Re: Inverters on Melbourne trams

--- In TramsDownUnder@y..., John Fitzsimons <fitzsimons46a@y...>
wrote:

Question is: Do any cars running now or ever in the past on the

Melbourne system have a 600:24V inverter to provide low voltage
control power, also a battery to provide 24V power to the controls
for a get home situation to depot or suitable layby if the inverter
fails.

Hi John - long time no see!

My understanding is that the Melbourne low voltage supply is in fact
40v, not 24v.

The prospect of a battery providing power for driving the traction
motors to get home is fanciful in the extreme - as the Bendigo
pioneers of 1890 quickly found!

Let's do some sums - assuming 100% efficiency of conversion ...

160HP (old Melbourne car power) = 120KW
120KW @ 600V = 200 amps
- if you try to get that out of a 24v battery you need 5000 amps

If you can get "home" in 5 minutes you need 416 Amp hours in the
battery. That's a big battery (especially if it is going to provide
5000 amps!)

Better to get out and push, or hire a horse.

Mal Rowe




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