Re: primary solid/ tube and DC TENSION LINES

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>



Tesla list wrote:
> 
> Original poster: "Mccauley, Daniel H by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
> 
> Actually, very long distance, very high voltage tension lines are DC ! ! ! !
> 
> Dan
> 
> > Heck, skin effect is an issue for long distance 60 Hz power lines (hence
> > ACSR and bundling)
> >

And that is one of the reasons for DC! (thanks to cheap semiconductor
devices!... otherwise, that 1 MV rectifier at one end and the 1MV inverter
at the other would be a real challenge)


The other, probably more important, reason for DC has to do with the
inductance and capacitance of the long line making the system hard to
stabilize... with a DC link, one end has a constant current sink and the
other has a constant voltage source, and it stabilizes itself...  none of
this horrible stuff with synchronous var compensation, generator
synchronization, and so forth. 

I have heard that on the Pacific Intertie (a big AC link running on the
West Coast) it takes upwards of 8-10 hours for the transients to die out.
I also heard that back in the 60s or 70s when they tried to double the
capacity of the line by just running another one parallel to it, they never
could get it to work because of the coupling and transient effects.


For what it's worth bundling (running pairs or quads of wires with spacers)
is also done for corona loss reduction because it increases the effective
radius of the conductor.  It also is sort of like litz wire, in that it
reduces the overall current density (taking the bundle as a whole).