Uncle Monster explained on 12/25/2016 :
On Saturday, December 24, 2016 at 9:46:57 PM UTC-6, wrote:
On Sun, 25 Dec 2016 02:13:52 -0000, "James Wilkinson Sword"
wrote:

The 50hz transformers are larger than 60hz transformers. Aircraft power
systems often run on 400hz AC power and the transformers in the avionics
are much smaller and lighter than the terrestrial 50 and 60 Hertz
transformers. ?(?)?

http://www.engineering.com/Electroni...-and-60Hz.aspx

[8~{} Uncle Hertzian Monster

So why don't any countries use a much higher Hz?

Interesting question.
Tradition I imagine. Once you are locked into a frequency, changing is
very expensive. Motors and clocks won't work for one thing.
There might also be issues with transmission losses.

I was thinking the same thing about transmission losses at higher frequencies
because I also have a background of working on RF equipment. I held a license
as a broadcast engineer but did most of my work on two-way radio. I'm
guessing a high frequency electrical distribution system would require
shielding which would make it more expensive. I believe the generators would
also have to spin faster. Every genset I ever installed was a 60hz unit that
spun at 1,800rpm. I wonder if a 400hz genset would have to spin at 12,600rpm
or have some sort of frequency converter system on a genset spinning at a
lower rpm? The gas turbine APU's for aircraft can definately spin at high rpm
so I'm wondering about the power units that the aircraft mechanics roll up
and plug into the aircraft while they're working on them prior to flight. I
suppose I have some research to do. ヽ(ヅ)ノ

[8~{} Uncle Power Monster

My first thought was skin effect, but that is a very small factor under
1000 Hz. I don't think propagation would be much of a factor either if
the systems were designed properly.

I'll go with 'tradition' as the major factor. Most 'end user' devices
here are engineered with filters to reject harmonics of the 60 cycle
system, or rely on the 60 cycle broadcast standard.

https://en.wikipedia.org/wiki/WWVB