Talk:Overhead line

Name

Where should this be moved to? overhead line? overhead lines? overhead power transmission? --Robert Merkel

Comparison with streetcar/tram style lines could be interesting

I'm curious about what differences there might have been with old equipment used for streetcars. A lot of those vehicles had straight collection arms (instead of pantographs) with pulley-style wheels on the ends. Managing a transition between breaks would seem to be more difficult, and speed would seem to be an issue (although I know such systems ran at up to 100 km/h in the early 20th century in my region of the U.S.—possibly not over breaks, but certainly in between them). —User:Mulad (talk) 14:06, Sep 29, 2004 (UTC)

History

I removed this:

The use of overhead cables conducting electricity, invented by Granville T. Woods in 1888, amongst several other improvements by Woods, led to the development of electrified railways, the first of which was operated at Coney Island from 1892.

What? By 1888 Sprague's Richmond installation was already running. An amateur named John C. Henry used overhead copper cable to power his experimental car in 1884. And overhead wire was neither the first development, nor the critical one, in developing electric railways.

Woods' invention

For those curious, Woods' invention was not of the use of overhead wire for powering electric railways, but of an improved wire carriage (or "troller" or "traveller" designed to ride on top of a wire. These had previously been in use by other inventors, but Woods' invention was of an improved type with three wheels on a single wire and flanges, all apparently to address the problem that trollers had in falling off the wire. He did not submit a model, so I don't know that his design was ever tested.

The upshot is, that once sprung trolley poles were successfully deployed, all trollers became obsolete. -- Cecropia | explains it all ® 18:07, 25 Feb 2005 (UTC)

I am still new in this electrical knowledge, but somehow can someone tell me the differences between LRT and trams?

LRT and Trams.

I am still new in this electrical knowledge. But can someone tell me the differences between LRT and Trams?

Power Grids

please somebody help me out ....regarding what is proper functioning of power grids in india/US?

could somebody explain me about the ring main units working and about the construction of Ring main units..

Ajay Bhargove NDPL

Merged

• Overhead line, Overhead catenary, and Overhead cable are very similar (but not the same). These three articles should be reshuffled/reorganized/merged ito some sensible configuration. --Smack (talk) 17:29, 27 August 2005 (UTC)

Agreed

Its a little confusing to have three seperate articles about similar subjects. Why not have one article with three seperate sections? Piercetp 06:45, 25 May 2006 (UTC)

Merged

Merged as requested. SilkTork 22:09, 29 May 2006 (UTC)

Both Diagrams?

Do we really need both of these diagrams? They seem both the same to me. I am removing the first one, if you disagree, please revert without warning on my talk. I won't dispute this.martianlostinspace 14:06, 21 December 2006 (UTC)

Germany

It seems there are mixed up together "supply-lines" and the otherwise built "traction current lines". There are for example no "four lines on the lowest crossbar" of a "traction current line". The supply current lines have 110 kV power, the traction current lines is transformed down to 15 kV power. I live in Germany and I have never seen "eight conductor cables" on "traction supply lines". Regular are two lines for 110 kV supply and one line for direct supply of the traction line. The other bzw. feedback-"wire" then is the earth. Better kill the whole section "Germany"- it`s mostly wrong! 62.109.75.136 08:28, 1 February 2007 (UTC)

Why is 16.7 Hz used in Germany?LorenzoB 18:37, 7 April 2007 (UTC)

The reason for the frequency is apparently a Legacy from before the days of Power Electronics. One can allegedly practically operate a DC motor directly from this frequency but not 50 Hz.

86.18.84.41 20:48, 10 April 2007 (UTC)

Exactly correct. In the US, we got by with 25 Hz for the same reason. The basic problem is the inductive reactance of the traction motors.

Atlant 22:31, 10 April 2007 (UTC)

Im not sure if this is the correct place, but...

How come that when i cross a railway line, by means of a level crossing/one of those little paths that you use to cross the line with the STOP LOOK LISTEN sign in the UK, i dont get electrocuted? ACBestMy ContributionsAutograph Book 15:50, 21 June 2007 (UTC)

Back home, in Kent, the third rail has a dead section through the the level crossing (being foot path of cars, etc). This creates a gap, but normally Train are either a) long enough (think of a set of EMUs) to have more than one pick up show to collect the juice, and/or b) the train is going quick enough to cope with the loss of power (think of loco hauled trains). On OLE there is no gap, but a height limit to stop the high vehicles from electrocuting themselves. Hope that helps. Pickle 16:12, 28 June 2007 (UTC)

The conductor rails stop either side of the crossing, but are connected by cables to provide continuity for the electric current. Normally, there would also be "cow-boards" either side of the crossing to prevent people from trespassing. Canterberry 18:37, 28 June 2007 (UTC)

In the case of lines fed by an overhead wire (For example, throughout most of East Anglia), the overhead wire is the equivalent of the "Live" wire in a standard three pin plug, with the rails providing the "Neutral" connection. In the UK, the neutral connection is tied to earth (so the voltage between the ground and the rails is zero, and you don't get electrocuted). It's a different story if you were to look at the voltage across the overhead wire and the rails/ground, however... -- Ratarsed 13:05, 2 July 2007 (UTC)

Cost and Benefits

For heavy rail systems currently using diesels, I'm curious what the costs and benefits are of switching to overhead lines, both on tracks that don't yet have the overhead lines (is there some benefit to the proposed MBTA Indigo Line's use of DMUs, rather than putting in overhead lines and using EMUs?), and on tracks that have overhead lines but use diesels anyway (such as the MBTA train to Providence, which normally operates along the same track where Amtrak trains use the overhead lines). JNW2 14:54, 5 September 2007 (UTC)

It gets very complicated and contentious. Some people point to how is the user charged for the electricity they use. There are a lot of capital costs in building electrification (be it OLE or third rail) that put people off, especially for new lines. Also diesels (locos and especially DMUs) have made a lot of technical advances that make them more attractive. There are then system wide issues, so some operators may not like having to support tow types of fleets when they perceive fleet wide standardisation as preferable. Hope that gives you some pointers. Pickle 19:06, 5 September 2007 (UTC)

Height and other mechanical standards

It would be interesting to know the distance between the wire and the ground, and if there are different standards (including trams). Dvortex 14:55, 14 September 2007 (UTC)

I *think* they are built to the height gauge of the rail network concerned, and then the gap for the pantograph. I know the Channel Tunnel has higher wires than normal lines and the CTRL as the shuttle stock is higher (to take ro-ro trucks) - thus eurostars's pantograph has to go higher. Pickle 15:42, 14 September 2007 (UTC)

In the UK, on heavy rail (gauge just under 4 m) the height can vary between 4.14 m and 5.94 m, with a nominal height between 4.7 m and 4.9 m. CTRL uses a 'European' gauge so the minimum height is more like 5 m.Azmo247 22:04, 13 November 2007 (UTC)