3) Selection of Busbars

Selection of Busbars
Please take note of the following points before terminating busbars:

– The thinner the busbar the greater is the current loading because of its larger surface area for heat dissipation.


Fig:Copper bus bars


– Due to skin effect, the current in a busbar has auto tendency to flow along the outer skin and not in the central core.


Fig:Skin effect


– Due to proximity effect, the current distribution in a no. of parallel busbars is not uniform, more in the outer and less in the inner.


Fig:Proximity effect


So select busbars as wide as possible example are given below


Fig:Arrengment of busbars


– Vertical formation of busbars has larger current carrying capacity than horizontal ones because of better circulation of air and hence, cooling effect.


Fig:Vertical arrengment of busbars


Considering a rise over ambient of 50°C, the following guideline can be used for busbars. It is considered that the busbars are vertical, painted matt black




*symbol indicate Copper bus bar


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