Electrical Aluminum DC Busbars - Joint Coating of silver, tin or nickel 2

[KenAlmon]

Just wondering if there is any consensus on approved coatings for subject busbars handling 7000+Adc?

Specifiers and suppliers from Europe tend to use nickel per ISO 4526/4527 as a plating material.

North American suppliers tend to supply tin or silver as the recommended choice, although I have not seen any IEEE/ASTM standards (ASTM B689 notwithstanding) that recommend nickel for this purpose of coating joining surfaces of electrical busbars.

Does anyone know of any North American standards relating to using nickel plating of joining surfaces of aluminum DC busbars, specifying thickness, smoothness etc.?

I would think the smelting industry would deal with this regularly - perhaps someone could quote common uses in that industry? But perhaps they only use copper?

Thanks

Ken

 

[Gr8blu]

Choice of coating material (Ni, Sn, Ag, etc.) may be based on material used for connections (e.g. plating on associated lugs) - or it may be in response to local atmospheric conditions (silver is a better conductor, but reacts with H2S and other similar chemistries). Tin reacts less, but still some. Nickel reacts even less, has better "hardness" characteristics but is a much poorer conductor.

Might even just come down to cost and/or local environmental protection agency considerations - i.e. who allows what kind of plating process (and its byproducts).

Basic surface finish is going to be either bright or matte - again, depending on what is connected to it. If you want to find a standard, try looking up under copper bus instead of aluminum (because there is a LOT more Cu bus out there).

Converting energy to motion for more than half a century

 

[electricuwe]

A busbar joint is much more complex as commonly considered. The performance is a combination of busbar material, coating,clamping hardware and maximum temperature. I can confirm that in US silver is preferred, at least on Cu, whereas the rest of the world prefers other coatings. Some of our customers have their own propietary solution for the coating.

On Al vs. Cu: Cu is more "forgiving" in regard to poor design or workmanship, but Al buswork is much less expensive especially from material cost point of view. Therefore Al buswork is more common in large installations done by people who know what they do.

 

[che12345]

I have the following opinion for your consideration.
1. Silver is the best over tin or nickel, under any consideration either contact resistance, environmental, temperature-rise and durability...
2. Silver plating would be more costly, but consider only the small contact areas (not the whole length of the heavy 7kA bar); the additional cost would be minima.
3. Normal electrolytic plating process would have a good smooth finishing surface, which does not require any further surface treatment. I suggest say 5um thickness would be fine for bolted joints, NOT subjected to arc erosion.
Che Kuan Yau (Singapore)