Flexible copper busbar size

[Joaco M]

Hello everyone,

Im having some problems with a customer regarding the size of the flexible copper busbar we should put.

The nominal current That Will flow thourgh the busbars in normal condition will be 1600A

I suggested installing 100x1x10 flexible busbar

However he insists to install 63x1x10 flexible busbars. 630mm2 section seems tooooo small for me to carry 1600A and according to different vendors tables it looks small also

Whats your opinion or experience??

Thanks!!

 

[desertfox]

Hi

I completely agree with you, I looked on this site:-

https://flexiblebusbars.co.uk/current-ratings/

I would politely point out your concerns and ask him why he believes the flexible copper busbar he is requesting is suitable, bottom line is make sure it’s all in writing.

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

 

[Gr8blu]

Joaco: A usual safe bet is to size bus for max 1000 A/in2 (1.55 A/mm2). This covers the heating of the bus and the bolted connection capacity for other bus / lugged conductors. Thus for 1600 A I would think you need a minimum of 1000 mm2 in cross-sectional area - however you get there in terms of geometry. I would usually opt for a thickness of no less than 4 mm though, independent of whether I used braid or solid bus.

Converting energy to motion for more than half a century

 

[Joaco M]

Hi desertfox:

You say you agree with me but in the link you send it says that for 1600A is ok 63x1x10 flexible busbar.

What did you meant then ??

thanks!

 

[desertfox]

Hi Joaco M

There is no room for margin with the 600mm^2, it’s just about on the limit of the rating and that’s provided you have a 80mm wide terminal. I don’t know what other conditions make you choose the 1000mm^2 is it to do with temperature rise, short circuit current?









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

 

[che12345]

Dear Mr. Joaco M (Industrial)(OP)11 Jun 22 10:20
"...#1.Im having some problems with a customer regarding the size of the flexible copper busbar...The nominal current That Will flow through the busbars in normal condition will be 1600A. #2. I suggested installing 100x1x10 flexible busbar. However he insists to install 63x1x10 flexible busbars. 630mm2 section seems to small for me to carry 1600A and according to different vendors tables it looks small also.."
#1. The (current rating) of the flexible bus bar is significantly affected by: [ a) the ambient temperature that is surrounding the bar, b) the permissible temperature-rise and c) the holders and device around the bar]. For outdoor in cold countries/locations , the ambient may be taken to be lower than 40Deg C . The permissible temperature-rise may be 30, 40 or 50K. On the other hand, for some locations/connections the total temperature may be limited to 70Deg C instead of 105Deg C. See IEC 61439-1 for more detail..
#2. I am of the opinion that your proposal (100x1x10) would be a better choice than (63x1x10) insisted by your customer. Note: (100x1x10) is > (63x1x10). So, what is the problem, unless he is asking for some discount/lower the cost? Attention: get him to commit his (instruction) [in writing officially].
Che Kuan Yau (Singapore)

 

[cranky108]

Did you ask the customer why they wanted that? Did you lesson? Maybe he wanted that, because they have replacements for it, or they have specific tooling. Take that into consideration.

I have had the desire to fire consultants that kept suggesting items that I believed to be unworkable solutions.
I at least got them off the preferred list.

 

[7anoter4]

If it is low voltage supply system then a short-circuit current [rms] could be approx. 26 kA.[See IEC 60076-5]- Transformer of 1100 kVA 6% sc.voltage [400 V rated] for instance.
In IEC 60865-1 /1993 section. 2.3 it is a way how to calculate the dynamic effect in flexible conductor arrangement.
You may use also manufacturer literature for instance:

https://wiraelectrical.com/busbar-size-calculation-formula/

 

[LionelHutz]

We've found that 1000 A/in2 isn't a very safe bet if the area where it is installed isn't vented.