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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
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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%.
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