Copper in locomotives

When you look inside an AC locomotive, you may notice that there is a transformer in it. You may figure out that the rating of said transformer is ≈5 MVA, its efficiency is ≈95% and the mass ≈10 tons. A utility transformer of comparable rating (same frequency – the odd 16.7 Hz in Germany, Austria, Switzerland, Norway and Sweden) would have a mass of 50 t and an efficiency of 99%.

Now, if such an efficient transformer were installed in the locomotive, it could save about 1 GWh during the loco's service life. Lugging around the additional mass would cost an additional 1 GWh of energy consumption. Hence zero profit for the additional investment of a more efficient – and bigger – transformer.

But this must not lead you to any wrong conclusions:

• The transformer is wound with copper, although the equivalent amount of aluminium would weigh 50% less. This is because the increased space requirement for the equivalent amount of aluminium would incur an additional demand for magnet steel, which is nearly as heavy as copper.
• Even though this latter argument does not apply to busbars, they are all made of copper and have always been made of copper in Western Europe, as this West German loco from the 111 series generously displays to the public.

An engineer from Deutsche Bahn AG who used to work for Deutsche Reichsbahn in the GDR summarises: "Aluminium busbars were used in the 143 series of electric locomotives at the times of the GDR (this type used to exist in huge piece numbers and is hence frequently seen also in the West nowadays). This was a disaster for the maintenance people, first of all due to the creepage behaviour of aluminium. All screwed connections had to be pulled tight again every now and then. Moreover, the contact resistances were higher, and the conductivity was lower. Further deterioration occurred due to corrosion at the contact points. But what should we do, lacking the availability of copper?"