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At 03:05 PM 3/5/2004 -0500, Steven C. Barr wrote: >Aren't all the electrical systems in North America synchonized at an exact >60Hz, in order to avoid various spectacular results when they are >interconnected >(which is often the case)? I have ni idea how this is done, but I think I've >been told it was/is done... >Steven C. Barr They are not precisely synchronized. However, at least in the U.S. there is an adjustment each night to ensure that precisely 60x60x60x24 cycles transpired since the last one. Precise synchronizatin is not possible since the signals pass along wires. They travel at about the speed of light in vacuo, but even so if they are in phase at one point of the grid they are out of phase at another junction. Think of it as one grid being U-shaped between two nodes and another grid connecting at those same nodes being straight. While the result might be a phase error of only a fraction of a degree, the connections cannot depend on the signals being in phase or even precisely at the same frequency. Though all that was explained to me by someone who knew, I did not have the sense to ask how the tricks were pulled off. Mike -- [log in to unmask] http://www.mrichter.com/