BUSBAR CALCULATION FOR CURRENT CARRYING

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BUSBAR DIMENSION CALCULATION FOR 1000 A
Reference documents: Copper Development Association
SWITCH BOARD REFERENCE : MAIN PCC - Busbar Rating - 1000 A
50 mm Thickness =
12 mm
X 1 RUN
Busbar dimensions: Width =
1. Approximate DC Current Rating for Single Flat Bars (Apply Formula 4, Page 11 )
As per Copper Development Association Hand Book, approximate current rating of busbar shall be carried out
by following methods.
I=7.73x A0.5x p0.39
I
A
p
Formula 4 Page 11
= current carrying capacity, A
= Busbar cross section area, mm2.
= Busbar perimeter of conductor in mm.
Hence,
Idc = 7.73x600^.5x124^0.39
For Single Rectangular Section Bar
= 1,241 A
2. Approximate AC current rating for Single flat bar 50 X 12 mm (Page 11, 13 & 37 )
Iac = Idc/(Rf/Ro)0.5
Ro1000 m = ∂20 * L/A
A
= cross section area, cm2
L
= 1000 m
∂20
= resistivity of copper at 20 °C, 1.724 µΩ cm (Page 11)
Ro1000 m = (1.724*100*1000)/(5.0*1.2)
= 28733.3 µΩ
Hence,
(f/Ro)0.5
Rf/Ro
(Rf/Ro)0.5
Where f - Frequenzy 50 Hz
= (50*1000000/28733.33)0.5
= 42
1.12 (from page 13, Fig. 7)
[Skin effect Ratio]
=
0.5
= (1.12)
1.0583
=
Hence,
Iac = 1240.76/1.058301
Iac =
For Single Rectangular Section Bar
1172 A
3. Approximate AC current rating for 1 No flat bars of 50 x 12 mm = 1172 A
CONCLUSION: FINAL CURRENT CARRYING CAPACITY OF THE ABOVE BUSBAR IS SUFFICIENT TO CARRY THE
REQUIRED BUSBAR RATING OF 1000 A.
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