On Wed, Jun 15, 2016 at 11:01:44AM -0400, Russell Reiter via talk wrote:
Take a look at a trolly pole then a pantograph array and tell me the pantograph needs less maintainence till EOL. You've never heard of a trolly pole monitoring station, there is a pantograph monitoring station though. It's higher voltage capacity that is the reason this form factor takes dominance in overhead wiring.
Less maintainance for the power lines, not for the pickup part on the train. The intersection switches needed for trolleypole are complex compared to the trivial wire used with the pantograph. I would be surprised if the train part of the system isn't a bit more complex to maintain with the pantograph. Of course another advantage is that a pantograph doesn't fall off the wire.
As you said higher vehicle speeds are a moot point in Toronto.
Completely.
So doesn't economy of scale account for the sensibility of starting with a higher DC voltage when part of the load is inverted back to AC for motors? I'm assuming the onboard solid state keeps the input at DC, rectifying it again would go beyond the pale.
Well the pantographs needed the larger diameter wire to get a larger contact surface anyhow. Trolleypoles seem much better at making contact around a wire, than the flat contact of the pantograph, well until they fall off. The electicity usage stays pretty much the same no matter what voltage you use, although you have some voltage loss over wire distance, which does give higher voltage a slight benefit, but 750 versus 600 is hardly enough to really matter. It all just comes down to voltage * current in the end. Incraease voltage and you decrease current and get the same result. Maybe the invertor is more efficient with some input voltages than others, but again, it isn't a big voltage difference so probably doesn't matter much. -- Len Sorensen