How to determine winding material?

[linehand]

Referring to a GE 34.5-4160 3000kva substation transformer. I cannot determine the winding material. The nameplate does not indicate. I searched into company archives.It was ordered in 1951 and installed in 1952. The prints or bid specs do not indicate. Is there any posibility that there are aluminum windings in a unit of this vintage?
Any insight is appreciated.

 

[dpc]

I think it is highly unlikely that a transformer built in 1952 used aluminum windings.

But I suspect that if you have a serial number from the nameplate, GE can track the information down. They have found information on much older equipment for me.



David Castor

http://www.cvoes.com

 

[linehand]

Thanks DPC. I already have contacted GE and ran into a dead end. any contact info would be appreciated.
I agree on the date but unfortunately I need to prove this.

 

[PHovnanian]

I wonder if there might be some sort of chemical test one could do on an oil sample to look for trace amounts of whatever the windings are made from.

 

[rhatcher]

I agree with dpc that it is highly unlikely that you have aluminum windings in something that old. If you really want to know, I would think that you could remove one of the bushings and see what tye of wire is connected to it.

 

[linehand]

My reasoning is; I am sending for bids on this unit for removal in October. I cannot remove the bushings until that time as it is still in service. Oil sample is a good idea as well. I think I'm confident enough now that the windings are copper to claim it as such.
Thanks.

 

[mmt019]

I'm with rhatcher on this one. I work at an Air Force Base with 1940's-1960's transformers and I have never seen aluminum windings on a transformer. They built transformers like tanks back in the 40's-60's. This is a "utility grade" transformer

Reasons why I think it is copper:
1. Size is the overriding practical reason for using copper. Utility transformers are designed with very large short circuit tolerances, because of the size of the grid and the magnitude of the current flow in the event of a fault. The windings have to be both large enough to handle those currents and strong enough to withstand the mechanical loads they impose. Aluminum's (volumetric) conductivity and its strength are much lower than coppers, so an aluminum transformer that matched the kVA rating of, say, a 400-MVA copper unit would be huge! It would be too large to transport, and utility or substation transformers are not items that can be assembled on site. All of the transformers we make are copper-wound; even so, we have to ship the larger ones by rail. Size can also be important in transformers installed in high-rise buildings, where space is often at a premium.

2. Utilities did try aluminum back in the 1970s. Interest rates and inflation were high then, and first-cost considerations got in the way of conventional wisdom. Some utilities bought aluminum-wound transformers because they were initially less costly. They ended up having many more failures than with copper transformers, and, as a result, utilities won't touch aluminum today for transformers in our size range.

 

[prc]

mmt019, we are talking about 3 MVA transformer and not 400 MVA ! Incidently, ASEA made a 250 MVA unit with aluminum winding during 60's or 70's.That is the largest aluminum wound transformer ever built.Technology for aluminum wound transformers is well established and many times there were shifts from copper to aluminum ( in the small transformer range ) depending on the volatile copper prices.Even today in certain markets, aluminum wound transformers are popular.BUt I dont know situation in 1951 in US.

The type of query raised by linehand is raised quite often and I used to suggest to utilities to insist for a rating plate with all new transformers indicating the net weight of copper/aluminum, silicon steel, steel and oil contained in the transformer so that at the end of life, owner is aware of the salvagable value.