Lee, you said, "Another example: If there's an arc, it self-extinguishes on AC at the next zero-crossing. On DC, the arc will *continue* until some external device interrupts the flow of current." Remember if there is any plasma in the arc the AC zero crossing will not exist long enough to break the arc . I was driving down a highway with paralleling high tension lines on 200 ft high towers. (3 phase) and a lightning bolt from an approaching thunder storm, hit the lines. for a few seconds there was a 30 ft ball of plasma between the lines and a loud hiss, with a 120 hz buzz, then the circuit was interrupted, by the electric utility, and it all was back to normal, but I saw the Sun on Earth for about five seconds...
*Dennis Lee Miles * *Director **E.V.T.I. Inc.* *E-Mail:* *[email protected]* <[email protected]> *Phone #* *(863) 944-9913* Dade City, Florida 33523 USA On Wed, Jun 25, 2014 at 11:24 PM, Lee Hart via EV <[email protected]> wrote: > Robert Bruninga via EV wrote: > >> I can see that my original statement was confusing. What I meant was >> that >> for the same conductor and same I^2R loss, DC can deliver nearly 40% more >> power because the DC line can operate at the PEAK voltage rating of the >> line, whereas the AC line only delivers that same current power at RMS >> voltage, not peak. 40% increase is worth doing for long point-to-point >> transmission (with no taps) >> > > It's not that simple. Insulators have different voltage withstand > capabilities on AC or DC. You can't easily compare them. > > One example: DC always has the same polarity, so leakage currents through > the insulation cause corrosion and electrodeposition effects. This lowers > the maximum voltage that an insulation can withstand on DC. > > Another example: If there's an arc, it self-extinguishes on AC at the next > zero-crossing. On DC, the arc will *continue* until some external device > interrupts the flow of current. > > Another example: On AC, corona is more likely to occur. The higher the > frequency, the worse it gets. > > -- > Engineers like to solve problems. If there are no problems handily > available, they will create their own problems. -- Scott Adams > -- > Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.htm > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/ > group/NEDRA) > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140626/ff4f56d8/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
