antenna was usually a yagi antenna ydelta transforma mathematical technique in circuit analysis to simplify a circuit z z3 computeran electromechanical computer zener diodenickname for voltage regulator diodes which may rely either on the zener effect or avalanch breakdown to maintain a roughly constant voltage the two effects have opposite temperature coefficients of voltage zigzag transformera multiwinding three phase transformer sometimes used for grounding ztransforma mathematical operation that converts a set of evenly spaced measurements of an analog signal into a series of frequency components contents top 09 a b c d e f g h i j k l m n o p q r s t u v w x y z see also references external links glossary of engineering glossary of civil engineering glossary of mechanical engineering glossary of structural engineering national council of examiners for engineering and surveying fundamentals of engineering examination principles and practice of engineering examination graduate aptitude test in engineering vteengineeringcivil architectural construction environmental earthquake geotechnical hydraulic mining structural transportation mechanical acoustical aerospace automotive marine mechatronics railway thermal electrical computer control electromechanics electronics microwaves power radio frequency telecommunications chemical biochemical biological molecular petroleum process reaction thermodynamics transport phenomena interdisciplinary audio biomedical ceramics engineering mathematics engineering 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