Aluminium or copper in transformer windings?

[kucukerdem]

Hi,
We are manufacturing distribution and power transformers with copper winding. We are considering to shift to aluminium because of cost aspects. We are not sure about whether it is worthy to choose cost minimization instead of efficiency. Is there any one who experienced the difference or anyone who considered before? An archived thread gave me some ideas (thread248-38364) but I wanted to renew the discussion for more detailes. For ex: aluminium windings as foils-sheets or as isolated flat type conductors etc. Thanks for the replies from now.
With Respect...

 

[Iamjonscranium]

i know as far as cables go, many companies are converting to aluminum. new technology is creating new alloys from aluminum which are better conductors (than previous AL cable, not copper). i think it all depends on the customer. they may want copper for some applications, but will settle for AL for others. maybe make them in both so the customer has a choice, if that is an option.

but that is more business than science.

 

[CarlPugh]

History keeps repeating itself.
36 years ago there was a shortage of copper and we converted the transformer designs to aluminum.
There was no major problems.
The two problems with aluminum compared to copper is the difficulity connecting to the aluminum and the fact that mechanically aluminum is not as strong as copper.
We used sheet aluminum for low voltage windings.
The taps were pressure welded to the sheet.
Worked at another place and they TIG welded the taps to the aluminum sheet. Pressure welding was cleaner and quicker.
Aluminum not being as strong as copper is no problem except in extremely large or large low impedance transformers.
? If memory serves me correctly, we used special crimp lugs to make connections to the aluminum wire.
There is some data that indicates that for the same temperature rise (paper, oil insulated transformers) insulation on aluminum conductors will last longer than insulation on copper conductors.