A new trend in wire technology.

[SeanB]

Today i took apart a microwave oven transformer. The usual cut the 2 welds at the bottom, tap the I core section off and gently remove the 3 windings in one piece ( mostly). The windings were way too light at first feel, definitely not as heavy as the regular copper windings on these transformers. A little scraping and there is a new wire material being used. Enamelled aluminium wire, in 20SWG and 28SWG, used for the primary and secondary winding. About half the mass of a copper winding.

Just thought I would caution all those buying enamelled wire on eBay to be aware that what you can get is not copper, and may not be easy to solder to, if at all. This likely will be a more common thing in transformers in the future.

Microwave was only about a year and a half old when the magnetron decided to die. Did not have a suitable magnetron in my collection to replace it, so turned it to scrap.

[BravoV]

Brand & model ?

[liquibyte]

I also discovered the exact same thing in a Samsung microwave transformer I just took apart.  I'm not sure if it's pure aluminum or an alloy but it's definately not copper.  I figured I'd just rewind the thing with proper magnet wire one of these days.

[SeanB]

Generic OHL cheapie. They are used a lot and generally will fail after a while. Normally the diode or the capacitor goes, but this one did it proper. Available in many makes but always the cheapest one on the market with a dial. Wonder why they put a power selector on these, they always are left on max power, 700w or so. At least the fan windings were copper.

[deth502]

miller welders also makes hobart as their economy models. i have a hobart model that is exactly the same as the comparable miller model with the difference of the transformer winding in the hobart being aluminum while the millers are copper, and also the heat range on the hobart is a 4 position switch while the millers have a variable rheostat for fine adjustment. the wire wound rheostat and tranformer are how they keep the costs down for the economy models, they have been doing this for well over 10 years now.

[Zero999]

Nothing new aluminium has been used as an electrical conductor for years, not only to save money but because it has a higher conductance vs mass than copper.

[SeanB]

I have an old air cooled arc welder with aluminium windings on the secondary. Not unusual to cut mass but very unusual to see a 28SWG aluminium wire that was not terribly brittle. Most of the time they are going to be incredibly work hardened by the drawing to that size. Hard as well to get the enamel to bond to it, it scrapes off very easily. Not good for reliability. I have seen aluminium wire used in speakers, but those always have crimped terminations to the woven copper leadouts.

[cybermaus]

A lot of the twisted pair ethernet wiring (CAT5/5e/6) is aluminium too. Especially the budget solid core ones.

[NiHaoMike]

A lot of the twisted pair ethernet wiring (CAT5/5e/6) is aluminium too. Especially the budget solid core ones.

I have yet to come across one of those but I have come across copper plated steel. Copper plated steel is also regularly used in coax cables and at high frequencies, works every bit as well as solid copper.

[senso]

Not wire, but foil, in the secondary of my old bi-phase arc-welder, good for 200A, only a massive transformer inside the metal case, it has at least 20 years, so not a new thing.

[6E5]

Yeah MOTs have been using AL wire for years, ever since Manufacturers realized that its the consumer that pays for wire.

On a related note, one of my research projects for school have been using silver as a conductor, rather than aluminum, in 3 phase induction motor rotors. Honestly I think it's a silly idea but eh, not my money!

[johnwa]

I have yet to come across one of those but I have come across copper plated steel. Copper plated steel is also regularly used in coax cables and at high frequencies, works every bit as well as solid copper.

That reminds me of the test leads I bought from DX recently. They looked fairly average quality, though not too bad for the price, I thought initially. However, recently I put one down on the bench, right next to some rare earth magnets, and ... the magnets stuck to the wire!  Resistance was over an ohm. You get what you pay for I guess.