Manchester - Liverpool Electrification

[deltic08]

Think the lack of wiring is down to the lack of thing to hang it off. They have maybe learnt a lesson from Phase 1 where several runs had to be redone due to twisting of the wire caused my missing masts and cantalevers.

Also once the wiring trains get going it doesn't take long to string it up. Have aloso heard that they are doing it in a more methodical way this time, i.e earth and ATF/RC first then catenary and contact.

A few weeks overrun is neither here not there overall especially if civils on the other two sections are behind schedule preventing OHLE installation straight after phase 2

 

[Class377/5]

Where is the urgency with only two 319s available before Xmas

Reports are 3x 319 by Monday. Plan is for 4 units to have reached Northwern by December.

 

[LDECRexile]

As I've said before, if there are supports close to the ends of the A580 bridge, I think no support will be required on the bridge.

From Google satellite view the motorway bridges appear to be about 70m, 90m and 100m respectively, so I think all will require a support on the bridge, two for the M6 bridge.

Agreed.

There are supports close to the ends of the A580 bridge, making it my least concerning gap.
--- old post above --- --- new post below ---

Think the lack of wiring is down to the lack of thing to hang it off. They have maybe learnt a lesson from Phase 1 where several runs had to be redone due to twisting of the wire caused my missing masts and cantalevers.

Also once the wiring trains get going it doesn't take long to string it up. Have aloso heard that they are doing it in a more methodical way this time, i.e earth and ATF/RC first then catenary and contact.

Could you please say what "ATF/RC" stands for and what their jobs are?

 

[deltic08]

Reports are 3x 319 by Monday. Plan is for 4 units to have reached Northwern by December.

Must be a recent change then as only a few weeks ago Northern were saying only two 319s at timetable change in December 2014.

 

[Class377/5]

Must be a recent change then as only a few weeks ago Northern were saying only two 319s at timetable change in December 2014.

No they have stated only two in service. Plan has always been four units by December. Should work as two in service, one as spare and one for training. Sensible plan.

 

[snowball]

Could you please say what "ATF/RC" stands for and what their jobs are?

Just guessing, but maybe autotransformer feed and return conductor. The former exists in areas where the 50kV autotransformer system exists (Chat Moss line??) and the latter in other areas (Wigan line??).

 

[deltic08]

Agreed.

There are supports close to the ends of the A580 bridge, making it my least concerning gap.
--- old post above --- --- new post below ---


Could you please say what "ATF/RC" stands for and what their jobs are?

I think it mean automated transformers and return cable but happy to be corrected

 

[snowball]

I think it mean automated transformers and return cable but happy to be corrected

I think the auto- prefix in autotransformer means "self" rather than "automated", as autotransformers have a single winding.

Of course the auto- prefix in "automated" and "automatic" comes ultimately from the same meaning.

 

[deltic08]

No they have stated only two in service. Plan has always been four units by December. Should work as two in service, one as spare and one for training. Sensible plan.

Any news of 362? Number 3 is due off lease on Friday and I assume will go to Wolverton also.

 

[LNW-GW Joint]

Just guessing, but maybe autotransformer feed and return conductor. The former exists in areas where the 50kV autotransformer system exists (Chat Moss line??) and the latter in other areas (Wigan line??).

Return conductors are on all lines (both sides?).
Autotransformer feed is only on the main Chat Moss route and uses only one cable, usually high above the others.

 

[snowball]

Return conductors are on all lines (both sides?).

In that case I'm confused about the relationship, in autotransformer areas, between the return conductor, the rails and the autotransformers.

If the rails are connected to the centre tap of each autotransformer, are the return wires also connected to it? So why have a return wire in addition to the rails?

 

[DJH1971]

Reports are 3x 319 by Monday.

Where did you hear this?

I wonder if 319362 is among then?

 

[Class 170101]

I appear to be in a minority of one (unless you count Network Rail, which would make us two) in thinking we're still "on" for December.

Given the shambles of overruns this morning in Anglia and an emergency possession tonight to fix the mess at Ipswich I hope you can understand why. They overran two weeks ago in the same area as well.

12. M6 Viaduct

Is this viaduct anywhere near here? Perhaps more than more one worksite in the same area?
http://www.bbc.co.uk/news/uk-england-stoke-staffordshire-28942044

 

[LNW-GW Joint]

Is this viaduct anywhere near here? Perhaps more than more one worksite in the same area?
http://www.bbc.co.uk/news/uk-england-stoke-staffordshire-28942044

No, that's in "Staffordshire" and the gantries relate to the M6 Smart Motorway scheme (variable speed signs etc).
We are talking about a railway bridge over the M6 at Bryn/Ashton-in-Makerfield near Wigan, and rail electrification gantries.

 

[LDECRexile]

Given the shambles of overruns this morning in Anglia and an emergency possession tonight to fix the mess at Ipswich I hope you can understand why. They overran two weeks ago in the same area as well.


Is this viaduct anywhere near here? Perhaps more than more one worksite in the same area?
http://www.bbc.co.uk/news/uk-england-stoke-staffordshire-28942044

As LNWR-GWR Joint says - near Wigan.

Specifically, here:

http://www.bing.com/maps/#Y3A9NTMuN...mZW89MCZxPTUzLjQ5NTY0OCUyQyUyMC0yLjY1NzIyNg==

 

[Class377/5]

Where did you hear this?

I wonder if 319362 is among then?

Any news of 362? Number 3 is due off lease on Friday and I assume will go to Wolverton also.

Report is grab a unit from Bedford, head to Wolverton to pick up 362 and then take 8 cars north.

 

[DJH1971]

Report is grab a unit from Bedford, head to Wolverton to pick up 362 and then take 8 cars north.

Two for the price of one then!

 

[Class377/5]

Two for the price of one then!

And enough units for December plans. Just refreshing and training required now.

I'd guess that we'll see the first runs of a 319 under its own power in the NW during September.

 

[steverailer]

I think it mean automated transformers and return cable but happy to be corrected

Correct
--- old post above --- --- new post below ---

In that case I'm confused about the relationship, in autotransformer areas, between the return conductor, the rails and the autotransformers.

If the rails are connected to the centre tap of each autotransformer, are the return wires also connected to it? So why have a return wire in addition to the rails?

You don't have return conductor(rc) on a auto transformer system (atf), the extra wire on the side of the masts is an arieal earth. The main difference between the 2 system to tell them apart is the size of the insulator pots. RC pots are small single dish and usually bolted to the back of the mast/boom. The ATF one are 5/6 dish and mounted higher up on poles or dangling above high above the cantenary. The earth has no insulator and is bolted direct to the mast.

I'm still trying to get my head round how the ATF system works, even a trainer on a recent lineman course wasn't too sure. All I know is the ATF system alows more trains/electrical section than a RC system

 

[HSTEd]

In essence it is a 25kV circuit with a 25-0-25kV (basically 50kV) split phase circuit super imposed on it. Every autotransformer acts as a supply point where the 25kV current becomes half as much current at what amounts to 50kV. This traps electrical noise away from signalling gear and reduces resistive losses.

 

[snowball]

I think it mean automated transformers and return cable but happy to be corrected

Correct

Not quite, as I said above. AT stands for "autotransformer", but the "auto" in "autotransformer" is not short for automated or automatic.

 

[swt_passenger]

Not quite, as I said above. AT stands for "autotransformer", but the "auto" in "autotransformer" is not short for automated or automatic.

The use of 'auto' in autotransformer is in the sense of 'self' or 'single' referring to the number of windings.

 

[snowball]

If the thing that looks like a return wire in autotransformer areas is an aerial earth, why does it need to by insulated (even by single-shed insulators) from the masts, which are themselves surely earthed?

It would be nice if there was an explanation of the autotransformer system on the web that's at a sufficient level of detail to explain such questions, whilst still being accessible to non-experts.

--- old post above --- --- new post below ---

The use of 'auto' in autotransformer is in the sense of 'self' or 'single' referring to the number of windings.

As in autobiography, autonomy, autosuggestion, automobile, auto-immune, etc.

 

[LNW-GW Joint]

The autotransformer system for Phase 1 is still not commissioned.
The switchgear which has recently gone in at Astley and Huyton Quarry is part of the overall scheme.
I imagine the whole of the Chat Moss route will be commissioned at the end of the year.
It is not being fitted to Huyton-Wigan, so my guess is that autotransformers will also go on the Euxton Jn-Manchester-Leeds-York route as well but probably not on Preston-Blackpool or Lostock-Wigan or other branches.
There is similar work going on on the WCML between Crewe and Cumbria, with some kit recently installed just north of Springs Branch Jn.

 

[edwin_m]

If the thing that looks like a return wire in autotransformer areas is an aerial earth, why does it need to by insulated (even by single-shed insulators) from the masts, which are themselves surely earthed?

I think this is to ensure that the current in the wire stays in the wire, rather than wandering off down the poles, through the earth and back up another pole. This reduces the touch potentials between objects that are nominally earthed.

 

[HSTEd]

If the thing that looks like a return wire in autotransformer areas is an aerial earth, why does it need to by insulated (even by single-shed insulators) from the masts, which are themselves surely earthed?

Well its easier to start from the beginning - there are three basic types of 25kV installations - rail return, booster transformer and autotransformer.

Rail return is the simplest - it simply has the live 25kV conductor and attaches the earth at the substation to the rails. This means current flows through the conductors and back through the rails.
This unfortunately causes interference with track circuits and coupling to the signalling cables.

Next we have booster transformers - this is a rail return system but with an additional 'return conductor'. Booster transformers are positioned along the system and use the traction current in the main conductor to drive the return conductor to a non zero voltage 180 degrees out of phase with the main one.
This makes the rail return current flow to the nearest booster transformer and then through the return conductor - reducing coupling to signalling system.
The insulation is required because the return conductor is at ~500Vrms.

Autotransformers - this is the rail return system but instead of a low voltage return conductor has an autotransformer (essentially a centre tapped transformer coil that isg rounded in the middle and attached at one end to the main conductors) that couples the 25kV circuit to the -25kV circuit that flows through the second conductor.
As this conductor is at 25kV (-25kV in this context means it is 25kV and 180 degree out of phase) it requires a full set of insulators.
This means a current (Say 100A for example) flows through the main conductor and the rails to the nearest autotransformers - at which point superimposed 50A currents flow from the autotransformer to the substation through the main and antiphase conductor.
This reduces coupling to the signalling system like booster transformers but also drastically reduces resistive losses, especially in high power installations.

 

[DJH1971]

And enough units for December plans. Just refreshing and training required now.

I'd guess that we'll see the first runs of a 319 under its own power in the NW during September.

Probably between Liverpool to Crewe, Crewe to Preston and Manchester to Crewe until Earlestown to Wavetree is wired.

 

[AM9]

Well its easier to start from the beginning - there are three basic types of 25kV installations - rail return, booster transformer and autotransformer.

Rail return is the simplest - it simply has the live 25kV conductor and attaches the earth at the substation to the rails. This means current flows through the conductors and back through the rails.
This unfortunately causes interference with track circuits and coupling to the signalling cables.

Next we have booster transformers - this is a rail return system but with an additional 'return conductor'. Booster transformers are positioned along the system and use the traction current in the main conductor to drive the return conductor to a non zero voltage 180 degrees out of phase with the main one.
This makes the rail return current flow to the nearest booster transformer and then through the return conductor - reducing coupling to signalling system.
The insulation is required because the return conductor is at ~500Vrms.

Autotransformers - this is the rail return system but instead of a low voltage return conductor has an autotransformer (essentially a centre tapped transformer coil that isg rounded in the middle and attached at one end to the main conductors) that couples the 25kV circuit to the -25kV circuit that flows through the second conductor.
As this conductor is at 25kV (-25kV in this context means it is 25kV and 180 degree out of phase) it requires a full set of insulators.
This means a current (Say 100A for example) flows through the main conductor and the rails to the nearest autotransformers - at which point superimposed 50A currents flow from the autotransformer to the substation through the main and antiphase conductor.
This reduces coupling to the signalling system like booster transformers but also drastically reduces resistive losses, especially in high power installations.

Also, by routing it reasonably close to the contact wire, the antiphase wire behaves more like a balanced transmission line which reduces the EMI coupling to other lower voltage circuits such as signals/telecomms and non-railway infrastructure outside the NR boundaries.

 

[snowball]

Well its easier to start from the beginning - there are three basic types of 25kV installations - rail return, booster transformer and autotransformer.

Rail return is the simplest - it simply has the live 25kV conductor and attaches the earth at the substation to the rails. This means current flows through the conductors and back through the rails.
This unfortunately causes interference with track circuits and coupling to the signalling cables.

Next we have booster transformers - this is a rail return system but with an additional 'return conductor'. Booster transformers are positioned along the system and use the traction current in the main conductor to drive the return conductor to a non zero voltage 180 degrees out of phase with the main one.
This makes the rail return current flow to the nearest booster transformer and then through the return conductor - reducing coupling to signalling system.
The insulation is required because the return conductor is at ~500Vrms.

Autotransformers - this is the rail return system but instead of a low voltage return conductor has an autotransformer (essentially a centre tapped transformer coil that isg rounded in the middle and attached at one end to the main conductors) that couples the 25kV circuit to the -25kV circuit that flows through the second conductor.
As this conductor is at 25kV (-25kV in this context means it is 25kV and 180 degree out of phase) it requires a full set of insulators.
This means a current (Say 100A for example) flows through the main conductor and the rails to the nearest autotransformers - at which point superimposed 50A currents flow from the autotransformer to the substation through the main and antiphase conductor.
This reduces coupling to the signalling system like booster transformers but also drastically reduces resistive losses, especially in high power installations.

Thank you but I already understood that. My questions were specifically about the role, in autotransformer areas, of the conductor that is at a relatively low voltage relative to the rails, and is hung on small insulators off the masts. In other words it exists in autotransformer areas but it looks just like the return conductor that exists in booster transformer areas. Edwin M has given the best reply though I'm not sure I understand fully. I gather that this conductor and the rails are both connected to the centre tap of each autotransformer.

 

[HSTEd]

Ah - that is odd, but I think it might be an attempt to prevent some very nasty fault conditions inherent to autotransformers.... I will do some checking along that line.