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Unformatted text preview: IEEE TRANSACTIONS ON ELECTRICAL INSULATION, VOL. EI-6,NO. 4, DECEMBER 1971 Computation of ElectricFieldDistributions in High-Voltage Equipment HUGH M. RYAN, MEMBER, IEEE,JOHN M. MATTINGLEY, AND MALCOLM F.SCOTT Abstract-In an earlier paper two of the authors described a general-purposedigitalcomputerprogram suitableforsolving,with considerableprecision,multidielectricfieldsintwodimensionsorin threedimensionswithatleastoneaxisofsymmetry.The program, after being rigorously checked, has been extensively used for severalyearstosolvemany practicalmultidielectricfieldproblems; onalloccasionsithasbeen completelysatisfactory. This paper, in addition to presenting supplementary program details, presents a few applications of the numerical method to high-voltageequipmentdesign. INTRODUCTION C< ONSIDERABLE interesthasrecentlybeenshown in developing numerical techniques for solving practical electric fields -. In a previous paper  a general-purpose digital computer program wasdescribedthatissuitableforsolvingpracticalmulti- dielectricfieldproblems intwo dimensions and inthree dimensions with one axis of symmetry. Forseveralyears,extensiveusehasbeenmade of this program in insulation design and development studies for bushings, circuit breakers and control equipment, transformers, and fields associated with high-voltage laboratory equipment. Further, with theaidofsupple- mentary digitalcomputerprograms,developedtofacili- tate detailed determination of potential gradients, this generalpurposeprogram hasbeenextremelyusefulwhen predictingbreakdownvoltagesingases,forgas-insulated equipment,and forawiderangeofelectrodeconfigura- tionsand test conditions,usingeithertheempirical ap- proach - orthesemiempirical method sug- gested byPedersen ,. Rigorousearlyvalidationstudieshave confirmedthat a highdegreeofprecisionisattainableforboth closed- and open-type multidielectric field systems; errors in computed potentialscan generallybe keptto lessthan 1percentinany regionofinterest. Certain practicalfieldsdonotpossess,norcan theybe assumed to possess, symmetry. Although such problems arenot yet amenable todirectsolutionusingthispro- gram,an approximatetwo-dimensional technique, shortly to be reported,based on Boag's simple approach , is oftenuseful. The presentpaper givesa fewtypicalexamplesthat demonstratethe applicationofthecomputerprogramto MantuscriptreceivedNovember 16,1970; revised June 7, 1971. The authors are with A. Reyrolle and Company, Ltd., Heb- burn,CountyDurham, England. practicalpowerfrequencymultidielectricfieldsamenable todirect solution. DIGITAL COMPUTER PROGRAM The general-purpose digital computer program de- scribed by Galloway etal.,  and outlined in Fig.1 hasbeendevelopedtosolvetheLaplace equationV24 = 0intwo dimensionsorinthreedimensionswithatleast one axisofsymmetry. A system ofrectangulargridsof unequal sizeisusedtosetup finitedifferenceequations for fields with multiple dielectrics and other required boundary conditions. Boundaries may be defined alongboundary conditions....
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This note was uploaded on 06/08/2011 for the course ELECTRICAL 124 taught by Professor Ghjk during the Spring '11 term at Institute of Technology.
- Spring '11