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Post by Deleted on Jun 13, 2017 19:47:56 GMT
Any news on the conversion project? I am wondering why did they use DC motors on the 1992 stock in the first place, when AC traction motors became widely available at a sensible price towards the end of the eighties?
They appear to have missed an oppoutunity around 1989/1990 to use AC traction from the beginning, instead of the unreliable DC traction, with motors that fell off in service (Chancery Lane in 2003 perhaps?).
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Post by fish7373 on Jun 13, 2017 20:15:44 GMT
The propulsion for the trains was manufactured by a consortium of ABB and Brush Traction,[2] and was one of the first examples of microprocessor-controlled traction featuring a fibre-optic network to connect the different control units. The DC traction motors of LT130 type have separately-excited fields and are controlled via GTO (Gate turn-off) thyristors Due to excessive carbon brush wear, the replacement of the DC motors was considered, but decided against. true what you say but bad maintenance for the motor falling off.
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Post by phil on Jun 17, 2017 21:57:21 GMT
Any news on the conversion project? I am wondering why did they use DC motors on the 1992 stock in the first place, when AC traction motors became widely available at a sensible price towards the end of the eighties? They appear to have missed an oppoutunity around 1989/1990 to use AC traction from the beginning, instead of the unreliable DC traction, with motors that fell off in service (Chancery Lane in 2003 perhaps?). AC traction motors were still a novel and largely untried method of propulsion in the early 1990s when the 92 stock was being designed and required far more sophisticated control systems to make them work than the tried and tested DC motors used hitherto. The first mainline trains to use them were the DC Networkers*, followed by the class 92s locos and original Eurostars - all of which had quite a few teething troubles getting them to work reliably. Given the high frequency service provided by the Underground sticking with tried and tested DC motors was probably due to LUL sticking with what they knew rather than be the test bed for new technology and all the pitfalls that entails. A few years down the line, improvements in the control gear, plus a grater understanding more generally by both manufacturers and those issuing tenders for new stock about the advantages of AC motors saw everything be fitted with AC motors. * Some of which have had their original troublesome AC motors and control gear replaced by Hitachi a few years ago with a marked improvement in fleet availability.
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Post by t697 on Jun 18, 2017 17:39:36 GMT
Also the signalling compatibilty case methodology for fixed frequecy DC choppers was becoming well understood with LU Signal Engineering at the time. It would have been a huge effort at the time to abandon that before a single full fleet introduction and get acceptance of the principle of variable voltage, variable frequency AC inverter drives accepted at that time. Fortunately, others had cracked that by the time the Jubilee line fleet was ordered and the acceptance door was ajar! Yes a pity in retrospect, another year or so and the Central line fleet could and possibly should have had three phase drives.
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Post by 100andthirty on Jun 18, 2017 18:28:59 GMT
It's also worth remembering that the first ac/three phase traction systems weren't always trouble free. The BREL Networkers with Brush traction eventually had the inverter package replaced by a Hitachi system which improved their reliability.
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Post by spsmiler on Jun 19, 2017 20:27:55 GMT
Will the trains sound different? If so, will *ordinary* passengers notice? (Transport enthusiasts are bound to notice - hence the emphasis on the word 'ordinary'!)
Simon
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Post by Deleted on Jun 20, 2017 17:59:34 GMT
A contractor has been selected for the re-tractioning project however the contract award has been held up because the tender adjudication process is being challenged in the high court by the contractor which was not selected.
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Post by Deleted on Jun 20, 2017 20:16:10 GMT
No more Gear Changing sounds of the GTO Thyristors used in trains of that era from approximately 1989 to 1996, whereby the train moving off generated a gear changing noise, especially noticeable on the networkers of that era.
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Post by drainrat on Jul 5, 2017 13:00:13 GMT
No more Gear Changing sounds of the GTO Thyristors used in trains of that era from approximately 1989 to 1996, whereby the train moving off generated a gear changing noise, especially noticeable on the networkers of that era. Gear changing sounds 🤔 You mean the clicking 🙄
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Post by drainrat on Jul 5, 2017 13:02:44 GMT
Any news on the conversion project? I am wondering why did they use DC motors on the 1992 stock in the first place, when AC traction motors became widely available at a sensible price towards the end of the eighties? They appear to have missed an oppoutunity around 1989/1990 to use AC traction from the beginning, instead of the unreliable DC traction, with motors that fell off in service (Chancery Lane in 2003 perhaps?). Perhaps what? Isn't that exactly what happened
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Post by norbitonflyer on Jul 5, 2017 13:22:10 GMT
No more Gear Changing sounds of the GTO Thyristors used in trains of that era from approximately 1989 to 1996, whereby the train moving off generated a gear changing noise, especially noticeable on the networkers of that era. Gear changing sounds 🤔 You mean the clicking 🙄 The way the motor pitch rises steadily and then drops suddenly, a cycle repeated three or four times in the first few seconds as it moves off, as heard on the 465/9 at the beginning of this clip. Sounds just like a mechanical transmission changing rapidly up through the gears. (Some 465 versions now have new traction packages which don't do this - the clip demonstrates the differnce) 1996 stock does it too, but I couldn't find a good recording of one.
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Post by drainrat on Jul 5, 2017 15:41:37 GMT
Ah yes, I see. My first experience of the noise was dwells at Baker st SB (when I was driving on Bakerloo line) and hearing the 96ts 'take off' from the adjacent platform, then I became a 96ts test track driver and didn't hear it until the extension broke through and we were able to drive under traction. Never experienced it on the 92ts both as a driver and a passenger when the stock first started appearing. The clicking I was thinking were the resistors dropping on 59/62 stocks as controller moved through shunt and series 😉
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Post by tunnelbore on Jul 5, 2017 19:51:13 GMT
Gear changing sounds 🤔 You mean the clicking 🙄 The way the motor pitch rises steadily and then drops suddenly, a cycle repeated three or four times in the first few seconds as it moves off, as heard on the 465/9 at the beginning of this clip. Sounds just like a mechanical transmission changing rapidly up through the gears. (Some 465 versions now have new traction packages which don't do this - the clip demonstrates the differnce) 1996 stock does it too, but I couldn't find a good recording of one. You maybe know this already but just in case: these drives used synchronous PWM (pulse width modulation) with the GTOs switching at given multiple of the AC frequency fed to the motor. For instance, 33 times faster than a 5Hz supply would give 165Hz switching that would be a note you could hear (you hear it because the lamination in the motor core vibrate slightly at that frequency). As the train accelerates and the AC frequency is increased to keep it accelerating, the GTO would switch faster and the note would rise. However, you can't let the GTOs switch too fast or they'll overheat so at say, 15Hz AC / 495 Hz switching, you'd then drop the ratio to 21 times and at the same 15 Hz AC produce a note at 315 Hz which would then go on rising until the next time you needed to drop the ratio. I don't know the rations and upper switching frequency limits for the drives in question so the numbers are for illustration only. This was known as Gear Changing PWM. More modern IGBT drives don't often need any of this. The IGBTs can switch fast and are held at a constant and quite high switching frequency. Class 377s are in this category I think. The class 700s make a rather strange warbling sound to my ear. I suspect they have something similar to gear changing PWM but with some additional modulation to mask the sound.
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Post by 100andthirty on Aug 25, 2017 19:57:36 GMT
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Post by Deleted on Aug 25, 2017 21:53:57 GMT
I read that differently. Awarded to supply control gear and motors, and fit/test the first train. I was under the impression it was work to be possibly done at TMU (LU) while the central line trains are there for the clip project.
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Post by 100andthirty on Aug 26, 2017 7:24:28 GMT
luacton......probably would have been better for me just to say the contract has been placed!
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Post by crusty54 on Aug 26, 2017 16:19:41 GMT
I read that differently. Awarded to supply control gear and motors, and fit/test the first train. I was under the impression it was work to be possibly done at TMU (LU) while the central line trains are there for the clip project. The press release clearly states the the first train will be be fitted out in Derby.
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Post by Deleted on Aug 27, 2017 7:36:26 GMT
I read that differently. Awarded to supply control gear and motors, and fit/test the first train. I was under the impression it was work to be possibly done at TMU (LU) while the central line trains are there for the clip project. The press release clearly states the the first train will be be fitted out in Derby. Thanks, but I understood that bit. I am just slightly confused about what work is due to be done where.
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Post by 100andthirty on Aug 27, 2017 18:57:16 GMT
Speculating aloud:
The plan which I'm sure I've seen something in TfL Board papers was to have the work done at Acton. The reason is that it is much easier to get the trains to and from Acton quite possibly under their own power leading to reduced time in transit. My estimate is that Acton saves at least 4 days per train compared with shipping the trains to Derby.
However, doing the work on the first train in Derby makes perfect sense. It will take a lot longer to fit out the first train; indeed, Bombardier might want access to a train whilst the detail design for the conversion is worked though. In this context the time taken for the journey is immaterial. BT can then practice the fitting job; make changes if necessary and have access to test facilities including RIDC Melton comparatively nearby. I would guess that the "first train" could be away for "a long time".
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Post by A60stock on Aug 27, 2017 19:40:46 GMT
Hi, apologies if i have missed this anywhere but does anyone know when the retraction programme as mentioned here will begin, with the first train in service? Will this be done in line with the other overhauls mentioned or will each part be separate?
By overhauls i am referring to the proper refurbishment of the trains, although i am not quite sure how you could improve the interior and exterior appearance of these trains
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Post by stapler on Aug 27, 2017 20:57:46 GMT
How could you improve the interiors? Just for starters Replace grab rails whose plastic coating is peeling Get some comfortable sprung seating as good as that on the Standard stock reinstitute the armrests Paint the interior surfaces of the doors, the ones you can see and the ones behind glass Replace the fan motors with ones that don't sound as if they'd power a BAC1-11
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Post by Dstock7080 on Aug 27, 2017 21:14:15 GMT
Hi, apologies if i have missed this anywhere but does anyone know when the retraction programme as mentioned here will begin, with the first train in service? Will this be done in line with the other overhauls mentioned or will each part be separate? The new workshop in Acton Works hasn't even started to be built yet, indeed the land required will only become vacant from 2 September, when the sidings are decommissioned. The idea is that the Central Line Upgrade Project will all be done within this new workshop, including the retractioning.
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Post by fish7373 on Aug 27, 2017 23:18:58 GMT
Hi, apologies if i have missed this anywhere but does anyone know when the retraction programme as mentioned here will begin, with the first train in service? Will this be done in line with the other overhauls mentioned or will each part be separate? The new workshop in Acton Works hasn't even started to be built yet, indeed the land required will only become vacant from 2 September, when the sidings are decommissioned. The idea is that the Central Line Upgrade Project will all be done within this new workshop, including the retractioning. Who has got the contract seems to be a lot of confusion on here so who has it ACTON or DERBY, www.globalrailnews.com/2017/08/25/new-traction-systems-for-lus-central-line/
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Post by MoreToJack on Aug 28, 2017 0:29:27 GMT
It's quite simple.
The first train will go to Derby and be fitted out in Bombardier's workshops. As explained by others, it makes perfect sense for the first train to be done in the contractor's workshops to ensure that any teething troubles are worked out. These are an inevitability, and will take more time than later fit outs.
Subsequent trains will be retractioned in the new CLIP shed at Acton Works, in conjunction with the other refurbishment works. It appears that Bombardier staff will still carry out the retraction, alongside LU staff carrying out the refurb.
Then again... this is the Underground. The shed hasn't even commenced build yet, and until the first/second/subsequent train(s) begins work I think we can accept that anything is possible.
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Post by Deleted on Aug 28, 2017 5:44:07 GMT
Speculating aloud: The reason is that it is much easier to get the trains to and from Acton quite possibly under their own power leading to reduced time in transit. The plan is for two units (half a train) at a time to be moved at a time using the MPU that was being built for the vacuum train a few years ago.
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Post by Deleted on Aug 28, 2017 9:53:31 GMT
Acton Works is easier - contingent on being able to get the new facility built in the first place.....
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metman
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Post by metman on Aug 29, 2017 12:24:56 GMT
The MPUs are a pair of 1972mk1 DMs right?
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a60
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Post by a60 on Aug 29, 2017 12:35:43 GMT
67ts I believe.
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Post by Deleted on Aug 29, 2017 20:47:12 GMT
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metman
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Post by metman on Aug 29, 2017 20:55:27 GMT
Thanks I assume with an MA and compressors in the saloon.
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