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Loss of Power

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Loss of Power 12/01/2021 at 17:20 #136297
tomkagnew
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Hi All

Just a couple of questions about this 'attribute':

Does LOP transfer over to subsequent workings in the same simulation?
Does LOP transfer across with rules like '2X01 must not enter until 6 minutes after 2X00 leaves' and 2X00 has loss of power, will 2X01 enter with it too?
Does LOP on a train remain in place after restarting a sim from a save?
Are there any other implications apart from reduced top speed and acceleration, such as increased technical stops?

Thanks to all
Tom

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Loss of Power 12/01/2021 at 17:29 #136299
Steamer
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In order asked:

Fairly sure Yes (Don't know what happens if it splits or joins)
No
Yes
Fairly sure No

"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
Last edited: 12/01/2021 at 17:31 by Steamer
Reason: None given

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Loss of Power 12/01/2021 at 17:53 #136300
jc92
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I'm not sure it does carry over to next workings. Maybe Geoff can confirm?

It sticks in my mind because of how silly the logic is, that the train instantly recovers.

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Loss of Power 12/01/2021 at 18:36 #136302
tomkagnew
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Thank you kindly chaps, this is all general curiosity but stemmed from this situation.

Had a train come in to the board during a multiplayer with LOP. Was able to do a set swap with a 'healthy' unit stabled at it's destination, with the sick unit stuck into the stabling siding (in real life probably being attended by fitters). During the multiplayer it was decided to return the unit to depot in exchange for a working one that afternoon. The session ended.

This afternoon I've been tidying up the save and finding a path for the new movement. Made the TT, and assigned the sick unit to 'run to timetable 5Z21'. But when tested, it ran with normal characteristics. I shut down and repeated but with the added step of checking the 'Loss Of Power' in F4 for 5Z21 before 'run to TT'. Still runs up to 90, the expected max speed for the train.

It's not the end of the world but just seeking to understand the workings of the program as much as I can, especially when it comes to contingency planning.

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Loss of Power 12/01/2021 at 18:53 #136304
Steamer
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jc92 in post 136300 said:
I'm not sure it does carry over to next workings. Maybe Geoff can confirm?

It sticks in my mind because of how silly the logic is, that the train instantly recovers.
Having just tested it, I think you're right.

"Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q)
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Loss of Power 12/01/2021 at 19:05 #136305
danners430
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I can confirm that it definitely does carry over onto subsequent workings, and throughout chained simulations. This became rather evident during Elliot's recent WCML chain, where we found a train with a LOP three sessions after it had first been reported...!
Last edited: 12/01/2021 at 19:09 by danners430
Reason: None given

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Loss of Power 12/01/2021 at 19:08 #136306
Class 92
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Could it possibly depend on the sim being used? I know on an Exeter session, the loss of power didn't carry over to the next working.
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Loss of Power 12/01/2021 at 19:24 #136307
tomkagnew
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danners430 in post 136305 said:
I can confirm that it definitely does carry over onto subsequent workings, and throughout chained simulations. This became rather evident during Elliot's recent WCML chain, where we found a train with a LOP three sessions after it had first been reported...!
Based on this Cl 442 example, the actual train and its defect appears to either not survived a) headcode change or b) a save!

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Loss of Power 12/01/2021 at 19:50 #136311
GeoffM
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Mantis #32795 for investigation later. First glance it looks like LOP survives some transitions but not others.
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Loss of Power 12/01/2021 at 20:17 #136320
tomkagnew
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GeoffM in post 136311 said:
Mantis #32795 for investigation later. First glance it looks like LOP survives some transitions but not others.
Would saves be of any use here Geoff? The original notification of loss of power on the initial problem-train (1D48, notified 0952) was after the penultimate save so not sure that it would.... Attached them anyway...

Tom

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Loss of Power 13/01/2021 at 09:12 #136332
kbarber
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GeoffM in post 136311 said:
Mantis #32795 for investigation later. First glance it looks like LOP survives some transitions but not others.
Which seems entirely prototypical. Sometimes the tapper will kick the right apparatus case in the right way and the train will miraculously recover (it's like the old joke about the plumber's bill). Other times the unit will drag its weary way back to the depot for a shift being gone over, a 'NFF' in the repair book, then promptly fall over as soon as it's let out again. And sometimes that's 'rinse and repeat' for several weeks until the depot finally gets to the bottom of it.

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Loss of Power 13/01/2021 at 11:27 #136333
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kbarber in post 136332 said:
GeoffM in post 136311 said:
Mantis #32795 for investigation later. First glance it looks like LOP survives some transitions but not others.
Which seems entirely prototypical. Sometimes the tapper will kick the right apparatus case in the right way and the train will miraculously recover (it's like the old joke about the plumber's bill). Other times the unit will drag its weary way back to the depot for a shift being gone over, a 'NFF' in the repair book, then promptly fall over as soon as it's let out again. And sometimes that's 'rinse and repeat' for several weeks until the depot finally gets to the bottom of it.
You can't say that for all case though Keith. Maybe in todays railway traction units are easier to fix whilst traffic as most of them have computers with fault diagnostics built in, but back in BR days it was a different kettle of fish altogether. I remember once back in 1986/87 we had 31302 on the depot at Bedford with exactly that fault assigned to it Loss of Power. The TCS asked me to secondman a Toton driver who had worked 6V68 to Bedford back to Toton TMD with this loco. We went out to the loco up & left the holding sdgs. As it was about 04.00am West Hampstead signalled us onto the DF at Bedford North Jn. The driver opened the power handle to maximum & nothing happened. The ammeter only showed about 600-700 amps & that was it. IIRC when the first field divert should have come in around 25-30mph it didn't otherwise the amps would have increased & we would have moved along a bit faster. So the driver stopped the loco opposite the site of Oakley station, got back on the phone to West Hampstead & told them he wasn't taking loco all the way to Toton as it wouldn't have got over Sharnbrook summit. So we returned wrong road from Oakley all the way back to Bedford North Jn before putting the loco back onto the holding sdgs. We'd looked in the engine room & none of the circuit breakers had tripped, there wasn't any sound of regulating air escaping & neither desk had beenleft open despite no key being in the desk as that could cause loss of power if driving from the opposite end of the 'jimmyed' desk. The Loss of power caused the loco not to go over 25-30mph. The loco was dragged away to either Cricklewood TMD or another depot for maintenance.

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Loss of Power 13/01/2021 at 12:30 #136337
peterb
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The current LOP code may well match that of 31302 - a limping loco - but is it prototypical for MUs?

E.g. let's suppose we had a 220, or 185, or an EMU or even a T+T train e.g. HST with one or more engines dead. You would presume that acceleration would be affected, but would it necessarily mean they couldn't hit top speed? Especially on a falling gradient! I'm sure there are examples IRL of a train deliberately running with one or more engines out.

HST discussion

It's maybe something which can be tied in with train characteristics?

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Loss of Power 13/01/2021 at 13:19 #136338
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peterb in post 136337 said:
The current LOP code may well match that of 31302 - a limping loco - but is it prototypical for MUs?

E.g. let's suppose we had a 220, or 185, or an EMU or even a T+T train e.g. HST with one or more engines dead. You would presume that acceleration would be affected, but would it necessarily mean they couldn't hit top speed? Especially on a falling gradient! I'm sure there are examples IRL of a train deliberately running with one or more engines out.

HST discussion

It's maybe something which can be tied in with train characteristics?
A 2car Sprinter would have to terminate at the next nearest place ifit lost one engine as it can't remain in traffic.. Voyagers or Meridians would be OK as all the vehicles in the set are powered even though when running one engine is uaually shut down. Hsts on the other hand if the set had 8 Mk.3 coaches in it would accelerate alot slower for a few reasons. Firstly the HST power cars are Bo-Bo configuration & hauling 8 Mk.3 coaches & a dead power car would probably accelerate no quicker than a Type 2 diesel loco.. EMUs you wouldn't really notice a difference unless traction motos were isolated. Back at the beginning of November last year I took a train from Bedford to London it was a 12 car Cl.700 unit. The train was booked to stop at Luton, Harpenden & St. Albans City only due to Covid. So we left Bedford R/T & travelled on the UF all the way to Luton P4. We ended up standing there for a good 20+ mintes until the driver came onto he PA & told everyone due to a fault with the unit it would be terminating at St. Albans City. We then went forward to Harpenden & then St. Albans City where everyone had to get off. Between Luton & St. Albans there didn't seem to be any difference in performance so what exactly the problem was I just don't know obviously something that mewant the train had to come out of service. We eventually caught the next train from P3 at St. Albans City & actually overtook the train we'd originally been on going into Cricklewood CS. So if this was down to some kind of fault with the trains power control we obviously didn't notice anything. Personally I think it's going to be quite hard for the core code or whatever controls the LOP on trains to get anymore accurate unless as mentioned previously if there was like a percantage tab on the train characteristics tab & the TT writer creating a TT could input the '%' chance of that type of train developing LOP.

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Loss of Power 13/01/2021 at 13:47 #136340
jc92
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peterb in post 136337 said:
I'm sure there are examples IRL of a train deliberately running with one or more engines out.
the aforementioned 185s do this all the time. the onboard computer shuts down engines dependent on how much power is being applied through the power handle, how fast the unit is running and if the unit coasts for a particular length of time. its quite disconcerting at first when the engine drops out at speed and the coach goes quiet but its a fuel efficiency measure. I suspect they would make 100mph on reduced engines, but likely not nearly as quick.

Regarding HST's, I know there's at least two people on here professionally involved with them who can comment better, but I'm sure a single power car would never reach full speed in practice.

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Loss of Power 13/01/2021 at 17:25 #136367
GeoffM
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kbarber in post 136332 said:
GeoffM in post 136311 said:
Mantis #32795 for investigation later. First glance it looks like LOP survives some transitions but not others.
Which seems entirely prototypical. Sometimes the tapper will kick the right apparatus case in the right way and the train will miraculously recover (it's like the old joke about the plumber's bill). Other times the unit will drag its weary way back to the depot for a shift being gone over, a 'NFF' in the repair book, then promptly fall over as soon as it's let out again. And sometimes that's 'rinse and repeat' for several weeks until the depot finally gets to the bottom of it.
There are definitely cases where having 5 minutes at a terminus between arriving and departing is enough to sort an issue; similarly, limping onwards is also possible. I think in terms of SimSig that could be randomised and notified to the user accordingly.

But without more information we don't have, what happens with joins/divides? An 8-car EMU might have a fault that means one unit is dragging the other unit dead (so a loss of power), so after splitting the two units the healthy unit should not have a loss of power.

I'm sure there are arguments for all sorts of ways of handling this.

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Loss of Power 13/01/2021 at 18:25 #136375
GeoffM
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peterb in post 136337 said:
e.g. HST with one or more engines dead. You would presume that acceleration would be affected, but would it necessarily mean they couldn't hit top speed? Especially on a falling gradient!
Not picking on you, more for my interests' sake, but I just had a convo with a driver of HSTs on this forum and he said (reproduced with his permission):
Quote:
As one commenter on that forum said, you could get an HST on one power car up to about 110mph, but it won't go much past that. And that's on a flat piece of line. If you've got hills then they really struggled. That's why we weren't allowed to leave Totnes from a stand on the Down on one engine, as it would struggle quite badly up Rattery bank.
...and

Quote:
I also noticed that someone else in the Rail Forums thread asked about the power car being better on the rear. I would argue that having driven both, it is much better for the working power car to be on the front. One power car pushing an eight-car train is even worse than one pulling it.
Also, (me commenting this time), Railforums does have a lot of... interesting... thoughts sometimes, which may have little bearing on reality.

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Loss of Power 13/01/2021 at 20:40 #136388
peterb
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Geoff,

It's neither my place or inclination to discuss the specifics of what a loss of power means for HSTs in practice (or any other rolling stock for that matter) - I'm trying to illustrate the suggestion that a 'LOP' isn't necessarily as clear cut as a 66% cut in top speed in real life. Rather, that the logic and method of simulating a LOP could be reviewed, determined by the selected speed class.

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