Busbar Correction factor for Temperature 1

[Ninja_Newyork]

Am designing a busbar system for my electrical application where the desired current rating is 4000A at 40 Deg amb. Am going with 2 runs of 100X10 CU busbar cross section, as per DIN 43671, the current rating for 2 runs in 2850A, if i multiply with the temperature correction factor for 100 deg is 1.45, then i can able to achieve the 4000A, but the question is do we have restrict the max busbar temperature to 90 deg.

 

[desertfox]

Hi
Are the busbars in an enclosure or out in the open air?
If the bars are in an enclosure I don’t believe that 2 bars of the section you are considering is sufficient enough for 4000A, I don’t have access to the din standards but I am looking at a book called copper or busbars by the copper development corporation which if you Google “copper for busbars” you can get access free online.
For a 4000A rating you need at least 3 bars according to my reference and yes if the ambient is 40 degrees C then the allowed tempErature rise is 50 degrees C Making a total of 90 degrees C the temperature limit.
Your references Might be different but without mOre information on your busbar arrangement I cannot comment further.

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[che12345]

Dear Mr. Ninja_Newyork (Mechanical)(OP)23 Dec 21 05:00
" ... I am designing a busbar system for ... current rating is 4000A at 40 Deg amb. Am going with 2 runs of 100X10 CU busbar cross section, as per DIN 43671, the current rating for 2 runs in 2850A, if i multiply with the temperature correction factor for 100 deg is 1.45, then i can able to achieve the 4000A, but the question is do we have restrict the max busbar temperature to 90 deg".
I do not understand German. Please check.
1. I think? the ratings listed in DIN 43671 is based on "ambient air still" i.e. bars in the (open air) [NOT in any enclosure]. Enclosed would lowered the rating, depending on the enclosure size and the IP rating.
2. Table shows 2//100x10 mm 2850A is with [painted] bars up to 60Hz. For [bare] bars is 2480A.
3. For ambient 40deg.C , bar temp 90deg.C ; factor = 1.33 approx. Factor =1.45 for 40-100degC.
4. If the bar are bare (Not tinned/silver-plated), limit the final temperature to 90degC is preferred. See also IEC 61439 .
5. Personal opinion: 2//100x10 mm would NOT carry 4kA at ambient 40degC. to bar temperature of 90/100degC. in an enclosure/enclosed in the switchboard.
Che Kuan Yau (Singapore)