Separation of copper and iron weights in transformers 1

[edison123]

The transformer nameplates normally give the weight of core + winding together. Anyone has any idea in what proportion is this weight distributed ? Is assuming 40% is copper reasonable ?

 

[edison123]

I was talking about oil-filled transformers.

 

[prc]

This is an interesting question which was raised to me by two sources last year-one a transformer repairing company and other by a local power utility who was scrapping transformers.Then I understood the need for a separate name plate on transformers- Salvage or recycling plate or something like that.This plate should carry the net weight of copper,silicon steel,mild steel and oil used in the transformer.I am pushing industry on those lines.To get this information of a 40 year old transformer is extremely difficult-manufactuers will not be ready to search for this info.

Coming to edisons query-net weight of copper plus silicon steel will be total weight of active part divided by k. K will be 1.25 to 1.15.Trfs prior to 1975 k=1.25,1975-1995-1.2,after 1995,1.15.
Division of core by copper ratio will be 1.5-4 for two winding trfs and 1-2 for auto transformers.This depends on the loss capitalisation used at that time.If core loss to copper loss capitalisation rate is nearer to one,core by copper ratio will tend towards one.If it is high,core by copper will move away from one.

 

[edison123]

Thank you prc. I have got an enquiry for a trafo (circa 1968) rewinding and given today's copper's volatile prices, I was looking for ball park number. To be on the safe side, I will take it as 1:1.

I agree. It is time that trafo manufacturers quantify these separately on the nameplates.