On 27/07/2014 20:12, David Paste wrote:
Hello all.

The world has a few differing domestic electrical standards, 100, 120,
240 volts, 50 and 60 Hz and so on. Industrial customers have yet more.

Distribution via high voltage AC, and now DC in places.

I understand why various areas of the world have these differences - due
to historical reasons, etc.

My question is that if we were to have a brand new electrical system,
common to all areas, what would, or could, it be? Still AC? 300 volts?
Different frequency?

No real reason to ask other than idle curiosity.

When the national grid was established in the 1920s, AC was chosen for a
very good reason; its undoubted advantage for changing voltage, allowing
the use of very high voltages for long distance transmission. 50Hz was a
compromise frequency. Electric motors worked best at 25Hz and long
distance transmission has fewer losses at lower frequencies, but 25Hz
produced visible flicker in incandescent lamps while 100Hz gave
completely flicker-free lighting (some people can still detect flicker
at 50Hz) and allowed transformers to be built using less materials.

If we were starting from scratch, with today's technology, I suspect
that we might go for HVDC transmission for the supergrid, converting it
to AC for more local transmission and distribution. Otherwise, the
inevitable compromises needed for differing needs would probably end up
with us having much the same system as we have now.

If I move into very hypothetical areas, I could possibly see a move to
have residential areas supplied at 50v or less, under the elfen safety
banner. There would also be an advantage to choosing a lower frequency,
which would reduce transmission losses (around 12% at lower voltages).
The flicker effect of a lower frequency could be overcome by mandating
only high frequency fluorescents or all LED lighting.

--
Colin Bignell