bogey780
join:2004-03-19
Here
| reply to verolom
Re: Clue
'most dwellings have two loops, each is 24AWG or thicker'
Correction: most dwellings may have two loops, each maybe is 24AWG or thicker.
DC doesn't work that way. It doesn't run like AC which is why Westinghouse won and Edison lost when it came to standardization. You can't transmit DC long distances effectively unless you have high gauge wiring and enough of a step-up to reduce voltage drop. |
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shdesigns
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Premium
join:2000-12-01
Stone Mountain, GA
 ·Atlantic Nexus
| DC transmits better than AC. There are now several DC high-V power lines. They use DC because you don't get the reactive loss of the lines.
The problem with DC on mains power is you can not step it up or down. Edison had to run everything on one voltage because he could not step it up or down. Westinghouse (Tesla) could step up the voltage for lower losses, then step down locally.
As far as the local loop, I have worked with devices powered over 24GA wire. For a device that used about 8W, at 24 volts, the best we could do was about 700' on a single pair and 1000' on 2 pair.
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Scott Henion
Embedded Systems Consultant, shenion on #ATU @irc.freenode.net
SHDesigns home |
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bogey780
join:2004-03-19
Here
| Thanks for the info on HVDC.
The way I took it the loss and inability to step effectively is what killed DC because placing power plants locally killed the idea for most Americans. While AC could be transmitted at high voltage and stepped down to low voltage locally.
Either way, that's why I liked BellSouth's FTTC engineering. It used 22ga cabling to power 130VDC systems. I could see an eventual move to FTTH from there could possibly allow for telco provided power to the house (which was within 1kft always). |
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