🚀 go-pugleaf

In article <3677@tekgvs.GVS.TEK.COM>, jans@tekgvs.GVS.TEK.COM (Jan Steinman) writes:
> <<4. What percentage of the high-voltage lines that one sees in the countryside 
> are AC and what percentage are DC?>>
> <Almost all are AC...>
> 
> I don't think this is correct.  I've seen pictures of huge (I mean 40-60 feet 
> tall) thyristors, which are supposedly used for line synching high voltage DC 
> transmission lines to a local grid.  I believe the article mentioned that DC 
> transmission was efficient enough to more than overcome the conversion losses.
> 
> I didn't work out the math, nor can I recall the publication.  Anyone else know 
> something about this?
> 
> :::::: Software Productivity Technologies -- Experiment Manager Project ::::::
> :::::: Jan Steinman N7JDB	Box 500, MS 50-383	(w)503/627-5881 ::::::
> :::::: jans@tekcrl.TEK.COM	Beaverton, OR 97077	(h)503/657-7703 ::::::

DC transmission lines are used in two general areas:

	1) Where the transmission line connects two systems of
differeing frequency standards. An example of this is a large
hydroelectric power generating plant in Brazil that produces power for
two different countries. One at 50 Hz and the other at 60 Hz. DC
interconnection and regeneration of AC power solves the frequency sync
problem as well as providing better transient stability.

	2) Where the distances are great (i.e. 700 miles or more) for a
continuous line DC transmission results in lower losses and improves
transient stability. There are several long DC lines in Scaninavia and I
think DC was considered for the James Bay project in Canada but I'm not
sure if it was addopted.

For what it is worth!


John D. Proctor		|  Usenet: {ihnp4,uunet}!ingr!jdp!proctor
Intergraph Corp.	| ARPAnet: uu.net.uunet@ingr!jdp!proctor
			| US Post: 1 Madison Industrial Park
Usual Disclaimers Apply	|	   Huntsville, AL 35807-4201

A foolish consistency is the hobgoblin of little minds, adored by little 
statesmen and philosophers and divines.

		"Self Reliance" by Ralph Waldo Emerson