On 07/07/2013 18:19, John Williamson wrote:
Andy Bartlett wrote:
"John Williamson" wrote in message
Another way to save money on the grid would be to increase the
frequency, allowing the use of smaller transformers for the same
power. The same objections apply, although aerospace applications
often use 400Hz AC for this reason.

Trouble is even though substation efficiency would increase, your main
transmission line losses will increase dramatically due to skin
effect. It is still significant even at 50Hz.

Conflicting requirements. DC is best for long distance transmission, and
HF AC for smaller transformers...... It's Edison vs. Westinghouse all
over again. Grin

Could this be the reason why we use 50 - 60 Hz worldwide, as the best
compromise for a national grid?

Apart from skin effect, 50-60 Hz keeps the generators simple: two poles
per phase at 3000 rpm or occasionally 4 poles at 1500 for 50 Hz. You
can't speed up big (500-650 MW) the generators significantly because you
are close to the strength limits of suitable steel. You have conversion
losses if you try to increase the frequencies with electronics. The
losses in DC converters at each end of a DC link (like the
interconnectors under the English Channel are offset by reductions in
transmission loss.