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Post by bassmike on Jun 11, 2017 11:34:10 GMT
Correct me if I'm wrong but I thought the two northern tracks were disused before the picc: appeared.
EDIT:
Duplicate posts removed
Domk
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Dom K
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Post by Dom K on Jun 11, 2017 12:02:39 GMT
Can you please use thread options to edit and/or delete posts instead of using posts as corrections. If you need guidance PM a staff member who will help you
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Post by spsmiler on Jun 11, 2017 21:38:40 GMT
Correct me if I'm wrong but I thought the two northern tracks were disused before the picc: appeared. Thats what I thought too! Simon |
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Post by t697 on Jun 12, 2017 6:50:54 GMT
The South Kensington-Victoria and Moorgate-Aldgate/Aldgate East sections seem odd omissions. Is the there a reason for this or are they just not yet scheduled? No they are scheduled in the same time frame. So easy to miss bits from a list isn't it! |
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Post by t697 on Jun 12, 2017 6:58:07 GMT
Finchley Road to Harrow is also missing. Jubilee and Met trains use the same tracks in and out of Neasden Depot. So it's not practicable to keep their electrical supplies entirely segregated. Therefore Finchley Road to Harrow, which is all one electrical section, stays at nominal 630V supply but S stock regenerates to 790V in that stretch and has done since about 2014 if I recall correctly. 1996TS on the Jubilee also does 790V regenerative braking, but isn't rated for 890V. |
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Deleted
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Post by Deleted on Jun 12, 2017 13:19:54 GMT
Therefore Finchley Road to Harrow, which is all one electrical section, I thought there was a sub gap on the approach to Preston Road? |
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Post by Deleted on Jun 12, 2017 14:48:49 GMT
There is Preston Road to Wembley Park one way and Preston Road to Harrow On The Hill the other
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Post by t697 on Jun 12, 2017 17:59:29 GMT
Therefore Finchley Road to Harrow, which is all one electrical section, I thought there was a sub gap on the approach to Preston Road? There is a sub-station gap at Preston Road Sub-Station, but it's not a Sectionalisation gap. Not all sub-stations are at Sectionalisation boundaries. Indeed there are other sub-stations between Harrow and Finchley Road. |
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Post by d7666 on Oct 12, 2017 18:54:29 GMT
As I understand things, the entire Circle line goes to 750 V during work this week and next week, including west to Barons Court, north west to Finchley Road, Royal Oak, and Olympia (ie all of Earls Court area included).
East of Victoria and east of Moorgate (all of Aldgate triangle included) have been 750 V for some months now, right to Upminster, so thats how the Circle is completed.
Harrow / Amersham / Chesham / Watford, and Royal Oak to Hammersmith already done.
I think I'm right this leaves a gap Finchley Road to Harrow which (and this is a question not a statement) is more connected with 1996 stock limitations than anything else?
--
Nick
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Post by t697 on Oct 12, 2017 19:14:21 GMT
Yes that's right. And as per further up this thread, 1996TS on the Jubilee also does 790V regenerative braking, but some components aren't rated for 890V.
If the supply voltage were put up to nominal 750V, the regen benefit is reduced if the limit stays 790V.
For that area it is more efficient to keep the nominal 630V supply, with 790V Regen.
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Post by gals on Oct 12, 2017 21:16:09 GMT
Could someone explain why the voltage is being increased and what benefits that has? Thanks.
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Deleted
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Post by Deleted on Oct 12, 2017 21:25:09 GMT
Better performance once the signalling upgrade has finally happened
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Post by phil on Oct 12, 2017 21:33:41 GMT
Could someone explain why the voltage is being increased and what benefits that has? Thanks. Ohms law Power is defined as the Voltage between each leg multiplied by the Current flowing through the circuit. If you increase the voltage then the current required to generate the same Power is reduced. The more current that flows, the bigger the cables have to be - otherwise they will overheat due to their resistance. This is why in railway and electrical distribution terms voltages have been increased whenever possible. |
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Post by norbitonflyer on Oct 12, 2017 22:08:24 GMT
Ohms law Power is defined as the Voltage between each leg multiplied by the Current flowing through the circuit. If you increase the voltage then the current required to generate the same Power is reduced. It also follows that energy lost in the cables/ live rails (and therefore not available to drive trains) is I^2 R (or R/ V^2) Given that R is fixed (as it depends on the rail's length and cross sectional area, and the material the rail is made of), increasing the voltage by about 40% halves the losses in the electricity feed. This also explains why voltage falls off with distance from the substation, and why the substations need to be closer together in low voltage systems. |
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Chris M
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Post by Chris M on Oct 12, 2017 22:28:24 GMT
If you aren't familiar with the formula, I = current, R = resistance and V = voltage.
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Post by Dstock7080 on Oct 19, 2017 9:26:27 GMT
The 750v Sub-surface upgrade has now been completed, all sections;
- Upminster - Putney Bridge/Barons Court/Olympia
- Hammersmith/Finchley Road - Tower Hill/Aldgate East
- Amersham/Chesham/Watford - Harrow.
sections not being done;
- Uxbridge - Harrow (remains at 630v nominal and regen at 650v)
- Harrow - Finchley Road (remains at 630v but regen available at 790v)
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cso
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Post by cso on Oct 19, 2017 12:43:17 GMT
I assume the sections missing are because of inter-stock working?
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Post by d7666 on Oct 19, 2017 12:52:37 GMT
The 750v Sub-surface upgrade has now been completed, all sections; - Upminster - Putney Bridge/Barons Court/Olympia - Hammersmith/Finchley Road - Tower Hill/Aldgate East - Amersham/Chesham/Watford - Harrow. sections not being done; - Uxbridge - Harrow (remains at 630v nominal and regen at 650v) - Harrow - Finchley Road (remains at 630v but regen available at 790v) Barons Court to Acton Lane and Ealing Broadway? I thought those SSL sections stayed 630 V? -- Nick |
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Post by Deleted on Oct 19, 2017 13:24:45 GMT
The 750v Sub-surface upgrade has now been completed, all sections; - Upminster - Putney Bridge/Barons Court/Olympia - Hammersmith/Finchley Road - Tower Hill/Aldgate East - Amersham/Chesham/Watford - Harrow. sections not being done; - Uxbridge - Harrow (remains at 630v nominal and regen at 650v) - Harrow - Finchley Road (remains at 630v but regen available at 790v) Barons Court to Acton Lane and Ealing Broadway? I thought those SSL sections stayed 630 V? -- Nick Correct they are staying at 630v |
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Post by MoreToJack on Oct 19, 2017 14:08:50 GMT
I assume the sections missing are because of inter-stock working? Yep. Bad Things happened when a 73TS got diverted over a section with higher regen, although it was never planned to up the voltage in the shared areas. The issue isn't so much with the equipment that runs at high voltage, but rather the lower voltage equipment contained on board. For example, the Track Recording Train requires mitigations with its catalytic convertor when travelling over areas with a higher voltage. |
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Post by Deleted on Oct 19, 2017 14:13:29 GMT
Didn’t know it started running on diesel
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Post by nickf on Oct 19, 2017 17:03:19 GMT
I assume the sections missing are because of inter-stock working? Yep. Bad Things happened when a 73TS got diverted over a section with higher regen, although it was never planned to up the voltage in the shared areas. The issue isn't so much with the equipment that runs at high voltage, but rather the lower voltage equipment contained on board. For example, the Track Recording Train requires mitigations with its catalytic convertor when travelling over areas with a higher voltage. Ah...I thought on first reading that it was Catholic Converter. No one expects the Spanish Inquisition. |
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cso
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Post by cso on Oct 19, 2017 18:38:09 GMT
Low voltage things definitely don’t tend to like having high voltage through them as the OH discovered when he put 240v through a 24v component.
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Post by superteacher on Oct 19, 2017 18:45:15 GMT
Low voltage things definitely don’t tend to like having high voltage through them as the OH discovered when he put 240v through a 24v component. You can get away with being a certain amount over, but 10 times over was probably terminal (pun intended!) |
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Post by d7666 on Oct 22, 2017 11:08:27 GMT
Barons Court to Acton Lane and Ealing Broadway? I thought those SSL sections stayed 630 V? -- Nick Correct they are staying at 630v Thanks for confirmation. -- Nick |
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