Guide to overhead electrification

[najaB]

This might be a well-known document, but I just came across it so thought I'd share. An extract from the introduction:

Overhead Line Equipment – or OLE – is the name railway engineers give to the assembly of masts, gantries and wires found along electrified railways.

All this steel and cable has only one purpose – to supply power to make electric trains move.

Operationally, environmentally and from the perspective of passenger service and comfort, OLE is now the preferred means of powering trains throughout the world. For example, when the High Speed line from St Pancras to Paris was built, there was only one choice for the engineers: OLE.

But there is no doubt that it can be visually intrusive, and installing it on existing lines can require alterations to bridges, stations and other structures.

OLE is also undeniably complex and frankly baffling to the lay person.
The purpose of this guide, therefore, is to help all those with an interest in the current Network Rail electrification projects – whatever that interest may be – to understand why the line is being electrified, and why some changes to existing structures are required. It has been produced by Alan Baxter & Associates on behalf of Network Rail with information supplied by, and with the assistance of, a number of the company’s engineers. Its contents have been reviewed and signed-off by Network Rail.

The document has been written for the non-specialist, not the expert, and explains with the aid of diagrams how OLE works and why it has to look the way it does.

Link to document.

 

[J-2739]

Thanks for posting. Been meaning to look for something like this before! Will educate myself on this as electrical engineering seems to be a potential career path for me!

I must be the only one who prefers the look of OHLE compared to third rail, like the mechanical look and the thought of 25kv electricity is music to my ears!

Hopefully, the Hallam line gets the wires soon!

 

[edwin_m]

the thought of 25kv electricity is music to my ears!

Off topic, but many years ago I organised some tests which involved pumping current at various frequencies through the overhead of Croydon Tramlink to see how much of it appeared in nearby heavy rail track. This required a signal generator the size of a fridge, and we could have played quite a nice tune on it if we'd had the time.

 

[DaveNewcastle]

Off topic, but many years ago I organised some tests which involved pumping current at various frequencies through the overhead of Croydon Tramlink to see how much of it appeared in nearby heavy rail track. This required a signal generator the size of a fridge, and we could have played quite a nice tune on it if we'd had the time.

What did the test use as a load bank? Not a clutch of trams, I hope!

 

[GRALISTAIR]

Thanks for posting. Been meaning to look for something like this before! Will educate myself on this as electrical engineering seems to be a potential career path for me!

I must be the only one who prefers the look of OHLE compared to third rail, like the mechanical look and the thought of 25kv electricity is music to my ears!

Hopefully, the Hallam line gets the wires soon!

Trust me you are not the only one. 25kV AC OHL any day please.

 

[edwin_m]

What did the test use as a load bank? Not a clutch of trams, I hope!

No load bank involved. The OLE was "earthed" to the rails at one end of the section and we connected the signal generator between the two at the other. The voltage on the signal generator was wound up enough to generate a current of a few amps, limited by the circuit impedance.

Back on topic, the linked document claims that "long" neutral sections switch themselves from one supply to the other as the train passes through, so as to maintain continuous supply to the train. I've never heard of this happening and am 99% sure it is an error.

 

[najaB]

Back on topic, the linked document claims that "long" neutral sections switch themselves from one supply to the other as the train passes through, so as to maintain continuous supply to the train. I've never heard of this happening and am 99% sure it is an error.

It's the first time I've heard it too so was surprised, but they say that NR read and approved the content. Maybe it is something that is possible but not often implemented. Perhaps the only examples are on HS1?

 

[LNW-GW Joint]

The document reads well and is a good primer.
But it does emphasise ATF as the normal OHLE installation, which I don't think is yet the case.
In the NW scheme, Liverpool-Manchester has ATF, but Huyton-Wigan does not.
In Scotland, from what I could see in the spring, there is no ATF on the EGIP route (the clue during construction is the height of lineside masts, then the arms and insulators).
So there must be different criteria for designing these systems, as opposed to the GWML.
I thought ATF systems meant "more power", whereas the document suggests it means "fewer booster transformers" and lineside kit.

In some ways the document is a more detailed version of what NR put in its 2009 Electrification RUS, whose update has been awaited for some years now (always "next year").
Maybe when it does appear, NR will dispense with the background description and refer people to this document.