INDAL Busbar DetailsDimension of Al. Bus barTotal Cross Section
Per Phase ( sq. mm)AC Current at an ambient of 35 deg & rise 50
deg.Correction FactorDerated current considering correction factor
as .667Width (mm)Thickness (mm)No. of barsNo. of bars0.667No. of
bars12341234123425.46.35161.29322.58483.87645.1635570597011000.667236.785470.235646.99733.738.16.35241.94483.87725.81967.745201020135015350.667346.84680.34900.451023.84550.86.35322.58645.16967.741290.326701290170519400.667446.89860.431137.2351293.9863.56.35403.23806.451209.681612.908101510200022600.667540.271007.1713341507.4276.26.35483.87967.741451.611935.489601740231026200.667640.321160.581540.771747.54101.66.35645.161290.321935.482580.6412352140280032000.667823.7451427.381867.62134.41276.35806.451612.902419.353225.8015052510324037000.6671003.8351674.172161.082467.9152.46.35967.741935.482903.223870.9617802860368042400.6671187.261907.622454.562828.0850.89.53484.12968.251452.371936.508301500197022600.667553.611000.51313.991507.4276.29.53726.191452.372178.562904.7411802050266030300.667787.061367.351774.222021.01101.69.53968.251936.502904.743872.9914952480315035600.667997.1651654.162101.052374.521279.531210.312420.623630.934841.2418602930366042000.6671240.621954.312441.222801.4152.49.531452.372904.744357.125809.4921203340408046800.6671414.042227.782721.363121.56203.29.531936.503872.995809.497745.9827504150490057400.6671834.252768.053268.33828.5876.212.7967.741935.482903.223870.9613552240283032400.667903.7851494.081887.612161.08101.612.71290.322580.643870.965161.2817402720336039000.6671160.581814.242241.122601.312712.71612.903225.804838.706451.6020803120390045500.6671387.362081.042601.33034.85152.412.71935.483870.965806.447741.9224203500440051000.6671614.142334.52934.83401.7203.212.72580.645161.287741.9210322.5630604450530061500.6672041.022968.153535.14102.0525412.73225.806451.609677.4012903.2036405000600068500.6672427.88333540024568.95Dimension
of each of droppersTotal Cross Section Per PhaseTotal Cross Section
Per PhaseTotal Cross Section Per PhaseTotal Cross Section Per
PhaseAC Current at an amb of 35
degWidthThickness25.46.350.000.000.000.0097038.16.350.000.000.000.00135050.86.350.000.000.000.00170563.56.350.000.000.000.00200076.26.350.000.000.000.002310101.66.350.000.000.000.0028001276.350.000.000.000.003240152.46.350.000.000.000.00368050.89.530.000.000.000.00197076.29.530.000.000.000.002660101.69.530.000.000.000.0031501279.530.000.000.000.003660152.49.530.000.000.000.004080203.29.530.000.000.000.00490076.212.70.000.000.000.002830101.612.70.000.000.000.00336012712.70.000.000.000.003900152.412.70.000.000.000.004400203.212.70.000.000.000.00530025412.70.000.000.000.006000Dimension
of each of droppersTotal Cross Section Per PhaseTotal Cross Section
Per PhaseTotal Cross Section Per PhaseTotal Cross Section Per
PhaseAC Current at an amb of 35
degWidthThickness25.46.350.000.000.000.00110038.16.350.000.000.000.00153550.86.350.000.000.000.00194063.56.350.000.000.000.00226076.26.350.000.000.000.002620101.66.350.000.000.000.0032001276.350.000.000.000.003700152.46.350.000.000.000.00424050.89.530.000.000.000.00226076.29.530.000.000.000.003030101.69.530.000.000.000.0035601279.530.000.000.000.004200152.49.530.000.000.000.004680203.29.530.000.000.000.00574076.212.70.000.000.000.003240101.612.70.000.000.000.00390012712.70.000.000.000.004550152.412.70.000.000.000.005100203.212.70.000.000.000.00615025412.70.000.000.000.006850
&C&"Arial,Bold"&14INDAL CHART
2x50x10CALCULATION OF ALUMINIUM dropper for 800APARAMETERSFeeder
Rating800ASize of Aluminium Bus Bar
considered2x50x10mm2i.e.Runs/Phase2mmCurrentWidth50mmThickness10mmfor
EIE-M grade (Amp)Current rating as per INDAL Aluminium (
E91)=0.97*EIE M grade current1455A1500Afor EIE gradeDesign Ambient
Temperature50oCRise in Temperature allowed40oCFinal Temperature
Permitted90oCSize of Bus Bar enclosure175 x
800sq.mmi.e.Height175mmDepth800mmFault current (for 1
sec)50000ADuration of Fault1sGrade of Al. dropperE91-EA.MINIMUM
CONDUCTOR SIZE Area of cross sectionFormula to determine the
minimum size of conductor for any fault level:t =(k/100) x (
Isc/A)2 x (1+ 20 . ) x t( Ref: Industrial Power Engineering and
Application Handbook, Page 865)t=temperature rise above operating
temp. in deg. C100oC(190-90)oC95oC(185-90)oCIsc=symmetrical fault
current in r.m.s in Amps.A=cross sectional area of conductor in
mm220=temperature coefficient of resistence at 20 deg C/deg
C0.00403for pure Aluminium0.00363for Aluminium alloy0.00393for pure
copper=operating temperature of the conductor at which the fault
occursk=1.166for aluminium0.52for coppert=duration of fault in
secondsAluminium starts softening at a temperature of around
180-200 deg.As a rule of thumb forAl conductor,on a fault a safe
temperature rise of 100 deg above the allowable end temperatureof
90 deg of the conductor during normal condition has been considered
& taken as the basisto determine the minimum size of the
conductorFinal temp. allowed for busbar after short circuit is 190
deg CBy putting all values in the above equation100 =(1.166/100) (
50000/A)2 (1+ 0.00363 x 90) x 1A=630.26sq.mmfor pure Al.( final
temp 190 i.e. 90+100)621.88sq.mmfor Al alloy( final temp 190 i.e.
90+100)646.63sq.mmfor pure Al.( final temp 185 i.e.
90+95)638.03sq.mmfor Al alloy( final temp 185 i.e. 90+95)B.THERMAL
RATINGI.DERATING FACTOR ON ACCOUNT OF HIGHER
AMBIENTTEMPERATUREDesign Ambient Temperature50oCOperating
temperature 90 deg COperating temperature 85 deg CRise in
Temperature allowed40oCAmbient tempPermissible Bar temp
riseDerating FactorAmbient tempPermissible Bar temp riseDerating
FactorDerating Factor k1 :0.88oCoCoCoC( Ref: Industrial Power
Engineering and Application Handbook, Page
870,871)35551.0530551.054050135501II.DERATING DUE TO
ENCLOSURE45450.94540450.94550400.8845400.88Cross sectional area of
busbar=No. of Phase x (Cross Section per Phase) x
10055350.81550350.815cross sectional area of enclosurecross
sectional area of
enclosure60300.7555300.75=300000=2.1428571429140000Derating Factor
due to enclosureAs per table 5(enclosed) of INDAL paper on INDAL
Al. Bus Bar,EnclosureRatioDerating Factorthe derating factor, k2
:0.75if ratio is less than 5%1.Outdoor