RE: Why no corona? AC / DC transmission lines

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Ben McMillen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <spoonman534-at-yahoo-dot-com>

Hi all,

> Sure, there are transmission lines that run up to 768kV
> or better. 
> I've even heard of megavolt lines (anyone know where
> these are?)

One of my profs here at the University was invloved with
westinghouse when they were testing 1MV transmission
lines.. apparently, they were unpredictable and could not
be modeled.. he said that they would frequently arc over to
stuff that was further away than the nearest ground, so
they decided that 768kV was as high as they could 'safely'
go.. I believe that was for AC though.. I'll have to
check.. ;)

And on the subject of corona.. Isn't it still there? We've
all been around power lines (esp. high tension lines) just
after a rain storm.. you can physically HEAR the air being
ionized.. isn't that corona? (just not visible.. )

I just remebered, 768kV was the highest they cold go with
AC.. 1MV DC lines do exist.. (my bad.. ;) )

Coiling In Pittsburgh
Ben McMillen


> 
> >>>>>>They have quite a few now 1 Megavolt DC
> transmission lines which are
> basically bipole
> transmission lines (+/- 500,000VDC).  Seems Edison could
> be happy right now.
> DC high voltage lines are run
> because of their lower reactive losses and are under a
> lot of study right
> now.
> I think i heard before that over 30% of power is lost in
> AC high voltage
> power lines just due to losses.  Of course in DC
> transmission lines you do
> get a large amount of losses in the step-up / step-down
> converter systems.
> 
> 
>  that run 
> across deserts. But the vast majority of power lines are
> small, under 
> 14.4kV. Also, while we run at 400kV regularly, their
> 400kV would act a lot 
> differently. Even though the voltage is the same, the
> frequency is a lot 
> different. And weather it's a megavolt line across a
> desert, or the 120 in 
> your wall outlet, it's ALL at 60hz. Things get freaky
> with frequency.
> 
> >>>>>>>>Not really, DC tranmission lines exist and they
> have just as much
> corona as 60Hz lines.
> 
> Dan
> 
> 
> 
> 
> 
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> 
> >Original poster: "Richard W. by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" 
> ><potluck-at-xmission-dot-com>
> >
> >Hi list,
> >Was wondering.
> >Power transmission lines, before a substation, can carry
> from 100Kv to more
> 
> >the
> >600Kv. So why no corona? Seems we battle corona quite a
> bit at much lower
> >voltages. <shrugs>
> >
> >Rick W.
> >Salt Lake
> 
> 
>