Yup, that's quite true. However, our local power supplier apparently isn't doing that for most of the power lines, just the ones from the mainland of North America to Vancouver Island, under the Gulf of Georgia. Which is an interesting concept, given that the lines are in salt water, are subject to some pretty significant tides in some places, and are subject to transient underwater traffic (it's a Top Secret matter, you're liable to 25 years in prison if you ask why and I tell you) that sometimes has been known to sink Brazilian fishing boats.
Our system ain't new by any means, TAE's initials are still on some of the pieces of equipment -:) -:), but Hydro goes by the old electrician's (and mechanic's) rule, IIDWDFI. Pat -----Original Message----- From: Robert Derman [mailto:[EMAIL PROTECTED] Sent: 2008/05/29 09:16 To: [email protected] Subject: Re: [social] I am not receiving anything from this list Pat McBride wrote: > However, DC doesn't really work all that well over long distances, measured > in miles (or KM) and has to be boosted every so many miles. The power lines > in BC that we're talking about go for about 500 miles or so, use 3-phase > power, and therefore it's cheaper in cost of transmission wire to use AC. > The newest systems use DC transmission at 500 KV or so. The higher the voltage, the less the power loss per mile, at least as far as resistance losses is concerned, and those are the ones that dominate. This loss is exactly the same with AC or DC, only the voltage matters, not whether it alternates or not. Induction losses are a lesser but still very significant factor. AC losses are of two types, simple induction losses, where conductive materials in the vicinity of the transmission line develop local currents which are parasitic, like the farmer's coils, and the second is the tendency of the lines to act as a huge radio antenna radiating 60 Hz into space. That is also power wasted that doesn't occur with DC. The reason that DC was not used until recently is simply that converting DC back into AC so that transformers could step it down was very expensive, and therefore impractical. Solid state oscillators have greatly lowered the cost of doing this and therefore made it practical. > -----Original Message----- > From: Robert Derman [mailto:[EMAIL PROTECTED] > Sent: 2008/05/27 15:11 > To: [email protected] > Subject: Re: [social] I am not receiving anything from this list > > > Ian Lynch wrote: > >> On Tue, 2008-05-27 at 13:14 -0500, Robert Derman wrote: >> >>> This is why a lot of the high power transmission lines now use direct >>> current rather than alternating current. There was just too much >>> induction loss. >>> >>> >> Snag with transformers then? I would have thought the additional cost of >> stepping up and down voltage would have made it uneconomic for general >> use but then again technology changes so maybe I'm just out of date :-). >> >> Ian >> >> > Solid state oscillators turn it back to AC at its destination so that > transformers can step the voltage down. The cost of doing this is far > less than the value of the energy lost by AC losses. > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] No virus found in this incoming message. Checked by AVG. Version: 8.0.100 / Virus Database: 269.24.2/1471 - Release Date: 08/05/28 17:33 --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
