coulomb
Well-known member
Here in Australia, they ran/run at around 580VDC, because that's what you get when you mercury rectify 415 VAC three phase (240 V phase to neutral, we skupped the whole 110/115/117/120 V nonsense). The only reason it was DC was that traction electric motors were DC at the time. And of course two wires (one near-ground potential rail and one overhead cable) is much easier for transportation than three live wires.GRA said:Most streetcar systems ran at around 500VDC.
Yes, because of low frequency transformers.But AC won because it could cover a much larger area, so was far cheaper in terms of wire,
The other huge advantage of AC is that you can turn it off with a cheap switch. The arc is self quenching because the current crosses zero every 8.3 or 10 milliseconds. Also fuses are cheaper for the same reason. That's a major nuisance for DC over about 24 V.
Edit: yet one more advantage of AC, at least outside of North America where three phase seems to be uncommon, is that induction motors run nicely at utility frequency, at a convenient 1800 or 1500 RPM, less a little. They happily run continuously for years, and don't have brushes that wear out.