barit1,
How's that again? Long distances? Swiss railways?
We were talking AC frequency, no?
In aircraft, where you transmit power only over a couple of hundred feet at the most, the losses in the wiring (skin effect, etc.) are far less significant than the gain in weight of transformers and other equipment.
When you have to transmit power to a train over what may be tens of kilometres (depending on the distance between substations), the equation flips the other way, and switching to a lower frequency than even the standard European 50Hz starts making sense. Which is was the Swiss did.