OHLE 25kV or 750V DC third-rail

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Tom

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OHLE is more widespread though... mind you, OHLE, you can get within 5m and get shocked, with 3rd rail, you only touch it and shocked.
 

bunnahabhain

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OHLE, it allows faster speeds and is more widespread, which means it's cheaper to get components, and trains can easily interchange provided the voltages are not different.
 

Nick

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My thoughts are varied, in some ways I beleive in order to in some peoples opinion 'improve' our rail network with electrification a lot of it could be done fairly cheap on 3rd rail. Since only another rail is needed and only 750v is needed as constant power as opposed to 25,000 volts (aka. 25kv)

The automated currtent system in OHLE does though despite many peoples concerns make it safer as also it is placed higer compared to human level. Where as 3rd rail is foot/leg level and is direct current. Probably a reason why no new 3rd rail lines are allowed. An interesting fact not many know is that most tram systems use DC overhead systems at 750v because it is far easier for regenerative and rheostatic braking and more current is avalible for start/stop/start as on most trams.

I'm not fully convinced on one or the other at present..
Bring back steam!
 

tramboy

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Just thought i'd throw in an example of what other countries think of 3rd rail...when Siemens began to build Desiros for the southern area, they had to install the test track at Wildenrath with a third rail. Now, instead of doing it as we in Britain do (big metal uncovered rail at side of track), they put down the conductor rail, and covered the three sides that didn't need to be exposed in yellow plastic material...so you know that it was electric. Didn't prevent one person from being electrified by it though.

I voted OHLE...mainly because it is more flexible (ie railways and tramways)...and before someone points out that APS is being used in Bordeaux, take a look at the reliability figures for the APS system...most of the time it's non-functioning (keeps tripping cicuit breakers) and the trams have to use battery power. OHLE is also a lot safer in that its in the air, rather than on the ground! Current changes and more power can be drawn from it ( i read that somewhere)...and the magnificent class 92s (woefully underused) can run to nearly full capability on it!

Regards

Dave
 

Met Driver

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IMO both are equally dangerous (and equally safe) so I didn't consider safety to be an important factor.

I voted for the 25Kv system, due to the high operating speeds that it permits.
 
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Tom

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Correct. Most trains are limited to 100mph, but that's only a running speed of that unit. Non-tilters are generally limited to 100mph, except the HST... tilters (using 3rd rail) could use 126mph as a top speed.
 

Nick

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Interesting, but I do remember being told on the Southern region most trains were limited to 90mph I presume becuase of the strain on the current per section of each train?
 
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Tom

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Correct.

I can tell you on the Bournemouth line, the majority are 100mph runs.

Power problems between Bournemouth - Poole though due to Bournemouth TCRSMD (is that the correct initials?!)... only 2 10-WES or 1 444 Desiro - it can hold 3 450 Desiro's though.
 

TheSlash

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This is getting pathetic "Oh 3rd rail is dangerous because its on the floor"
If you are going to trip over 3rd rail, it will involve tripping over a running rail aswell.
The laws of electricity say you must be in contact with the power supply {3rd rail / OHLE} and also in contact with a earthed source, in order to get an electric shock.
I've made my feelings about the 'juice rail' known to my colleagues on the p-way, including what i will and will not do with it. As per usual they all do various things with it to 'prove me wrong' but at the end of the day, working on the electrical side of a 400 series EMU, in a maintenance depot, i know more than average what that juice rail can do and so i stick within the safe limits.
Just a few things to consider. 3rd has emergency isolation proceedures in the form of a short circuiting bar and lesser used hook switch pole. If someone is clinging to the juice rail, you can 'boot' them off it.
You can safely step over 3rd rail but its not recommended to go within 9 feet of OHLE, so which is more dangerous?
 

Craig

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TheSlash said:
If you are going to trip over 3rd rail, it will involve tripping over a running rail aswell.
There wouldn't be much risk of being electrocuted if you just tripped over a running rail though...
 

Met Driver

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Craig said:
TheSlash said:
If you are going to trip over 3rd rail, it will involve tripping over a running rail aswell.
There wouldn't be much risk of being electrocuted if you just tripped over a running rail though...
It's when you touch the running & conductor rails at once that you want to be worried :shock: .

Running rails have pretty much no electricity in them at all - only a few volts to operate the track circuits.
 

Met Driver

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joea1 said:
In my opinion, they are only dangerous if you touch or deliberately go near them. You can't get a shock if you don't. So stay well clear.
Indeed. What people often don't realise is that Electricity arcs, so you're at risk of being electricuted whether or not you're actually touching the conductor. It's best to keep a few feet away.
 

Max

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I prefer OHLE, as it permits higher running speeds, and corresponds better with the rest of Europe (which mainly uses OHLE)
 

Jordy

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laverack222 said:
I prefer OHLE, as it permits higher running speeds, and corresponds better with the rest of Europe (which mainly uses OHLE)
True, with OHLE the possibility of through trains to europe remains

Jordy
 

Met Driver

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Jordy said:
laverack222 said:
I prefer OHLE, as it permits higher running speeds, and corresponds better with the rest of Europe (which mainly uses OHLE)
True, with OHLE the possibility of through trains to europe remains
That's actually more difficult than you think. We use a slightly different system to the european network. I think it has something to do with pantograph height/tension.
 

Jordy

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Seth said:
That's actually more difficult than you think. We use a slightly different system to the european network. I think it has something to do with pantograph height/tension.
Yeah I remember that from the Eurostar Drivers Eye View video

Jordy
 

tramboy

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I think its cos we've always used a different type of pan to the french...their GPU design is compared with our Brecknell-Willis design. It's also cos French overhead takes a different pan tension to ours (i can't remember whether it is higher or lower).

Cheers

Dave
 
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