Talk:25 kV AC railway electrification

Use of term "mains"
Yes, "mains" is not a term commonly used in English in North America. However, the term "household electricity" is not a suitable alternate term in this context, even though it might be in some others, since electrified railway lines are not household. If Americans don't understand the word "mains", pick a better alternate term. --144.136.125.106 06:47, 24 December 2005 (UTC)
 * "mains" is even ambiguous in Scotland - see mains (Scotland). -- RHaworth 07:56, 23 February 2006 (UTC)

50 kv AC
"Two isolated freight lines passing through desert country had double 25 kV to 50 kV to further reduce energy losses in their transmission lines." Where were these lines? Myrtone (the strict Australian wikipedian)(talk)Contrubitions


 * One is in the US, the Black River coal line, IIRC.
 * The other is the Sanhalda iron ore line in South Africa. Tabletop 06:26, 29 October 2006 (UTC)


 * I'm positive i remember reading in a book (sadly the book wasn't mine and i don't have access to it now, nor do i remember the exact title) that there was one in australia too. Plugwash 14:04, 29 October 2006 (UTC)

impractical without high voltage power electronics?!
i'm sure here in the uk we had workable 25KV trains that used mechanical tap changers for power control, indeed from the sounds i hear onboard trains it seems like some railcars with tap changers in are still running. Plugwash 02:49, 30 September 2006 (UTC)


 * Rather late but the sound you heard is more likely to be the circuit breakers. A neutral section is required between different feed sub stations.  the train driver has to open the circuit breakers before encountering the neutral section and then reclose them once he has passed.  The points at which the breakers are opened and closed are indicated by lineside signs (the markins of which, in Europe at least, often look like faces).  More modern railways such as the high speed TGV type lines have the breakers controlled automatically as the train speed is too high for line side signs to be effectively seen. DieSwartzPunkt (talk) 15:19, 25 July 2012 (UTC)


 * Are you sure this is the only likely explanation? It is actually a very reliable way of controlling motor power in DC or single phase motors. It only requires a simple circuitry and was used extensively for decades. Newer trains use three-phase motors and cannot do without more complex electronics. It is true though that higher powered motors are smallest when DC powered, facilitating the need for diodes. I think there might be quite a lot of older AC EMUs still around using this technology. I think it is quite easy distinguishing tap change sounds from those of a section break. IF the train jerks every few seconds while stepping up a notch while accelerating it is probably a tap changer (or a resistance based switching system used in DC or dual voltage unit, but that's another story). If it only clicks once in a while and is hardly felt in the acceleration of the train it is most likely a neutral section. 82.139.114.136 (talk) 09:47, 31 July 2012 (UTC)


 * Simple silicon diodes already count as high voltage power electronics. The tap changers of early 1960's era 25kV 50/60Hz AC electric locomotives worked for "wavy DC" produced by those Si power rectifiying diodes, which were attached to the variable lower voltage side of the traction transformer. That method was inefficient and DC traction motors supplied with "wavy" current needed a lot of brush maintenance for reliable commutation. Nonetheless some tap-changer locos like the hungarian V43 class are still in widespread daily use after 40-55 years (sic!) of service.


 * Starting circa 1975 with the west german DE2500, an pair of experimental diesel - AC electric locomotives hacked into pure electric vehicles, the possibility of traction via induction motors was explored again, some 45 years after the Kando V40 but this time supplied through solid-state inverter electronics (built of discrete components at the time). That movement eventually led to 1990s integrated GTO powered electric locomotives, like the Siemens Taurus and then to application of IGBT e.g. in the TRAXX and the Stadler Flirt EMU. By end of 2019 the net-gen tech of silicon-carbide MOSFET, already in use in Tesla model 3 cars, will enter railway traction application. After that very high temperature GaN (gallium-nitride) is expected in production around 2025. 79.120.158.116 (talk) 23:37, 23 November 2018 (UTC)
 * Some British tap changer locos are still in service, even a few still in the UK.  Also the first diodes used (at least in Britain) were germanium rather than silicon. Vast racks of the things, and the failure rate was appreciable, but they were still preferred to mercury. Andy Dingley (talk) 00:09, 24 November 2018 (UTC)

"accuracy"
Any one know why this;

has been sitting on this article for ages, i see no real contentious talk on this talk page to explain why, so I've removed it

Pickle 02:18, 28 November 2006 (UTC)
 * Yes look at the message above, i'm pretty sure that you can do 25KV powered systems quite practically with tap changers rather than power electronics but i don't know enough detail to correct the article. Plugwash 03:03, 28 November 2006 (UTC)


 * Based on Plugwash's comments, I have moved the   tag into the History section, where the talk about power electronics is localized.
 * This way, readers will not be misled into thinking that there is a question about whether, say, 25 kV is used for railroads, for example, or about other basic facts in various undisputed sections of the article.
 * I will try to incorporate Stevewinder's comments, below, into an improved History section, possibly with a subsection about British mechanical tapchangers, and see if that is well received and a way to resolve the disagreement.
 * --Eliyahu S Talk 20:41, 1 January 2007 (UTC)

In the UK electric locomotives of classes 81 - 87 (excluding 87 101) used mechanical tapchangers. On classes 81, 83 and 85 the tapchanging was done on the low-tension (secondary) side of the transformer, and on the other classes it was done on the high-tension side, using an auto-regulating winding. Tapchangers had 38 steps, except on Classes 81 & 85, which had 19 steps, each used twice via a 'buck and boost' system. Classes 81 - 85 had, in addition, two stages of traction motor field weakening. Class 86 had no field weakening, and Class 87 had one stage. Tapchangers were driven by an electric step-motor, except on Class 83 where an air motor was used.

Stevewinder 07:33, 26 December 2006 (UTC)


 * I strongly believe that (at the very least) this article MUST re-named. At present it is just a voltage and a frequency and has nothing to relate it to railway electrification. At the very worst I would like to have this article deleted as being "unfit for purpose" as there is more material on here about other railway electrification systems such as 50kV and 6.25kV than the main subject which is 25kV, 50Hz AC, Overhead.


 * If this article is not improved then I shall simply write another article, with a more meaningful title, and with content that is both relevant and accurate, and then make every effort to have this one removed.ALECTRIC451 23:11, 16 January 2007 (UTC)


 * If you want to rename it go right ahead noones stopping you (if your account is too new to be able to do pagemoves just propose a new title here and i'll make the move). Merging into an existing article and redirecting is also fine. Plugwash 14:16, 17 January 2007 (UTC)


 * Yes this page is incredibly useless. In the bigger scheme of things;


 * none of the other common voltages have pages (eg 1500V DC, etc), as above the title has little to do with what the intended purpose of the article - ie talk about railway electrification. The stuff that was here about the obscure voltage of 50 kV AC was interesting because that voltage is so obscure and isn't covered in that detail on the List of current systems for electric rail traction article - maybe we need a 50 kV AC article, maybe Wikipedia can cope with article on the major types of electrification - eg 15, 25, 50 kV AC, 1500V DC, 3000V DC, etc - third rail already covers extensively its voltages, but Overhead lines doesn't for its....
 * Pickle 17:22, 17 January 2007 (UTC)


 * As stated I have two problems with this page (1) The title (2) The Content. I see two solutions (a) We rename it to "Railway Electrification - 25kV, 50Hz AC, Overhead Line" (or something along those lines) and I will undertake to improve the content. (b) We abandon it and start afresh.  On balance, I am minded to choose Option (a) as this page is linked to by a large number of other articles, and I would not wish to cause disruption to the links.  If someone can help with the renaming (I am still new around here) then I shall work on improving the content, such that we make this page more useful than it currently is. ALECTRIC451 19:13, 17 January 2007 (UTC)


 * IMHO then this page is redundant, but until the other more appropriate pages are brought up to a better standard i don't favour deleting anything first. I threw together the "Railway electrification" template, to show what IMHO are the pages out there (excluding 25 KV AC). If i understand you correctly then a renamed Overhead lines article may be the best place to relocate and improve the current material that relates to all things OLE, beyond the introduction to electrification that is (presumably) Railway electrification system. I can move pages (ie rename), i can manually alter links across Wikipedia, although someone may know how to use/have access to a bot that could do it all. Pickle 21:40, 17 January 2007 (UTC)

A Proposal
I think we are getting close to a deal! We do have a page called Overhead lines and 25kV AC is a subset of that form of railway electrification system. If we moved the material on this article across to the Overhead lines article and renamed it to "Railway Electrification - Overhead Line Systems" (or something along those lines) then I would be happy to change the articles that link to this page so that they linked to the renamed overhead lines page. This article could then (with everyones agreement) be proposed for deletion (by whatever means suits people). If we can convince people that no information will be lost, then perhaps we can "close the deal". The information on 50kV railways could also be transferred to that page (I have it saved). In time, if enough material was placed on the renamed overhead lines page then a new article (or a stub) could be created. ALECTRIC451 22:20, 17 January 2007 (UTC)

Hi everybody, my name is Dario Romani from Rome, Italy, a railfan and electric traction enthusiast. It's the fisrt time I contribute in any way to Wikipedia, and curiosity attracted me to this stub. I agree it should not stand on its own and be part of Electric Traction. It should be completely rewritten as for history, starting with the Seebach-Wettingen in 1904 in Switzerland (10 KV/50 Hz), passing thru the Hollental line in Germany and the Hungarian 16KV/50 Hz system (a praise to Professor K Kando), the French takeover of Hollental and consequent birth of 25KV/50 Hz in Alsace-Lorraine, the British experience and so on, not forgetting Rheinbraun Brennstoff AG's 6KV/50 Hz (alive and well). Why dont'I do it? I am not logged in. There are already good articles on the internet. Start from buekkernet/trainspotting. I hope everybody can copy better from what's already available. Please try and make wikipedia excellent. daromany@tiscali.it

redirect to Railway electrification system
OK i know this page is bad, and we're *slowly* working on improving all Wikipedia railway electrification articles. however until thats done and all the info on this page (and its talk page) is superfluous then we can go through the proper motions and propose deletion, not just wipe it. Pickle 02:27, 11 February 2007 (UTC)


 * Good revert. As one of the opponents of this page, even I was annoyed to see it removed. I wish that people who are not part of the Wiki Trains Project would post their intentions on the talk page BEFORE taking unilateral action. Okay, I will make improvements to this page in order to protect it against deletion/redirection, but on the understanding that we rename it at some point. I hate the name of this page, but its inclusion is beyond question. --ALECTRIC451 18:39, 11 February 2007 (UTC)


 * Eaxctly there are lots of things needing doing and this page's continued existance with its current name and contents is still in doubt but proper talk, et al that is meant to happen didn't take place Pickle 21:15, 11 February 2007 (UTC)


 * Theres a lot that could be done indeed. Railway electrification system is reasonably well written, and its daughter article overhead line is where the info in this article belongs.  Overhead line lacks the electrical engineering content.  This article's content needs to be merged into it, and so as not to lose any links a redirect can be made.--Oldboltonian (talk) 20:55, 29 April 2019 (UTC)

mention opposite phase wire used
a possible and possibly common thing done with 25 kV overhead wires is having an opposite phase 25 kV line also, which means a total of 50 kV between it and the normal wire. this may be an extra wire above the ground, which then serves 2 purposes: - reduce electromagnetic interference - be used together with booster transformers to reach a longer distance with fewer substations.

this is used in the netherlands for 25 kV overhead wires, and possibly elsewhere (look for the presence of an extra, separately insulated, wire in an overhead line system)

this is explained on the dutch wikipedia: http://nl.wikipedia.org/wiki/Spoorwegtransformator Bewareircd (talk) 00:43, 27 November 2008 (UTC)


 * See also: Central_Organization_for_Railway_Electrification and Amtrak's_60_Hz_traction_power_system. Biscuittin (talk) 21:00, 23 November 2011 (UTC)


 * I have added a new section "2 x 25 kV autotransformer system". Biscuittin (talk) 22:53, 23 November 2011 (UTC)

kolkota metro
http://en.wikipedia.org/wiki/Kolkata_Metro and their website both say it is still on DC give them a call and ask them if you please :) other than Delhi metro none of the mass transport rails within a city use AC

In an overhead caternary always used?
Is it true that all or most 25 kV systems use an overhead caternary system of electricity delivery? If so, we should mention this in the opening paragraph. I would add it, but I'm not sure what is the accurate summary of affairs. All the 25 kV systems i know about use overhead caternary, but I'm by no means an expert. Cheers —fudoreaper (talk) 09:07, 13 February 2009 (UTC)


 * For high voltages an overhead wire is always used due to the great clearances required. A 3rd rail cannot be used with high voltages because sparking and leakage would be too great. 82.139.114.136 (talk) 12:53, 28 May 2012 (UTC)

Single phase powerlines when 25 kV AC is used
The advantage of using 25 kV AC with 50 Hz respectively 60 Hz is that the current for the catenary can be got easily from the power grid. Nevertheless for the supply of some TGV lines in France single phase AC power lines were built, as some pictures on http://www.justmystage.com/home/overheadtml/france1.html show. Why? —Preceding unsigned comment added by 91.46.242.193 (talk) 16:45, 6 June 2009 (UTC)


 * Three phase power systems work best when the load on each phase is roughly equal. This is hard to achieve on railroad electrification systems and the French may have decided it was better to transmit single phase AC for some segments.--agr (talk) 17:10, 19 July 2009 (UTC)


 * Single phase electricity will hardly ever be created due to the fact the power deliverance is sinusoidal and not continuous. I expect the single phase grid in France comes from a three phase grid somewhere, but is distributed from a single point. To prevent imbalance VAR compensator's are sometimes used. 82.139.114.136 (talk) 12:45, 28 May 2012 (UTC)

Disadvantages
narrow gauge with 25kV AC: more disadvantage? narrow gauge with 25kV AC in snow and/or steep grade: much more disadvantage? 121.102.47.215 (talk) 05:53, 13 March 2010 (UTC)


 * What is the relationship between the gauge and the disadvantages of 25kV AC?--Bk1 168 (talk) 07:53, 28 May 2010 (UTC)


 * Usually narrow gauge tracks are built in locations where there is only a small clearance and a lot of sharp bends. Especially in these conditions the construction of a high-voltage overhead wire can be a big pain in the ass. High voltages are in use on narrow gauge tracks though in Switzerland (15 kV 16 2/3 Hz). 82.139.114.136 (talk) 12:51, 28 May 2012 (UTC)

UIC standard
UIC standard voldages:

DC voltage: 3 kV AC voltage: 25 kV (50 or 60 Hz) 121.102.47.39 (talk) 12:02, 22 May 2010 (UTC)

Image used is not 25 kV overhead equipment
The image used is that of the Swiss railways, which use 15 kV 16,7 Hz, so the image is incorrect because it doesn't represent a 25 kV system. I found the image in use in other articles too (21st Century modernisation of the Great Western Main Line and Railway electrification in Iran), both about 25 kV electrification. Is there really no other image available? I will see whether if I can get one here in Holland, but the 25 kV network here is very small (two lines) and far away (it has been constructed similar to the French high speed network, relying on the use of the existing infrastructure near the destination using multiple voltage loco's), the rest is electrified with 1500 V. Furthermore, a part of the system was built with funky circular bent style poles that might not be typical of the way these are usually constructed. 82.139.114.136 (talk) 10:06, 31 July 2012 (UTC)

-edit: I found an image of the Dutch electrification on the Betuwelijn goods corridor in southern Holland on the Dutch Wikipedia showing the uniquely styled overhead poles. I heard they are sufficiently high to allow double stacked containers. At the moment it ends on standard clearance tracks, so double stacked containers will not appear any-time soon on this line, but it might explain the investment in non-standard equipment. It also shows the 2 x 25 kV system described above with an extra wire. (There is also a grounding wire that is connected to the poles without an insulator). 82.139.114.136 (talk) 10:40, 31 July 2012 (UTC)


 * 20080513-335-Thessaloniki-120016.jpg
 * This photo, taken at Thessaloniki New Passenger Station, Greece, shows a class 120 electric locomotive fed from 25 kV overhead lines. SV1XV (talk) 10:55, 31 July 2012 (UTC)


 * I'm still looking for a photo which shows the overhead equipment more clearly. This one is clearly centered around the locomotive (which is a nice one though). I will see if I can find one that is similar to the 'Swiss' one. 82.139.114.136 (talk) 19:47, 31 July 2012 (UTC)

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2 x 25 kV autotransformer system - error
The text of this says Periodic autotransformers divert the return current from the neutral rail, step it up, and send it along the feeder line. However, this is not true.

What happens is that the autotransformer splits the return current and only half goes to the feeder, the other half goes to the overhead line. This means that in the overhead line, half the current is supplied from the supply transformer connection, the other half is supplied by the autotransformer. The supply transformer drives half the current via the feeder line, in antiphase to the overhead line, which is actually the half of the return current in the autotransformer which goes to the feeder.

The requirement for ampere turns balance on the autotransformer requires that the return current is split to go half and half to the overhead line and to the feeder.

Now, I am very wary of altering the article, because some Wikinazi is likely to come along, demand a citation, at which point, I will point to the Wikipedia article on autotransformers, which has informed my understanding of this. And I will have to explain in some detail why the ampere turn balance requirement works this way for 2 * 25kV systems and even justify ampere turn balance on transformers, at which point, someone who does not understand something like "magnetising current" will say "ah but there is no real ampere turns balance" and then I explain this and the whole thing is ruled out of order as being original research, any change I make to the article is reverted and the article stays wrong. 78.33.185.122 (talk) 12:28, 29 April 2020 (UTC)

Tweet by author
There's an interesting tweet today, here, by the current author of a book on OLE saying that the explanation of autotransformers given in the book has been wrong for years and giving the version that will be included in a new edition. Perhaps someone with better understanding than mine could check to see if anything in this article needs changing. --Cavrdg (talk) 20:16, 3 August 2021 (UTC)

Move suggestion
This article has not been focusing on 25Kv AC per se, but rather on the use of utility frequency power supply, which is typically 50 or 60Hz. All systems mentioned here use utility frequency, but not necessarily 25Kv. As a result, I suggest that this page be moved to a more appropriate title. Some possible ideas: utility frequency railway electrification, 50Hz AC railway electrification, high frequency AC railway electrification etc. Any thoughts? Mako001 (C) (T)  🇺🇦 02:10, 11 September 2022 (UTC)

There's already a separate page called "Railway electrification system" which covers all standards used worldwide; I think the systems that do not use 25 kV should be relocated to that article instead. Aliew (talk) 01:50, 8 January 2023 (UTC)

Saudi Arabia's Haramain high-speed railway
The utility frequency in Saudi Arabia is 60 Hz, while this article says the Haramain high-speed railway uses 25 kV 50 Hz. Is it an error, or is there a dedicated facility generating electricity at 50 Hz solely for the Haramain high-speed railway? Aliew (talk) 21:31, 5 January 2023 (UTC)