Yes, and thereby lowering the I squared R losses making long distance transmission of electrical power possible.
For those who don't understand: To double the power through a wire you can double the voltage OR double the current or a combination of the two. However, as you increase current in a wire, (holding the resistance (using the same size wire) and voltage steady), the losses from heating the wire with the current flow increase exponentially to the square of the current increase. This is called "I squared R losses". Thus to transmit power at a distance it is cost prohibitive to increase the current because you would have to increase the wire cross-section area exponentially to keep the losses the same. One must therefore increase the voltage at the generator end and then reduce it again at the load end. This is easy (inexpensive) to do with a transformer using ac, difficult (costly) to do with a motor-generator set using DC. This is why ac is the only practical way to transmit electric power for a distance of over a mile or so. Three phase ac is the second half of the scenario. Imagine three coils of wire arranged 120 degrees apart around a magnet rotating like a spinning compass needle (but stronger). The magnet pushes and pulls electrons too and fro through the wires in each coil as the north and south poles pass each coil creating alternating current flows in the wires of each coil 120 degrees of phase apart. Connect another similar three coils of wire some distance away to the first three coils and you will have a rotating magnetic field in the middle of the three coils much like the magnet rotating inside the first three coils. If you place a magnet there, free to rotate, it will follow exactly the rotations of the first magnet. Increase the power and efficiencies through development and there you have how almost all the generators and motors in the world work today. One or the other of the three phases is used separately for small loads such as houses and boats. BTW - Home Power magazine has standardized using upper case for DC and lower case for ac: I don't know why. They also standardized the use of common 240 vac electric outlets for DC outlets, codified by the US National Electrical Code as long as there are none of these outlets used in the home for 240 vac. Norm S/V Bandersnatch Lying Julington Creek 30 07.695N 081 38.484W > Subject: Re: [Liveaboard] electricity > > Norm of Bandersnatch wrote: > > > > It wasn't that way. > > > > There was no way DC could be used for electric power > > transmission because of I squared R losses. > Yes, but to be even more accurate it was because AC could easily be > converted to different voltages with transformers, where DC could not. -Ken > _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
