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Current ratings of bars


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I was looking for a program to calculate the current rating

of various bus bars combination and sizes.  I have dowloaded  

your program busbar32.exe and examined the tab Busbar-Rating.  

Your program seems ok for single bars but to be usefull it  

should state the underlying assumptions such as frequency and  

maximum temperature  



I noticed that if you set the ambiant to 90deg C, you get a

rating of 0 for aluminum and a rating for copper. This seems  

to be wrong since aluminum rating would be approximately 62%  

(depending on conductivity) of the copper rating.


The reason you get the 0 rating for aluminium at 90 degrees and 0 for copper at 105 degrees is that the standards call for a maximum operating temperature for Aluminium of 90 degrees C and for copper of 105 degrees C. If the ambient temperature is equal to the maximum operating temperature, then the current must be zero. Any current would result in a temperature rise above the set limit.

Best regards

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