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(07-26-2017, 05:59 PM)Canard Wrote: Power returns through the tracks in the ground, Kevin!
The tracks must be at a low or zero voltage relative to ground. It’s perfectly safe, electrically, to touch tracks, right? So they are, essentially, at electrical ground. Adding a bunch of water won’t change that.
As to the voltage of the overhead, it could be positive or negative (and of any sufficient magnitude for the possible current flow). I would expect that in any particular system it would always be the same, but it would definitely be possible to run motors off either positive or negative.
This does not by itself imply that an LRV can operate safely through a deep puddle — if there are high-voltage parts in the motor that could be flooded by water, you could have a problem — but the basic issue of “it’s powered by electricity”, in and of itself, is a non-issue.
Note: any electrical engineers please correct me — I took first year but don’t work in the field.
Amazingly the traffic on this thread still continues to grow.
Page 500!
First 100 pages: 12 months
Second 100 pages: 5.5 months
Third 100 pages: 4 months
Fourth 100 pages: 3 months
Fifth 100 pages: 4.5 months
The thread traffic slowed down a bit with the slowdown of construction in the winter, but now we have a late spurt of activity with the arrival of the first train.
Page 600!
First 100 pages: 12 months
Second 100 pages: 5.5 months
Third 100 pages: 4 months
Fourth 100 pages: 3 months
Fifth 100 pages: 4.5 months
Sixth 100 pages: 5 months
As the construction is tapering off, so is the pace of posting. We might be entering a quiet period now, until we start seeing the first (test) trains on track!
This photo is from the west/south side of the King/Moore intersection.
And we thought that the other side was unreasonably cramped. This is frustrating because it is so unnecessary, there isn't even an actual road. The poles (or at least one) could also have been mounted away from the sidewalk.
Hopefully the SIXO development occurs soon enough that this is only a problem for a short time.
(07-26-2017, 03:24 PM)Canard Wrote: <blockquote class="twitter-tweet" data-lang="en"><p lang="en" dir="ltr">Facing the storm - Metrolinx Pilot vehicle #1 back in Kingston after successfully completing its climactic testing at the <a href="https://twitter.com/NRC_CNRC">@NRC_CNRC</a> facility <a href="https://t.co/TX6uyped9B">pic.twitter.com/TX6uyped9B</a></p>— BombardierRail (@BombardierRail) <a href="https://twitter.com/BombardierRail/status/890288761241829377">July 26, 2017</a></blockquote>
Metrolinx Pilot LRV 1 back in Millhaven. Can't wait to see it out on the high-speed test track!
(07-26-2017, 06:41 PM)Canard Wrote: So if the polarity of the contact wire and rails were reversed, it wouldn't work? I'm assuming the contact wire is negativley charged then, since electricity flows from - to +, right?
If polarity were reversed a flood would short the circuit and the TPSS breakers would trip. In the case of normal polarity a flood would still allow the ground return to operate in the same fashion.
07-27-2017, 03:37 PM (This post was last modified: 07-27-2017, 03:39 PM by KevinT.)
(07-27-2017, 01:54 PM)trainspotter139 Wrote:
(07-26-2017, 06:41 PM)Canard Wrote: So if the polarity of the contact wire and rails were reversed, it wouldn't work? I'm assuming the contact wire is negativley charged then, since electricity flows from - to +, right?
If polarity were reversed a flood would short the circuit and the TPSS breakers would trip. In the case of normal polarity a flood would still allow the ground return to operate in the same fashion.
Nope. With the -ve of the DC source in the TPSS tied to the tracks/ground and +ve to the contact wire, a flood is harmless. If however the +ve of the DC source in the TPSS were tied to the tracks/ground and -ve to the contact wire, a flood would still be harmless because the track and ground remain at the same potential, which just happens to be +ve compared to the contact wire.
The phone companies (and the telegraph companies before them) have done it the second way since forever, because that way everything is either negative (tip) or slightly negative (ring) compared to ground, which prevented galvanic corrosion of the copper wires. I was surprised to read Schedule 15-2 Article 6 of the project documents and discover that it wasn't being done that way for transit. I'm sure there's a reason, I just don't know what it is.
(07-27-2017, 06:20 PM)DHLawrence Wrote: CTV News is doing a feature on businesses opening in Uptown now that LRT is close to opening. Someone's parked on the tracks.
The faux-brick crosswalks are now nearly complete - King and Frederick was completed last night. All that remains is Frederick/Duke, I believe, and it's actually over half done - work was interrupted by the weather the other night.