question

@MyHomeBuzz

I think it would be 1000A peak, not 1000A constant. (Edited from rms as it is incorrect refernce, as I was really referring to a sustained or constant current) I do see the logic and maths in the calculations.

But the question is sort of a moot point. There is not system that can connect to the few points to rms the amps on that bar.

1000x48v it a 48kva system. When building that big you will need alot more space and better current sharing anyway so would not use it? I personally would not use it on those systems as a better setup for current sharing and heat dissipation is needed.

At 12v 1000A thats a 12kva system. I don't know any 12kva at 12v? I could be corrected, would rather think it is an ultra daft setup anyway the poor batteries never mind the bus bar.

Hi @MyHomeBuzz,

A lot of limits in power electronics are related to heat, and the capacity of the adjacent materials to withstand it, and how it is dissipated, that would be an integral part of the rated capacity and one that is not accounted for in typically conservative generalised information.

There is an extreme amount of info related to the details in this document if someone was really wanting to investigate for themselves.

http://copperalliance.org.uk/uploads/2018/03/section-2-0-current-carrying-capacity-of-busbars.pdf

While perhaps not intellectually satisfying, the Lynx distribution system has been deployed in many thousands of systems, and I have never heard of anyone ever overloading the bars leading to an issue.

I have heard and seen people inadequately connecting to the bars, and that leading to issues at the point of connection, but never the bars themselves.

Unless there is some instance of the rated current (or even less than) leading to an issue with a system, I don't think I can get much more internal info than what is published in the long standing spec.

Propably wery interesting for a insurance company in case of fire and documentation?

When calculating the power loss of the lynx power in at 48V I get 0.0432V lost on the 2 29cm busbars, at full 1000A load that would be 43W of power lost (0.0009%). So as long as victron says that the enclosure can dissipate the 43W there shouldt be a problem

@Guy Stewart (Victron Community Manager)

Using 48V for your calculations is not realistic as you would probably find under a load of 1000A, voltage would be significantly lower and would effect heat dissipation. I also wondered about the "1000A" rating when I first opened the Lynx a long while back, thinking that the bus bars are undersized. If you derate your 1000A by 0.8 which would be a standard acceptable calculation when using DC @30C ambient inline with ABB or Schneider DC de-ratings you would find that your maximum rating for constant current would be @800A less additional derating with the correct factor as the ambient temperature increases. I hope no engineer would design and spec a circuit to load a 1000A on a product with 1000A rating. Minimum would be to design with the correct derating factor from the manufacturer. I would not design a circuit with more than 0.6 to 0.8 constant current of the max rated current at the specified temperature regardless of been asked to cut cost and push it the edge, especially using DC.

In summary In this scenario I would say that 0.8 derating @30C of the maximum current spec is a sensible idea, like I said I would probably be more inclined to consider ambient operation temperatures around the bus bar including being classed as "in an enclosure" and you would probably find that at 60C you would be sitting @600A at continuous current draw for any significant period of time. I think Victron are speccing their Lynx at the top end of what it can handle for a short period of time which is what most manufacturers will do. Maybe Victron should get their engineers to add some de-rating factors into the documentation to satisfy questions like this. But again going back to the engineering side of it, no engineer would design the circuit around 1000A anyway, atleast I would hope not. Just in the same way I see plenty of Multiplus and Quattros fitted closer than 100mm to trunking and other components when they shouldn't be. You will find most DC de-ratings are 0.8 @30C with quite a large decline in reducing the factoring for every 10 degrees C. Like I said I don't think 1000A is an unreasonable claim when backed up with the correct de-rating factors from Victron, which really they should publish to satisfy the consumer. You will probably find that if they listen to this post and publish the additional data I wouldn't be surprise to see it drop to 500-600A for continuous load in an enclosure in an engine room at 40-60C.

Stay safe,

MyHomeBuzz, you have asked an excellent question that has vexed me also. I too, am a huge Victron Fan, but (From an American point of view using American busbar ampacity formula and published tables) I cannot find any support for a 1000Amp rating. Much closer (as you pointed out) to 500-800 Amp, depending on temp, etc.) These ratings, do not take into account stainless steel studs (with MUCH lower conductivity) replacing bored out areas of the copper bar, thereby reducing the actual copper cross-sectional area at several points. I understand Guy Stewart's empirical deduction from "zero reported over-current melt-downs". However, the science does not support the claim.

One final curious point: The Lynx series busbars (as MyHomeBuzz pointed out) have a cross-sectional area of 240mm2 (0.3711 inch for us Americans) rated by Victron at 1000A. Yet, Blue Sea, and several other reputable manufacturers including Victron themselves (in their stand-alone 4-post and 8-post busbars) use TWICE that cross-sectional area of copper (0.75 inch) but rate these busbars at only 600 Amp DC continuous power (slightly less for AC current). Victron's own design engineers appear to disagree with one-another.on this point.