Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
PRAVEEN PODDAR et al. ISSN (O): 2348-4098 ISSN (P): 2395-4752 Citation: 10.2348/ijset06150711 THERMALANALYSISOFSANDWICHBUSBARSYSTEM 1PRAVEENPODDAR,2Dr.K.S.SHASHISHEKAR 1PGStudentThermalpowerEngineering,SiddagangaInstituteofTechnology,Tumkur,Email: [email protected] 2Professor&AcademicDean,DepartmentofMechanicalEngineering,SiddagangaInstituteofTechnology,Tumkur,Email: [email protected] ABSTRACT A busbar is a strip or bar of copper, aluminum or any that conducts electricity within a switch board, distribution board, substation, battery bank or other electrical system. Its main purpose is to conduct electricity, not just to function as a structuralmember.Busbarsimprovessystematiccapacitance,lowerinductanceandimpedance. Commercially, the present practice is to use different busbars for different current ratings. The main reason for this is the variationintemperatureandtheentirebusbarsystemhastobereplaceddependingontherequiredcurrentrating.Thisisa timeconsumingandexpensivepractice.Topreventtheabovedifficultiesinthepresentworkabusbarwithfins,whichcanbe usedforvaryingcurrentratings,isproposed.Theproposalisdonebythermalanalysisofthebusbarandthetheoreticaland simulationresultsarecompared.ThereistheanalysisiscarriedoutbysimulationusingStarCCM+. Thetemperaturedistributionwithandwithoutfinsareevaluatedandnumberoffinisfixedfortherequiredheatdissipation ofthebusbar. Keywords:‐Busbar,Conductor,casing,Insulator,Fin, Method:‐Steadystateandunidirectionalmethod,StarCCM+. 1. INTRODUCTION A busbar in electrical power distribution refers to thick strips of copper or aluminum that conduct electricity within a switchboard, distribution board, substation, or other electrical systemor by another means busbar trunking system is a prefabricated electrical distribution system consisting of busbars in a protective enclosure, includingstraightlengths,fittings,devicesandaccessories The size of the busbar is important in determining the maximum amount of current that can be safely carried.Busbars are typically either flat strips or hollow tubes as these shapes allow heat to dissipate more efficientlyduetotheirhighsurfacetoarearatio.Abusbar mayeitherbesupportedoninsulators,orelseinsulation may completely surround it. Busbars are protected from accidental contact either by a metal enclosure or by elevation out of normal reach. Neutral busbars may also be insulated. Earth busbars are typically bolteddirectly ontoanymetalchassisoftheirenclosure.Busbarsmaybe enclosed in a metal housing, in the form of bus duct or busway, segregated‐phase bus, or isolated‐phase bus. Busbars maybe connectedto each other andto electrical apparatus by bolts or clamp connections. Often joints between high‐current bus sections have matching surfaces that are silver‐plated to reduce the contact resistance. The most common types of busbars present in the industry today are rigid busbars, strain busbars and insulated phase busbars. Each of these different types of busbars has different applications and uses. The rigid busbars are used in low, medium or high voltage applications, constructed with aluminum or copper bars and they make use of porcelain to insulate them. As for International Journal of Science, Engineering and Technology- www.ijset.in the strain busbars, they are mostly used in high voltage applications and are usually strung between the metal structures of a substation. They are held in place by suspension‐type insulators. Lastly, as for the insulated‐ phase busbars, they are used at medium voltage and similar to the rigid busbars, they are rigid bars that are supported by insulators. These busbars are able to eliminateshortcircuitsbetweenadjacentphases. Busbar trunking system is of two types: 1 Sandwich: Epoxy or Cast Resin type.2.Air Insulated: Fabricated Air Insulatedtype. As compared to air insulated busbar sandwich bus bar systems are widely used due to their economy, compactness,EnergyefficiencyandEconomical. Fig1SandwichBusbarSystem 711 PRAVEEN PODDAR et al. ISSN (O): 2348-4098 ISSN (P): 2395-4752 Citation: 10.2348/ijset06150711 2. METHODOLOGY Inthisworkmulticurrentratingbusbarsaredesignedby providing fins to dissipateexcess heatthat would restrict theuseofasinglebusbarformulticurrentrating. Conductionandconvectionmethodisusedtofindoutthe temperature of the busbar system casing by analytical methodandtheresultsareverifiedwithsimulation Calculation is carried out on vertical half portion of the busbar,asitissymmetricalongwithverticalaxis. Followingproceduresisfollowedfordesigningthebusbar system. a) Selection of Material:Aluminum alloys are corrosion resistant and comparatively easy to fabricate. The outstandingcharacteristicofaluminumisitslightweight, good thermal & electrical conduction and low cost comparedtocopper. Ti=346.36K 5)Implementingthefin The casing temperature obtained from the above calculation is not optimal temperature for easy installations. Hence, the optimal casing temperaturecan be obtained by introducing the convection fins on the casingoutersurfaces. b) Design Input:For designing the busbar, the data is collectedfromthestandardcatalogue. c)TheoreticalCalculationofBusbarsystem: Following parameters are considered for calculating temperaturesofthebusbarsystem. 1) Heat flow is assumed to be Steady state and unidirectional. 2)CalculationofHeatTransferinthebusbarby Q=I2*R Where Current(I)=2000ampand R‐ThermalResistanceoftheMaterialinW/k, ρ ∗ =2.20x10‐6 R Q=17.66W 3)CalculationofCasingTemperaturebyconvection Q=hxA(Tc‐T∞) Where Fig2:TypicalgeometryofBusbarSystemwithfin i)ToFindnumberoffins. Nooffins=Q/Qfin Qfin= and mfin= Where, P=perimeteroffin A=Areaoffin K=Thermalconductivityofaluminum h=freeconvection M (Ta‐Tc) h=Freeconvectiontake25W/m2k.(10or30W/m2k) A=Areainm2 Tc=CasingTemperatureink. T∞ =Initial(or)ambienttemperature(assumed30oc) Qfin=12.23W Nooffins=1.57(assumedtouppervalue)=2 Tc=337.12k ii)Tofindtemperaturedistributiononfin(Tx) 4) Calculating Total Heat Transfer inside the Casing is calculatedbyusingformula‐ Q=Td/RT Where Td=Temperaturedifference(Ti‐Tc) Ti–InsidetemperatureoftheBusbarsystem RT= Total thermal resistance & calculated by using formula RT=T/KA Where T=Thickness K=Thermalconductivity A=CrosssectionalArea International Journal of Science, Engineering and Technology- www.ijset.in ∞ Tx=331.62katthetipofthefins Theabovefindesignmethodologiesareusedtoobtainthe same fin tip temperature by assuming variable parametersare 1.Widthoffin,2.Thicknessoffin,3.Currentrating. d)Generating3DModel Using CatiaV5 CAD software is created the3d model for simulationpurpose. e)Busbarsystemsimulations: 712 PRAVEEN PODDAR et al. ISSN (O): 2348-4098 ISSN (P): 2395-4752 Citation: 10.2348/ijset06150711 AsthebusbarsystemissymmetricalongtheXandYaxes, the geometric simulation in Star CCM+ is carried out on quartersectiononly. Firstbyconsideringthebusbarsystemwithnofinsonthe surface by hiding the fins in the model and running the simulation.Thefinalresultofthebusbarsystemwithout finisasshowninthefigure3. Temperature inside the busbar is more as compared to outsidecasing.Thevaluesarementionedintheimages. Fig5:Graph‐TemperaturelocationpointsonFin 3. RESULTSANDDISCUSSION Correlationbetweentheoreticalandsimulationresults i) Busbarwithoutfin: Table1:ComparisonbetweenTheoreticalandsimulation resultswithoutfin Type Fig3:SimulationresultsofBusbarTemperaturewithout fin Similarly, the final results of the busbar with fins are simulatedbyunhidingthefinsinthemodelandsimulated. Thefinalresultswithfinsareshownbelow. Theoretical Simulation Difference results results in percentage inK inK Temperature on outside 337.12 casing Temperature insidecasing 346.36 339.62 343.83 +0.7% ‐0.7% ii)Busbarwithfin: Table 2: Comparison between theoretical and simulation resultswithfin Type Theoretical Simulation Difference results results in percentage inK inK Temperature on casing 331.62 outside 327.60 ‐1.2% 4. CONCLUSION Fig4:SimulationresultsofBusbarTemperaturewithfin Casing Temperature is verified by comparing the results betweenthebusbarwithfinandwithoutfin Temperaturedistributionsalongthelengthofthefinare obtainedat6locationsanditisplottedasshownbelow. International Journal of Science, Engineering and Technology- www.ijset.in Thepresentworkdealswiththedesignofamulticurrent rating Busbar, which can be commonly used in the electricalcircuitwithvaryingcurrentrating. In order to achieve the above objective, the common Busbarwithfinsisdesigned.Finsareusedtodissipatethe excess heat that would be generated when high current rating is used in the busbar. This design eliminates the 713 PRAVEEN PODDAR et al. Citation: 10.2348/ijset06150711 ISSN (O): 2348-4098 ISSN (P): 2395-4752 busbar change over delays and also the cost of the new Busbar. The analysis indicates that there is an observable reductionintheexcessivetemperaturebyintroducingthe finsonthecasing.Theresultsobtainedareinconcurrence withboththeoreticalandsimulationstudy. The maximum percentage of difference in temperature withfininthecoreis0.7%andthepercentagereduction incasingoutsidetemperaturewithfinis1.2%. REFERENCES 1. 2. 3. 4. 5. Robert T. Coney beer, W.Z. Black, R.A. Bush, IEEE TransactionsonPowerDelivery,Vol.9,No.4,October 1994 S.W.Kim,H.H.Kim,S.C.Hahn,IEEETransactionson magnetics,vol.38,no.2,march2002 Wu Anbo, Chen Degui, Senior Member, IEEE, Wang Jianhua,CaiBin,andGengYingsan Chang‐Chou Hwang, J.J. Chang, Y.H. Jiang, Electric PowerSystemsResearch45(1998)39–45. H.Hedia,F.Henrotte,B.Meys,P.DularandW.Legros. IEEETransactionsonmagnetics,VOL.35,NO.3,MAY 1999JOHNHUS. International Journal of Science, Engineering and Technology- www.ijset.in 714