Mystery transformer wire...

[Alondro]

I have two transformers from some type of larger computer power supply. These were mounted separately from the rest of the power-supply board, and quite heavy for their size. The wire I naturally assumed was copper. However, scraping off the resin coating revealed silvery color. So I then assumed it was tin or aluminum-plated copper wire.

However, scraping down INTO the wire revealed that it's ALL this silvery metal. I've never heard of any transformer of the modern era using tin or aluminum for the wrappings of transformer coils. I would think it'd overheat from internal resistance under the high voltage and melt those two low-melting point metals too easily.

So, I've first let a piece sit in 50% nitric overnight... nothing happened! No reaction AT ALL! So tin and silver are ruled out completely. That leaves aluminum, but the wire feels too heavy for that.

I'll try with HCl, but has anyone every heard of a computer power supply transformer using aluminum wire? I took apart two similar ones, and they were typical copper wire.

Here are two pics of the mystery transformer wire.

 

[niks neims]

Aluminium seems obvious...

 

[BGDOCK]

Can you burn it with a propane torch , looks like Al to me .

 

[snail]

Aluminum windings are very common in lower quality transformers the last 20 years.

 

[Alondro]

Aluminium seems obvious...

The test with HCl appears to confirm it. Out of nearly a thousand small transformers I've dismantled, I've never seen one with anything other than copper wire.

it makes me very curious to know why these two alone use aluminum wire. It can't possibly be carrying high voltage or current. it would heat up and melt! I can only assume they're some sort of rectifying transformer, and it's simply for 'smoothing out' a lower current's oscillations.

 

[Alondro]

Aluminum windings are very common in lower quality transformers the last 20 years.

Interesting. I wonder if that's why so many modern power supplies don't last very long! All those I've dismantled previously were older.

 

[Darkthirty]

Interesting. I wonder if that's why so many modern power supplies don't last very long! All those I've dismantled previously were o

 

[eaglekeeper]

I've see combinations of aluminum, aluminum/copper and just copper windings. I would imagine higher end electronics have all copper....your picture appears to be aluminum.

 

[galenrog]

A good question from a novice. I like it.

Having scrapped tens of thousands of transformers, I can safely assume that nearly all windings are only copper or aluminum.

Cheaply made transformers will have both primary and secondary made from aluminum. Many that are designed to last a bit beyond a one or two year warranty may have primary made from aluminum and secondary made from copper, or vice versa.

Transformers with primary and secondary made from copper are, for the most part, in two categories. Those designed to meet minimum expected demand, and those that are designed to greatly exceed expected demand.

My favorite was from a batch of step down transformers from a local electricity distributor. Substation had been struck several time by lightning. All had over 150kg of 2cm flat wire. All switching contact points were a .750 silver/copper alloy. Manufacture dates ranged from 1952-1954. Lots of fun working with the rebuild crew.

Many of the smaller transformers from consumer electronics, quite honestly, were never worth my effort.

Have fun with making your scrap more valuable.

Time for more coffee.

 

[Alondro]

A good question from a novice. I like it.

Having scrapped tens of thousands of transformers, I can safely assume that nearly all windings are only copper or aluminum.

Cheaply made transformers will have both primary and secondary made from aluminum. Many that are designed to last a bit beyond a one or two year warranty may have primary made from aluminum and secondary made from copper, or vice versa.

Transformers with primary and secondary made from copper are, for the most part, in two categories. Those designed to meet minimum expected demand, and those that are designed to greatly exceed expected demand.

My favorite was from a batch of step down transformers from a local electricity distributor. Substation had been struck several time by lightning. All had over 150kg of 2cm flat wire. All switching contact points were a .750 silver/copper alloy. Manufacture dates ranged from 1952-1954. Lots of fun working with the rebuild crew.

Many of the smaller transformers from consumer electronics, quite honestly, were never worth my effort.

Have fun with making your scrap more valuable.

Time for more coffee.

It was confusing, because all other transformers in the two power supplies these Al-wired ones came from had MASSIVE copper windings, and one had a DOUBLE heat sink, a big block of aluminum and a 1/4 lb block of brass stuck together. And one of them had 30 Ag/Pd 'sausage' MLCCs on the board! Just so odd they'd cheap out on one transformer. That's what threw me.

 

[GoIdman]

It was confusing, because all other transformers in the two power supplies these Al-wired ones came from had MASSIVE copper windings, and one had a DOUBLE heat sink, a big block of aluminum and a 1/4 lb block of brass stuck together. And one of them had 30 Ag/Pd 'sausage' MLCCs on the board! Just so odd they'd cheap out on one transformer. That's what threw me.

This is just a targeted guess at best, but aluminium transformers were mounted in some electronics as low power safeguarding devices, since aluminum wire breakes (doesnt heat up or burn) if high current passes beyound its calculated limits, opposed to copper which heats up and burns before breaking.

Some electronics use instead of simple fuses, matching transformers made from aluminum therefore protecting whatever electronics are after the transformers. Not a general practice in modern days though.

Pete.

 

[Alondro]

This is just a targeted guess at best, but aluminium transformers were mounted in some electronics as low power safeguarding devices, since aluminum wire breakes (doesnt heat up or burn) if high current passes beyound its calculated limits, opposed to copper which heats up and burns before breaking.

Some electronics use instead of simple fuses, matching transformers made from aluminum therefore protecting whatever electronics are after the transformers. Not a general practice in modern days though.

Pete.

Ah, now THAT would make sense! It'd explain why these transformers were positioned outside the rest of the board, attached to the inside of the power supply wall.

 

[kurtak]

Speaking of transformers here are some pics of some LARGE transformers that I scrapped out of some industrial rectifiers (from an aluminum anodizing plant) a number of years ago - I scrapped 3 rectifiers - each rectifier had a transformer - each transformer netted between 1,200 pounds to 2,000 pounds copper (depending on size of transformer in the different rectifiers)

As you can see in the pics the transformer windings had copper tubbing wound around the coils with a coolant running through the tubbing to dissipate the heat from the transformers

Aluminum windings are quite common in transformers (smaller ones then the above) some will have all aluminum winding - some will have aluminum on one side & copper on the other side while some have all copper so scrapyards I dealt with "required" the windings be hit with a grinder to take off the coating on the wire as they paid a different price for each of the 3 different types of transformers

A bit about why Aluminum windings are sometimes used in transformers

https://sncmfg.com/aluminum-vs-copper-wire-windings-in-transformers/
Kurt