Battery or hydrogen power creates just as many amps and just as much need for traction cooling. I would expect that noise envelope to be no different.
I specifically mentioned "ancillary" needs in my post.
As to "Battery or hydrogen power creates just as many amps" as as available on catenary? Far from it. And I also mentioned the duty cycle of the source. Google for "source Impedance". Unless you want to drag a freight behind with banks of batteries, but I digress.
To be fair, I've worked developing transformers and associated equipment, having to design power supplies for massive amplifiers, and it took me a few of my younger years to actually mentally model the implications of "source impedance". In audio work, the term applied to a 'soft' supply (one with a higher source impedance) is 'sag'. It's probably used in the traction industry too, if a supply line isn't of sufficient ability to match a reasonable load demand placed on it.
Putting aside locomotion for a moment, consider the challenges with 'range' on battery powered cars. The greater the battery supply to combat short range, the lower the overall efficiency. You now have to drag that supply around. Catenary addresses much of that. Catenary or third rail to a lesser extent maximizes the thrust to weight ratio. You're not carrying the 'fuel' on-board, albeit system backup control batteries are carried on any vehicle.
And electric locos are much quieter, btw. The Metrolinx noise studies showing just a few dB lower levels are highly suspect by others' results. And it's not just the noise level, it's the
type of noise, thus terms like 'white', 'pink' etc.
Children laughing can be very loud but a joy. The same measured sound pressure when crying is excruciating. Unless they're your own kids, but I digress...
And as to 'fans'...the latest electric locomotive methods of control and design have radically reduced thermal loss in motors and control equipment. That's where "chopping" comes in. The device is either fully on or off, two-state. The 'power' ( a measurement of which time is a factor) is metred by 'time division'. How long the device is on compared to off, switched at a sonic rate or higher, thus the whine from it. That's actually the motor stators turning thermal loss into sound. Resistive losses are drastically cut. And the need to cool motors so much is also reduced.
How noisy are the motor fans on the latest subway cars?
There's a myriad of technical studies on-line that I could link, but here's an example of
apparent levels, and the expected results have improved even further since this was published:
Herald confirms our electric trains are quiet
Matt L | April 23, 2014 |
55 Comments
[...]
The differences in noise levels are substantial and it’s something I’ve noticed on the few times I’ve been lucky enough to have a trip on one of the EMUs. It’s quite telling also as I still remember a conversation with a one of the senior engineers involved in the project over a year ago. He told me that while they knew these trains would be quieter, they weren’t sure just how they would compare to a carriage in an SA set (the loco hauled ones) which are noisy if you’re in a carriage near the locomotive but can be quite as you move away from it. I’ve graphed the results the Herald recorded.
Note: This Note: chart has been updated to represent perceived loudness rather than simple decibels.
The vast improvement in the exterior noise is impressive and something that is bound to be a welcome relief for those that live, work or play alongside a rail line. In fact if the figures are right then the new trains are quieter on the outside than the existing trains are on the inside. I think it will hugely improve the viability of increased densities along the rail corridor. You can get a sense for how quiet they are from this video
[...]
The Herald yesterday ran a story on
www.greaterauckland.org.nz
See also:
Mayor-elect John Tory and Metrolinx want to electrify the rails around Toronto. The Star took a ride on Canada’s only other electric commuter line bet...
www.thestar.com