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File: 1510535207300.jpg (661.49 KB, 1530x1023, uk_eurostar_capitals_third….jpg)


third rail > overhead

Look how neat it looks.


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I will feed you just because this is going to be a fun one (and on topic!).

>3rd rail

>can't handle more than 4000 kW or so
>trip over it and die
>implying overhead isn't sexy AF and better than something that tries to hide itself


File: 1510608109652.jpg (430.14 KB, 1200x788, 20151210_542895.jpg)

Overhead is indeed terrible for showing the rolling stock clearly on the photos which sometimes is really annoying when you are trying to find a spot where at least the locomotive could be shown behind all these 100500 poles per square meter.
BUT sometimes you do get some very nice ornament of all those poles, consoles or traverses. Especially when playing around with zoom.

But indeed the overhead wire would make for much longer electrical supply sections mostly because of much higher voltage allowed and is much safer for trespassers who want to take some pictures of trains (actually it's just plain fence with no gaps whatsoever which won't let you anywhere near any railway with the third rail installed).


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BTW why do you think third rail can't handle more than 4000kW? Russian type 81-760/761 "Oka" metro EMUs, for example, in 8 cars can pull as much as 6 megawatts of power from the third rail at full throttle. We don't have electrical supply sections as short as the train itself plus minimal safe distance in our metro, y'know.

Although SIX GIGAWATTS!!!1!!!1111 /1000 was deemed as a bit of an overkill after all so newer versions introduce two motorless cars per trainset.


I had assumed current limitations from the British case. The Eurostar in the OP is very power limited on 3rd rail. I can't imagine how hot it'd get at the contact though.


Not much of a problem with heat; the shoe is copper and low resistance, it won't heat up much even drawing rated load.

The rail can't get hot because it's got a large thermal mass and would dissipate down to ambient pretty quick.

The killer on 3rd rail is resistance. Over the length of the the section the voltage drop in the steel rail is significant at high power levels, limiting the current that can be drawn.


You can't hide fatty bilevels. Only single levels can be sexy.


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dual-modes also only have 1 or 2 3rd rail shoes per power car, which for something like eurostar (2 power cars) gives 4 shoes total to draw the full hep/traction load of the train through. with gaps that might drop to 2 or 1 actually in contact with the rail, and all that current turns arcing into something destructive enough to damage the traction gear. that's why dual modes tend to carefully creep down 3rd rail, while MUs with one shoe on every truck can blast around as fast as they want.


6 gigawatts is 6 billion watts or over 500 F40PH. I don't see sny trainset pulling that kind of power.


2,515 F40PH locomotives


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I think this might be the case with Eurostar because it can have only 4 shoes for the whole trainset while Oka has whole 16 current collectors, two for each 0.68 MW KATP-2 (КАТП-2) traction drive set, just a small current for each shoe to handle.
>The killer on 3rd rail is resistance.
Although I doubt resistance is much of a problem for a very thick steel rail, while steel is less conductive than copper the 3rd rail has dozens times larger cross section. The loss of voltage might be due to current leakage into the ground which seem to me as a perfectly usual thing for the 3rd rail, especially in wet conditions.

Electric traction "outpowered" the diesel traction long time ago, dude. But damn, have you even read what was under that spoiler in >>4840 ?
spoiler: it's not 6 GW actually


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>>4839 just imagine this beauty with overhead wires, ugh


But it already has wires over head :P

And third rail cant do power because of the leakage to ground, especially when wet… or any time it dam well pleases if in DC


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