Reference documents: Copper Development Association

SWITCH BOARD REFERENCE : MAIN PCC - Busbar Rating - 1000 A

Busbar dimensions: Width = 50 mm Thickness = 12 mm X 1 RUN

1. Approximate DC Current Rating for Single Flat Bars (Apply Formula 4, Page 11 )

Formula 4 Page 11

I = current carrying capacity, A

A = Busbar cross section area, mm2.

p = Busbar perimeter of conductor in mm.

Hence,

Idc = 7.73x600^.5x124^0.39

= 1,241 A For Single Rectangular Section Bar

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 = (50*1000000/28733.33)

0.5 Where f - Frequenzy 50 Hz

= 42

Rf/Ro = 1.12 (from page 13, Fig. 7) [Skin effect Ratio]

(Rf/Ro)0.5 = (1.12)

0.5

= 1.0583

Hence,

Iac = 1240.76/1.058301

Iac = 1172 A For Single Rectangular Section Bar

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.

BUSBAR DIMENSION CALCULATION FOR 1000 A

As per Copper Development Association Hand Book, approximate current rating of busbar shall be carried out

by following methods.

I=7.73x A0.5

x p0.39