Re: The Spanish Grid Drop-out - recently released information.

On 17/05/2025 12:12 am, john larkin wrote:

On Fri, 16 May 2025 07:23:08 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:
 

Bill Sloman <bill.sloman@ieee.org> wrote:
>

On 16/05/2025 3:51 am, john larkin wrote:

On Thu, 15 May 2025 12:37:24 +0200, "Carlos E.R."
<robin_listas@es.invalid> wrote:
>

On 2025-05-15 08:18, Bill Sloman wrote:

On 15/05/2025 5:14 am, Carlos E.R. wrote:

On 2025-05-14 16:16, Glen Walpert wrote:

On Tue, 13 May 2025 07:50:36 -0700, Don Y wrote:
>

On 5/13/2025 6:26 AM, Glen Walpert wrote:

>

Another very wild idea was increasing the frequency to around 600Hz. It
would make transformers and all coiled things smaller. Planes do this.
Possibly would also radiate more. And would not help with control.

>
But our clocks would run ten times faster.
>
And everything would hum.

>
This doesn't happen in aircraft.

>
The ambient noise level in an aeroplane is much higher than in a house
on a quiet night. (Also, look up Fletcher-Munson curves to see why 600
c/s would be a lot worse than 50 or 60 c/s.)
>
Alternators for 600 c/s are feasible at a few kW in aircraft but they
are difficult to scale up to power station size.
>
Another problem with large-scale distribution at 600 c/s would be the
inductive reactance of cross-country power lines and the need for
special alloys and thin laminations to reduce core-losses in
transformers.

When it is a problem, the cross-country power lines carry DC rather than AC.

Sometimes on a commercial flight the pilot will address the passengers
and you can hear a distinct 400 Hz background noise.

Can't say that I've ever noticed it. Power supply hum getting into audio systems is evidence that somebody hasn't been as careful as they should be with their grounding and shielding, and that does happen from time to time.

And big transformers push the saturation limits of the steel, so there
will be magnetostriction. You can already hear 60 Hz hum near a big
transformer.
 Sloman has to deny anything that I say. Beats thinking.

I don't feel any compulsion to chip in when you get stuff right. If you thought a bit harder about what you posted, you'd get stuff wrong less often, and see fewer corrections. Non-narcissists see it as an invitation to raise their game, but narcissists imagine that they never get stuff wrong.
--
Bill Sloman, Sydney