Urgent-Abt Busbar Sizing Calculation

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If a copper conductor conducts 4000 A at ambient temperature of 40 degree.and at 54 degree c.can i provide the same cross section of copper ? or am i want to go for higher rating?

Do your own homework!

Why any organisation would direct someone to size a busbar without also giving that individual access to the design manual with which to size it correctly, thereby prompting that individual to ask anonymous strangers in a global engineering internet forum as a matter of urgency, is a thing of great wonder and abstrusion.

Check this may help you

Busbar Sizing Calculation

Busbar cross section evaluation/calculation in two situations: short-circuit and continuous load. For short-circuit you have to state-at least-the clearing time.

For continuous load it depends on a few conditions as: natural or forced air circulation, the busbar geometry the enclosure shape and size. If the load will be

short time applied [or intermittent] will be another way to calculate it.

The maximum temperature it is dictated by the maximum temperature permitted for insulation-plastic, porcelain, silicon and so on.

As a rule of thumb the current for 54^oC ambient air with respect of 40^oC [let's say 85^oC will be maximum permitted] sqrt((85-54)/(85-40))*4000=3320 A.

if suppose the maximum permitted limit is 105 means the calculation changes rit?

Of course,the maximum permitted current will be then : sqrt((105-54)/(105-40))*4000=3543 A

As said already, busbar calculation simple formulas can only give rough results, which bring to a huge raw material overusage if we do not want to take risks.

Modern calculation softwares integrate conduction, convection, radiation, skin effect internal to one bar and induced by neighbouring phases, .... and allow to use up to half the cross section, with sophisticated shapes .. see http://www.youtube.com/watch?v=eHADHX-x85Y

have another doubt.our 1600 A busduct(720 mm copper flat ) is tested for 65 kA/1 Sec.i like to know how this 65 ka/sec is derived. please tell me the calculations