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Re: East Coast outage?
On Sat, 16 Aug 2003, Chris Adams wrote: > Basic physics. To run DC at the power levels required, the "wire" would > have to be over 100 feet in diameter IIRC. Look up the Edison vs. Tesla > power arguments for all kinds of information on AC vs. DC. Edison and Tesla's arguments took place long before switching power supplies and the development of insulating materials capable of withstanding hundreds of kilovolts. The size of the conductor is a function of IR losses. Losses are a function of the resistance of the conductor and the current passing through it. By raising the voltage, the current drops proportionally for the amount of power delivered, and hence the conductor size also drops. The problem in the Edison/Tesla days was a practical way to convert high voltage DC to low voltage (120 volts or so) power for distribution to homes and businesses. 200KV light bulbs and switches are kind of impractical for home use. :-) The advantage of AC is that a simple transformer can be used to step down the voltage from transmission to distribution levels. Before high voltage semiconductors and switching supplies, high voltage DC transmission was useless as there was no practical means to convert it to the lower voltage levels useful in homes. Rotary motor-generator sets would have been the only choice. Huge, not very efficient, lots of (big) moving parts. Not trivial to maintain. AC still makes sense for distribution, but HV DC transmission lines are becoming the norm. Think about some very large SCRs and associated parts to convert to AC for distribution. -- Jay Hennigan - CCIE #7880 - Network Administration - firstname.lastname@example.org WestNet: Connecting you to the planet. 805 884-6323 WB6RDV NetLojix Communications, Inc. - http://www.netlojix.com/