The trick is to get high voltage for transmission and low voltage for users. Back in Edison's and Tesla's time the conversion from low voltage to high voltage and back for a DC system could not be accomplished easily like we do today. It is easy to convert AC voltages - you use a transformer. DC voltage changes require more sophisticated electronics. Edison could not convert the DC voltage and so had to use low voltage generators. Low voltage has significantly more loss than high voltage. Loss is inversely proportional to the square of the voltage, and is independent of whether the voltage is AC or DC. That's why Edison's system could not go long distances. Tesla and Westinghouse had the advantage of easy voltage conversion. High voltage DC systems require smaller, simpler conductors than AC systems because of skin effect. The transmission line cost is lower. That is the reason DC is sometimes used for long distance power transmission. Nicola Tesla - surely an unrewarded super-genius. We need someone like that today. BTW, the telephone company does use the earth for a return path for the bell signal. It turns out that the earth really has a pretty low resistance. If the power company is getting "ground" currents, I suspect a fault in the transmission line. Brent ________________________________ From: Larry Holmes <larry@kijoda.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Tuesday, October 23, 2012 5:53 PM Subject: Re: [Utah-astronomy] Science Friday: Tesla Interesting point when comparing Tesla's DC system with Edison's DC. You out there may or may not know that the Intermountain Power Plant in Delta, UT generates AC but converts it to DC for transmission to Riverside. CA where a 2nd converter station restores it to AC. The line is, I believe, some 700+ miles long, and they experience less loss with DC than AC. Must have been quite sizable to pay for the 2 converter stations, but a drop in the bucket when compared to the total cost of the plant. So, we burn Utah coal, to furnish electricity to CA, because LA Water & Power could not get a permit to build a coal-fired station in CA. The Delta station is owned by a consortium of CA cities to which the electricity is distributed. This really does not have anything to do with astronomy (for which I apologize), but does tie in with the Oatmeal discussion of the two men. The author could use a little soap in his mouth. Anyone remember that one? I %%#@#&** sure do. 73 On 10/22/2012 6:14 PM, Wiggins Patrick wrote:
I just finished listening to a podcast of last Friday's edition of Science Friday. The subject was Nikola Tesla. In case you heard the piece and wondered about the Tesla cartoon they referred to, here it is:
http://theoatmeal.com/comics/tesla
Caution, there are a few spots where the language is PG-13.
And here is the podcast.
patrick
Sent from my iPad _______________________________________________
_______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".