[USMA:24614] Re: Power & "Maytag US has SI in Specifications"

[kilopascal]

2003-01-25   You can't just double the voltage.  If you design a product to work at 240 V with the same power usage as one at 120 V, then and only then is the current halved.  If you plug a 120 V devise into 240 V, you will actually draw more current, in fact, twice as much until either the device fails or the fuse blows.    John ----- Original Message ----- From: Nat Hager III To: U.S. Metric Association Sent: Friday, 2003-01-24 15:25 Subject: [USMA:24601] Re: Power & "Maytag US has SI in Specifications"   Anecdotally, I have been told that the reason each home in the US has its own transformer is due to the problems of distribution.  If the 120 volts was carried distances over power lines voltage drop would be an issue.  By transforming the high voltage at each home this problem is minimised.     Yep.  The power delivered to the house, which does usable work, is a simple product of voltage and current.  Double the voltage and you can halve the current.     Now the current flowing through the lines to the house dissipates power according to (current)^2 times R, where R is the resistance of the lines.  Since the resistance of the lines is fixed, you halve the current and dissipate 1/4 as much power.    Nat