Re: [OT] British vs. American English
On Thu, 2011-10-06 at 20:33 +0100, Richard wrote:
> On Thu, 6 Oct 2011 19:07:43 +0000 (UTC)
> Virgo Pärna <virgo.parna@mail.ee> wrote:
>
> > On Fri, 7 Oct 2011 02:12:53 +1300, Chris Bannister <mockingbird@earthlight.co.nz> wrote:
> > >
> > > Not sure I understand what you are saying. Unless the wrong terms are
> > > being used, but transformers "hate" DC. Plus also, think of voltage like
> > >
> >
> > I ment the voltage drop on the long lines. And that there was no device like
> > transformer for DC. Thanks the existance of transformers AC could be easily converted
> > to higher and lower voltages - shich ment, that long distance transmissions could be at
> > high voltage and converted to lower voltage near the consumer. And that was one of
> > the main reasons, why AC one out.
> > Nowadays DC current is actualy used for long distance high voltage power transmissions
> > (because of lower losses). But it's my understanding that the voltage conversion is still
> > not as easy and simple, as it is with AC.
> >
>
> Very simple, if you switch a DC voltage on and off repeatedly, what wave form do you get ?
> If the period of switching it on is shorter that the off period the equivalent output voltage is
> proportional the the width of the pulse chain, ie pulse width modulation.
> And a much higher efficiency voltage and mode conversion. A much simpler process and less lossy.
> Only recently possible with high voltage high current due to developments in semiconductor power
> handling.
That reminds me to switching power supplies. Again, I'm an audio
engineer. Perhaps those switching power supplies are more efficient, but
they cause troubles to the grid. A switching power supplies starts with
changing AC to DC, at the end it will cause AC, however, their result
are troubles to the grid. I haven't any knowledge about power lines, but
I suspect that this high power transformation might be comparable with a
switching power supply. How expend effort is needed to clean DC voltage
transformed power from troubles?
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