(Much Snippage ... about power line frequencies not at 60 Hertz (or Cycles per Second)
One of the down-sides to 25-cycle power was that _transformers_ had to
> be built heavier for the lower line frequency. Stuff that was build
> with the existence of lower frequency power worked just fine when
> connected to a higher-frequency source. Unfortunately, when you took
> something that had been designed to be 'just adequate' on 60-cycle
> power, and plugged it into a 25-cycle source, a frequent result was
> 'letting the magic smoke' out of the transformer. A *RUDE* surprise
> for someone who moved into one of those 25-cycle 'islands' from the
> mainstream of power distribution.
Transformer weight is one of the big reasons much aircraft AC power operates at 400 Hertz. MUCH smaller transformer cores = less weight = greater payload or smaller engines.