Jointing copper to aluminium wire

[RF Lighting]

Hello. Hope everyone on here is well. It's been a little while since I've visited.

I've bought a 5kVa transformer which has aluminium windings on the primary side.

The ends of the windings are connected with standard through crimps to the incoming copper wires. These appear to be the original factory connections.

One of these joints has failed completely and the other is also showing signs of thermal damage.

I'm wondering what type of connection would be the best to prevent this from happening again?

The windings are a single solid core approximately 4.0mm² CSA.

As I understand it the problems with jointing to ali to copper is galvanic corrosion, oxidisation of the ali, and deformation of the ali core. I was wondering about wago connectors as they apply a constant pressure to the joint without crushing the conductor, and they appear to have tinned contacts which I don't think react with copper. Is this likely to work or is there a better product available for this job?

Thanks.

 

[Adam_151]

http://global.wago.com/en/services/standards-regulations/terminating-aluminum-conductors/index.jsp

Not sure how available it is in this country, doubt anyone will have it on the shelf, its just whether or not the can get hold of it as a special order

I couldn't even seem to find it for sale on internet... albeit, I only spent 30s looking....

 

[Iggifer]

http://www.conrad-electronic.co.uk/ce/en/product/140202/WAGO-249-130-Contact-Paste-Alu-Plus

There ya go. Only about as much as an entire box of Wagos but if it's what Wago themselves recommend, hard to say don't use it.

Or for screwed connectors there's that (brass coloured) gauze stuff you get with bigger underground submarines because the connectors are aluminium. Dunno if you can get it on it's own or salvage a bit from somewhere.

 

[RF Lighting]

I think that paste with wagos looks like the way forward then. Thanks for the replies. This site always comes up trumps!

 

[EFLImpudence]

 

[securespark]

Oh Lordy....

 

[plugwash]

Hmm, the description of that paste on wagos site says it's for use with their "rail mount terminals", no mention of the free-floating push-in or lever activated terminals.

 

[ban-all-sheds]

I think that paste with wagos looks like the way forward then. Thanks for the replies. This site always comes up trumps!

Wago's websites seem to be brolen right now, and Conrad, being of the German persuasion, only have a German MSDS.

Might be worth asking Wago for an English one, to see if you can work out what the paste is - it might be available as something else for a lot less money, or you might be able to make your own.

 

[stillp]

Google translate can manage German BAS! This is what the MSDS states:

Mixture of purified, bleached, predominantly saturated hydrocarbons And silicon dioxide

 

[ban-all-sheds]

I wouldn't necessarily trust tools like that.

 

[bernardgreen]

Comment from a manufacturer of transformers when I asked how they would join copper tails to aluminium windings.

"" we never use aluminium winding wire ""

They build quality transformers and the minor benefits of aluminium winding wire ( cost and weight ) are outweighed by increased IR losses and the need to run winding machines at slower speed. ( to name but two reasons to not use aluminium )

 

[RF Lighting]

The joys of eBay bargains! I've decided to just try the wagos on their own and see how they last.

 

[ban-all-sheds]

purified, bleached, predominantly saturated hydrocarbons

Petroleum jelly?

 

[stillp]

Petroleum jelly?

Quite possibly. I'd have thought anything that will keep oxygen from the joint and not react with either metal would work. Personally I'd use silicone grease.