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Electrical contacting on aluminium busbar

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ConKbot:
I don't know if it gets used for bus bars or not, but Alodine or Iridite coatings can be used on aluminum for a conductive corrosion resistant surface. I've seen it used on surfaces that were for electrical shielding and grounding purposes, not as a bus-bar conductor so they may not be suitable. They are chromate conversion coatings, so hexavalent and trivalent chromium processes exist, with the former most definitely not being RoHS.

T3sl4co1l:
Two-ish questions:
1. Why is the brass or copper so easily bent?  Both are available in hardness grades; dead-soft would be annoying (gummy) to machine anyway.  Full hard is pretty springy.
1a. Why is the shop bending them at all?  Clearly they're a bad shop that can't follow directions (you did put a flatness spec on the drawing, right?..) and don't deserve your money, find another that will.
2. Why does it matter if it's slightly bent?  You have frequent mounting brackets to secure this long span of metal, right..? ;)

Regarding 2, it seems pretty common to use flat stock for bus bars, which will be even more flexible, which is fine because it's secured frequently, to account for flex, vibration and so on.

You may be just as well off using a more conventional approach -- #0 cable or thereabouts (or the metric equivalent, rather), with crimp lugs and bolted connections.  If you need a lot of drop connections, this isn't going to be very convenient, but it is just fine for a 1.3m length.

The other conventional approach would be a terminal block, then routing individual connections with thinner cable of lengths, say, 0.2 to 1.6m or whatever.  Instead of a multi-drop bus, you have a star connection.

Tim

damien22:

--- Quote ---Two-ish questions:
1. Why is the brass or copper so easily bent?  Both are available in hardness grades; dead-soft would be annoying (gummy) to machine anyway.  Full hard is pretty springy.
1a. Why is the shop bending them at all?  Clearly they're a bad shop that can't follow directions (you did put a flatness spec on the drawing, right?..) and don't deserve your money, find another that will.
2. Why does it matter if it's slightly bent?  You have frequent mounting brackets to secure this long span of metal, right..? ;)
--- End quote ---

I agree, but unfortunately have little control over that. Tried 2 suppliers and both same result with the second being slightly better. The problem is that it's down to the operator, and even if a set is good for a particular supplier, maybe next one won't be and that can go into production hell. We'll check for higher strength brass but I don't have much hope.

For the cable approach, there are 120 boards, each requiring 3 voltage rails + GND. That would need almost 500 large section cable and would be a real mess and pain to mount. The busbare also act as the support for the boards.

coppercone2:
read about the oxide growth on aluminum to get an idea of whats going on. finishing101.com has some insight (linked directly in one of my previous posts).

When I read that I wanted to no longer ever use aluminum and just pay the piper at 10x cost. fuck it. Not an option? its infrastructure essential to the function of a modern society!!!

its a train they are in service for like 70+ years sometimes, look at cuba or Switzerland. Why are you going cheap for that? people actually like trains. Its not a going obsolete in 2 years equipment. Transportation is important.

How much does a damn bus bar cost in the scheme of a fucking train even if you consider a order of magnitude cost increase??????? MTA is already going to fuck it up with unknown unpredictable means, don't make it worse. Train fires suck. They can burn in tunnels etc.

MagicSmoker:

--- Quote from: coppercone2 on February 27, 2019, 01:55:01 pm ---How much does a damn bus bar cost in the scheme of a fucking train even if you consider a order of magnitude cost increase??????? MTA is already going to fuck it up with unknown unpredictable means, don't make it worse. Train fires suck. They can burn in tunnels etc.

--- End quote ---

I guess you are directing this tirade at me? Economics wasn't a factor at all in *my* decision to use aluminum for the bus plates, rather, it almost entirely due to mechanical reasons. But I'm sure that article you read on finishing101.com has made you an expert now so...  ::)

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