On 06/15/2016 11:45 PM, Alvin Starr via talk wrote:
I'm no EE, but here's my guess.
Energy losses are proportional to the square of the current and thus the square of the inverse of the voltage. (750/600)^2 = 1.5625 So they would save more than a third of the transmission losses.
I have no idea how much their transmission losses are as a proportion of the electrical power used. It has been way too long since I have done any power calculations and I believe your right. Looks like its time to brush up on my math skills.
Power is indeed I^2*R, so losses increase with the square of current. However, what's that in relation to the load? One other point that Andy Byford mentioned, when there was that power failure due to fire a while ago, is that most segments are fed from both ends, so you have in effect parallel feeds, with the resistance of each varying with the location of the streetcar along the track. So, the streetcar moves from a point directly below a point where the power is connected to the line, then moves to a point equidistant from 2 points and then to directly below another point. This adds "fun" to the calculations. ;-) Of course, you often have more than one streetcar on a segment.