In message <j88mraF19m7U1@mid.individual.net>, at 08:06:02 on Wed, 2 Mar
2022, Marland <gemehabal@btinternet.co.uk> remarked:

>Conversation with a Southampton student yesterday seems to support
>that as amongst themselves they were calling it a Voi scooter, Voi
>being the licensed operator for the Southampton trial.

Same as Cambridge then.
--
Roland Perry

In message <j88qd5F1up0U1@mid.individual.net>, at 09:06:45 on Wed, 2 Mar
2022, Marland <gemehabal@btinternet.co.uk> remarked:
>Marland <gemehabal@btinternet.co.uk> wrote:
>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>> On 01/03/2022 20:42, NY wrote:
>>
>>>> trains in an electrical section, would that have prevented the scooter
>>>> catching fire? The report doesn't clarify whether it was a
>>>> petrol-powered scooter (effectively a step-through motorbike) or whether
>>>> it was an electric scooter?
>>>
>>> Almost certainly an electric scooter, Southampton is one of the
>>> so-called test locations to try them out. Makes being a pedestrian there
>>> even more hazardous than usual.
>>
>> Conversation with a Southampton student yesterday seems to support that
>> as amongst themselves
>> they were calling it a Voi scooter, Voi being the licensed operator for
>> the Southampton trial.
>>
>> Some suggestion was made that those who did it had not fully grasped the
>> rapid charging procedure.
>>
>Not so sure the student Buzz was that accurate, the Voi scooters are red
>and reasonably substantial,

In Cambridge pink, but they also have pink electric bikes.

>this shot probably taken from the over bridge shoes the remains of a
>yellow/green machine much lighter in construction may not have even be
>electric unless those components have been fully burnt away , but at least
>nothing like a Vesta or Lambretta style machine.
>
><https://twitter.com/ani/status/1498395056214089731>

I agree that isn't a Voi scooter of the kind in Cambridge.

<https://www.camcycle.org.uk/images/blog/article31-pic1-692x1024.jpg>

--
Roland Perry

<Muttley@dastardlyhq.com> wrote:
> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>> They might want to think about updating the circuit breaker.
>>>
>>>
>>
>> Then it'd probably trip when multiple trains took power at the same time.
>
> This would have been a dead short from a metal scooter.

Probably not a clean contact though especially after the metal starts to
burn away,it won’t be much different than an apprentice taking their first
steps with an arc welder. Lots of sparks ,smoke and flashing but an
imperfect joint that just gets worse till the metal has melted.
So not a dead short like a correctly placed short circuiting bar would
cause but imperfect contact
with varying but usually high resistance.

Plus its probably not
> beyond the wit of man for the signalling and power supply to be integrated
> so it knows when there's a train there/not there and can trip accordingly.
>
More stuff to go wrong for what is really a rare event, and how do you
differentiate between a fault caused by debris on the line or a fault on a
train ,or even a train that collides with an object like a scooter or tin
drum that was very close to the live rail but doesn’t make contact till the
passing train disturbs it so the object does.

GH

On 2 Mar 2022 09:49:44 GMT
Marland <gemehabal@btinternet.co.uk> wrote:
><Muttley@dastardlyhq.com> wrote:
>> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>
>>>> They might want to think about updating the circuit breaker.
>>>>
>>>>
>>>
>>> Then it'd probably trip when multiple trains took power at the same time.
>>
>> This would have been a dead short from a metal scooter.
>
>Probably not a clean contact though especially after the metal starts to
>burn away,it won’t be much different than an apprentice taking their first
>steps with an arc welder. Lots of sparks ,smoke and flashing but an
>imperfect joint that just gets worse till the metal has melted.
>So not a dead short like a correctly placed short circuiting bar would
>cause but imperfect contact
>with varying but usually high resistance.
>
>
>Plus its probably not
>> beyond the wit of man for the signalling and power supply to be integrated
>> so it knows when there's a train there/not there and can trip accordingly.
>>
>More stuff to go wrong for what is really a rare event, and how do you
>differentiate between a fault caused by debris on the line or a fault on a
>train ,or even a train that collides with an object like a scooter or tin
>drum that was very close to the live rail but doesn’t make contact till the
>passing train disturbs it so the object does.

Huh?

Trains take X amount, anything greater then trip. If no trains in area then
trip at lower Y amount.

On 02/03/2022 06:52, Graeme Wall wrote:
> On 01/03/2022 17:14, Marland wrote:
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>
>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>> Remind me again why 3rd rail electrification is such a good idea? ;)
>>
>> To be honest a bicycle thrown off an overbridge onto  catenary can be
>> a bit disruptive as well.
>>
>> I’m just surprised it doesn’t happen more often.

There's some danger to the vandal. No one's quite sure how close to the
power you can safely stand whilst holding a large piece of metal. There
are safer ways to annoy people.

> Especially in Southampton, I'm mildly surprised that the scooter hire
> companies are still there given their machines are routinely vandalised
> and dumped all over the city.

I hear some electrified lines have to deal with 50 cycles per second.

<Muttley@dastardlyhq.com> wrote:
> On Tue, 1 Mar 2022 16:50:14 -0000 (UTC)
> Recliner <recliner.usenet@gmail.com> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>> They might want to think about updating the circuit breaker.
>>>
>>
>> So that it blows every time a 10-car train leaves the station?
>
> I doubt a 10 car train is the same way as a metal scooter causing a dead
> short which is almost certainly what this was with the fuel then catching
> fire.
>
>

The problem is that the maximum legitimate current draw by trains is very
close to the dead short current; and if te object causing the short has
some resistance rather than being a solid chunk of metal, or is
sufficiently far from the feed that the rails in between add sufficient
resistance to the circuit, a short might not be sufficient to trip the
breakers.

Anna Noyd-Dryver

<Muttley@dastardlyhq.com> wrote:
> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>> They might want to think about updating the circuit breaker.
>>>
>>>
>>
>> Then it'd probably trip when multiple trains took power at the same time.
>
> This would have been a dead short from a metal scooter.

But evidently not drawing enough current to trip the breakers, which will
be set at a level to allow for the maximum legitimate draw from trains.

> Plus its probably not
> beyond the wit of man for the signalling and power supply to be integrated
> so it knows when there's a train there/not there and can trip accordingly.
>
>

You've just trebled the cost of installation and the likelihood of
failures.

Anna Noyd-Dryver

<Muttley@dastardlyhq.com> wrote:
> On Tue, 1 Mar 2022 22:00:08 -0000 (UTC)
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> ColinR <rail@greystane.shetland.co.uk> wrote:
>>> On 01/03/2022 20:04, Anna Noyd-Dryver wrote:
>>>> <Muttley@dastardlyhq.com> wrote:
>>>>> On Tue, 1 Mar 2022 15:53:21 -0000 (UTC)
>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>>>
>>>>>>>
>>>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>>>>
>>>>>>
>>>>>> Remind me again why 3rd rail electrification is such a good idea? ;)
>>>>>
>>>>> https://www.youtube.com/watch?v=6AGHeJSygp8
>>>>>
>>>>>
>>>>
>>>> The pan-drop ones would be solved by opening the VCB/ABB (main circuit
>>>> breaker on the loco/unit) before dropping the pan, as I thought every
>>>> traction would do automatically.
>>>>
>>>> The one going across the section break would not occur if the equipment in
>>>> the OLE was properly adjusted, I think.
>>>>
>>>> Also, all extinguished themselves safely.
>>>>
>>>
>>> OLE flashes, interesting video but as you say all extinguished
>>> themselves. 3rd rail, many flashes in normal operation, again
>>> extinguishing themselves. No real difference.
>>>
>>> As to a scooter being dropped onto a live conductor, although the proof
>>> is with the 3rd rail incident, I suspect something similar would happen
>>> with an appropriate lump of metal being dropped onto OLE. And, it could
>>> well be that knitting would need significant repair. I suspect the more
>>> robust 3rd rail in this incident required a lot less rectification work.
>>>
>>
>> Because the voltage is higher, the trip current for OLE is a lot lower, so
>> you wouldn't get sustained arcing like this.
>
> Any sane system uses voltage drop as the trip, not current draw. If the
> voltage difference between the OLE and ground goes to 0 its been shorted.
>
>

That's not how electricity works. The voltage at the feed location (where
the breakers etc will be located) won't drop to zero because it's still
being fed!

As an example, all the petrol cars I currently possess have the battery at
the opposite end of the vehicle to the engine. Put a short across the
starter motor leads in the engine bay and the voltage measured across the
battery terminals won't suddenly drop to zero!

Anna Noyd-Dryver

Marland <gemehabal@btinternet.co.uk> wrote:

> Not so sure the student Buzz was that accurate, the Voi scooters are red
> and reasonably substantial,
> this shot probably taken from the over bridge shoes the remains of a
> yellow/green machine much lighter in construction may not have even be
> electric unless those components have been fully burnt away , but at least
> nothing like a Vesta or Lambretta style machine.
>
> <https://twitter.com/ani/status/1498395056214089731>
>

This is the link you meant, I think
<https://mobile.twitter.com/nftdrippy/status/1498743877863456776>.

That definitely looks like a simple unpowered scooter.

Anna Noyd-Dryver

On 02/03/2022 11:14, Anna Noyd-Dryver wrote:
> <Muttley@dastardlyhq.com> wrote:
>> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>
>>>> They might want to think about updating the circuit breaker.
>>>
>>> Then it'd probably trip when multiple trains took power at the same time.
>>
>> This would have been a dead short from a metal scooter.
>
> But evidently not drawing enough current to trip the breakers, which will
> be set at a level to allow for the maximum legitimate draw from trains.
>
>> Plus its probably not
>> beyond the wit of man for the signalling and power supply to be integrated
>> so it knows when there's a train there/not there and can trip accordingly.
>
> You've just trebled the cost of installation and the likelihood of
> failures.

I had a similar idea but decided that it wouldn't be feasible. I think
there are even a few (possibly overseas tram) lines which are powered
only when in use by an actual vehicle, but either option sounds very
impractical on a larger scale.

In message <svnjhr$1u8$4@dont-email.me>, at 11:14:04 on Wed, 2 Mar 2022,
Anna Noyd-Dryver <anna@noyd-dryver.com> remarked:
>Marland <gemehabal@btinternet.co.uk> wrote:
>
>> Not so sure the student Buzz was that accurate, the Voi scooters are red
>> and reasonably substantial,
>> this shot probably taken from the over bridge shoes the remains of a
>> yellow/green machine much lighter in construction may not have even be
>> electric unless those components have been fully burnt away , but at least
>> nothing like a Vesta or Lambretta style machine.
>>
>> <https://twitter.com/ani/status/1498395056214089731>
>
>This is the link you meant, I think
><https://mobile.twitter.com/nftdrippy/status/1498743877863456776>.
>
>That definitely looks like a simple unpowered scooter.

A child's toy, even.
--
Roland Perry

Certes <none@nowhere.net> wrote:
> On 02/03/2022 11:14, Anna Noyd-Dryver wrote:
>> <Muttley@dastardlyhq.com> wrote:
>>> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>> <Muttley@dastardlyhq.com> wrote:
>>>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>>
>>>>> They might want to think about updating the circuit breaker.
>>>>
>>>> Then it'd probably trip when multiple trains took power at the same time.
>>>
>>> This would have been a dead short from a metal scooter.
>>
>> But evidently not drawing enough current to trip the breakers, which will
>> be set at a level to allow for the maximum legitimate draw from trains.
>>
>>> Plus its probably not
>>> beyond the wit of man for the signalling and power supply to be integrated
>>> so it knows when there's a train there/not there and can trip accordingly.
>>
>> You've just trebled the cost of installation and the likelihood of
>> failures.
>
> I had a similar idea but decided that it wouldn't be feasible. I think
> there are even a few (possibly overseas tram) lines which are powered
> only when in use by an actual vehicle, but either option sounds very
> impractical on a larger scale.
>

The system with a power rail embedded in the road surface is only energised
when it's underneath the vehicle.

<https://en.m.wikipedia.org/wiki/Ground-level_power_supply>

Anna Noyd-Dryver

<Muttley@dastardlyhq.com> wrote:
> On 2 Mar 2022 09:49:44 GMT
> Marland <gemehabal@btinternet.co.uk> wrote:
>> <Muttley@dastardlyhq.com> wrote:

>>>>
>>>> Then it'd probably trip when multiple trains took power at the same time.
>>>
>>> This would have been a dead short from a metal scooter.
>>
>> Probably not a clean contact though especially after the metal starts to
>> burn away,it won’t be much different than an apprentice taking their first
>> steps with an arc welder. Lots of sparks ,smoke and flashing but an
>> imperfect joint that just gets worse till the metal has melted.
>> So not a dead short like a correctly placed short circuiting bar would
>> cause but imperfect contact
>> with varying but usually high resistance.
>>
>>
>> Plus its probably not
>>> beyond the wit of man for the signalling and power supply to be integrated
>>> so it knows when there's a train there/not there and can trip accordingly.
>>>
>> More stuff to go wrong for what is really a rare event, and how do you
>> differentiate between a fault caused by debris on the line or a fault on a
>> train ,or even a train that collides with an object like a scooter or tin
>> drum that was very close to the live rail but doesn’t make contact till the
>> passing train disturbs it so the object does.
>
> Huh?
>
> Trains take X amount, anything greater then trip. If no trains in area then
> trip at lower Y amount.
>
>

So how do you differentiate between a large laden 12 coach train under
full acceleration and a light
laden 4 car unit that is just rolling by drawing little more power than the
lights and the brake compressors? The X amount will vary considerably so is
your proposal to have settings at U V W
amounts as well?

You would end up with a monitoring systems so complex that failures would
cause so many interruptions the cure would be worse than the disease.
You can see similar thinking in modern cars where a sensor costing a couple
of quid
has crippled the vehicle but getting the correct solution costs £100’s
while different laptop operators search often in vain for a fault and the
customer decides it is more cost effective to scrap it.

Your suggestion is typical impractical Boltar Bollocks which you come up
with sometimes when you have shot from the hip without thinking of the
practicalities, any further posts to support are just face saving exercises
that confirm your place as part of the software and IT generation who have
fucked up so many things by over complicating them just because you could .

GH

Certes <none@nowhere.net> wrote:
> On 02/03/2022 06:52, Graeme Wall wrote:
>> On 01/03/2022 17:14, Marland wrote:
>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>
>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>
>>>> Remind me again why 3rd rail electrification is such a good idea? ;)
>>>
>>> To be honest a bicycle thrown off an overbridge onto  catenary can be
>>> a bit disruptive as well.
>>>
>>> I’m just surprised it doesn’t happen more often.
>
> There's some danger to the vandal. No one's quite sure how close to the
> power you can safely stand whilst holding a large piece of metal. There
> are safer ways to annoy people.
>
>> Especially in Southampton, I'm mildly surprised that the scooter hire
>> companies are still there given their machines are routinely vandalised
>> and dumped all over the city.
>
> I hear some electrified lines have to deal with 50 cycles per second.

[applause]

Sam

--
The entity formerly known as Sam.Wilson@ed.ac.uk
Spit the dummy to reply

On Wed, 2 Mar 2022 11:14:03 -0000 (UTC)
Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
><Muttley@dastardlyhq.com> wrote:
>> Any sane system uses voltage drop as the trip, not current draw. If the
>> voltage difference between the OLE and ground goes to 0 its been shorted.
>>
>>
>
>That's not how electricity works. The voltage at the feed location (where
>the breakers etc will be located) won't drop to zero because it's still
>being fed!
>
>As an example, all the petrol cars I currently possess have the battery at
>the opposite end of the vehicle to the engine. Put a short across the
>starter motor leads in the engine bay and the voltage measured across the
>battery terminals won't suddenly drop to zero!

No, but the voltage between the battery terminal and the ground side of the
starter motor will be which is what matters. If leccy didn't work like this
most digital electronics , and possibly analogue , wouldn't work as pulling
up or pulling down to 0 is everywhere.

On Wed, 2 Mar 2022 11:14:03 -0000 (UTC)
Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
><Muttley@dastardlyhq.com> wrote:
>> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>
>>>> They might want to think about updating the circuit breaker.
>>>>
>>>>
>>>
>>> Then it'd probably trip when multiple trains took power at the same time.
>>
>> This would have been a dead short from a metal scooter.
>
>But evidently not drawing enough current to trip the breakers, which will
>be set at a level to allow for the maximum legitimate draw from trains.

Or the breakers weren't set up properly.

>> Plus its probably not
>> beyond the wit of man for the signalling and power supply to be integrated
>> so it knows when there's a train there/not there and can trip accordingly.
>>
>>
>
>You've just trebled the cost of installation and the likelihood of
>failures.

Cost possibly, failure not really because if the signalling is wonky then
no ones going anywhere anyway plus there could always be a manual override
from the control centre.

On 2 Mar 2022 12:00:33 GMT
Marland <gemehabal@btinternet.co.uk> wrote:
><Muttley@dastardlyhq.com> wrote:
>> Trains take X amount, anything greater then trip. If no trains in area then
>> trip at lower Y amount.
>>
>>
>
>So how do you differentiate between a large laden 12 coach train under
>full acceleration and a light
>laden 4 car unit that is just rolling by drawing little more power than the
>lights and the brake compressors? The X amount will vary considerably so is
>your proposal to have settings at U V W
>amounts as well?
>
>You would end up with a monitoring systems so complex that failures would
>cause so many interruptions the cure would be worse than the disease.
>You can see similar thinking in modern cars where a sensor costing a couple
>of quid
>has crippled the vehicle but getting the correct solution costs £100’s
>while different laptop operators search often in vain for a fault and the
>customer decides it is more cost effective to scrap it.

Trains already are unnecessarily complicated, eg GPS door opening, having to
"reboot" after a power trip.

>Your suggestion is typical impractical Boltar Bollocks which you come up
>with sometimes when you have shot from the hip without thinking of the

In cab signalling is coming and the train already knows how many units it
has so that info could be fed back on the downlink and hence to the breaker
amongst other things. Or it could be done from the control centre. Whats the
problem?

>practicalities, any further posts to support are just face saving exercises
>that confirm your place as part of the software and IT generation who have
>fucked up so many things by over complicating them just because you could .

Presumably you'd still be happy with steam trains, semaphore signals and a
bloke in a cabin who spends most of the day reading the paper with a few
minutes every hour when he has to get up and pull a lever?

Frankly a breaker that can't tell the difference between a fully loaded train
and a short seems pointless. Might just as well let the cables burn out.

On 2022-03-02 09:23:22 +0000, Muttley@dastardlyhq.com said:

> On Tue, 1 Mar 2022 22:00:08 -0000 (UTC)
> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>> ColinR <rail@greystane.shetland.co.uk> wrote:
>>> On 01/03/2022 20:04, Anna Noyd-Dryver wrote:
>>>> <Muttley@dastardlyhq.com> wrote:
>>>>> On Tue, 1 Mar 2022 15:53:21 -0000 (UTC)
>>>>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>>>
>>>>>>>
>>>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>>>>
>>>>>>
>>>>>> Remind me again why 3rd rail electrification is such a good idea? ;)
>>>>>
>>>>> https://www.youtube.com/watch?v=6AGHeJSygp8
>>>>>
>>>>>
>>>>
>>>> The pan-drop ones would be solved by opening the VCB/ABB (main circuit
>>>> breaker on the loco/unit) before dropping the pan, as I thought every
>>>> traction would do automatically.
>>>>
>>>> The one going across the section break would not occur if the equipment in
>>>> the OLE was properly adjusted, I think.
>>>>
>>>> Also, all extinguished themselves safely.
>>>>
>>>
>>> OLE flashes, interesting video but as you say all extinguished
>>> themselves. 3rd rail, many flashes in normal operation, again
>>> extinguishing themselves. No real difference.
>>>
>>> As to a scooter being dropped onto a live conductor, although the proof
>>> is with the 3rd rail incident, I suspect something similar would happen
>>> with an appropriate lump of metal being dropped onto OLE. And, it could
>>> well be that knitting would need significant repair. I suspect the more
>>> robust 3rd rail in this incident required a lot less rectification work.
>>>
>>
>> Because the voltage is higher, the trip current for OLE is a lot lower, so
>> you wouldn't get sustained arcing like this.
>
> Any sane system uses voltage drop as the trip, not current draw. If the
> voltage difference between the OLE and ground goes to 0 its been shorted.

Taking an example, a 3x class 450 set, something not uncommon on the
network, has an installed power of 6 MW, so at full load on 750 V DC
will draw 8 kA. If a substation has to be able to allow, say, three
such trains to be in section together (say, somewhere like London
Bridge, or Clapham Junction), you have a situation where a *normal*
demand might be 24 kA @ 750 V. If you drop something like a
scaffolding pole onto a 3rd rail line so that it shorts the conductor
rail to the running rail, the electrical contact at the points where it
touches the rails will not be good enough to allow it to draw that kind
of current, so any electrical measurements at the substation will be
unable to distinguish between that kind of a fault and a normal rush
hour, regardless of what kind of measurements you make, because a
normal rush hour and a severe fault, from the substation, look the same.

Robin

On 2022-03-01 21:04:56 +0000, Chris J Dixon said:

> NY wrote:
>
>> Do trains still carry a device for deliberately tripping the third-rail
>> circuit breakers in the event of a crash so the power is removed *and stays
>> removed* to make it safe to rescue people? What sort of current flows while
>> that is applied, and how much headroom is there over and above the normal
>> current drawn by all the trains in an electrical section in the worst case
>> where they are all setting off from rest?
>
> Yes AFAIK, they do still carry a shorting bar, a device which is
> not to be used lightly.
>
> I have not seen one used, but I gather the instruction is to turn
> your back on it as it is applied, to avoid seeing the arc.
>
> The fault current is of the order of thousands of Amps, and it is
> said that there are indeed parts of the network where the
> distance from the section breaker is such that it is not
> guaranteed to trip.

More like 10s of thousands of amps. A 12 car unit at normal rated
power will draw something like 6 kA, and a substation will have to be
able to support more than a single train in section, so >10 kA would
not be recognisable as a fault condition.

Robin

On Wed, 2 Mar 2022 09:20:19 -0000 (UTC), Muttley@dastardlyhq.com
wrote:

>On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>><Muttley@dastardlyhq.com> wrote:
>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>> They might want to think about updating the circuit breaker.
>>>
>>>
>>
>>Then it'd probably trip when multiple trains took power at the same time.
>
>This would have been a dead short from a metal scooter. Plus its probably not
>beyond the wit of man for the signalling and power supply to be integrated
>so it knows when there's a train there/not there and can trip accordingly.
>
How much current would a diesel locomotive draw?

On 02/03/2022 20:15, Charles Ellson wrote:
> On Wed, 2 Mar 2022 09:20:19 -0000 (UTC), Muttley@dastardlyhq.com
> wrote:
>
>> On Tue, 1 Mar 2022 20:04:21 -0000 (UTC)
>> Anna Noyd-Dryver <anna@noyd-dryver.com> wrote:
>>> <Muttley@dastardlyhq.com> wrote:
>>>> On Tue, 1 Mar 2022 15:41:49 +0000
>>>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>>
>>>> They might want to think about updating the circuit breaker.
>>>>
>>>>
>>>
>>> Then it'd probably trip when multiple trains took power at the same time.
>>
>> This would have been a dead short from a metal scooter. Plus its probably not
>> beyond the wit of man for the signalling and power supply to be integrated
>> so it knows when there's a train there/not there and can trip accordingly.
>>
> How much current would a diesel locomotive draw?

Roughly the same as a stopped or coasting EMU.

> so any electrical measurements at the substation will be unable to
> distinguish between that kind of a fault and a normal rush hour,
> regardless of what kind of measurements you make, because a normal rush
> hour and a severe fault, from the substation, look the same.

And that is the main issue with the 3rd rail system. Because the rail is
near the ground the voltage has to be low, that means with modern high
performance trains that have significant auxiliary loads (like high
volume air conditioning) as well has high performance traction, it
becomes difficult to tell the difference between a normal peak load and
a fault.

This is a problem with lower voltage overhead electrification too. I'm
aware of a fault on a 600v tram network were the fault on the tram did
not trip the substation (which was set to supply dozens of cars in
section), the tram caught on fire and the power stayed on feeding energy
into the burning fault till the over head sagged due to it getting got
and eventually fell, breaking the circuit.
The power was turned off by control when the emergency services turned
up and requested safe isolation, not the circuit tripping on the fault.
The operators here had the choice of lots of nuisance tripping in the
peak hour or poor detection of faults.

On Tue, 01 Mar 2022 15:53:21 +0000, Anna Noyd-Dryver wrote:

> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>
>
>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>
>>
> Remind me again why 3rd rail electrification is such a good idea? ;)
>
>
> Anna Noyd-Dryver

Looking for something else, I caught this on Wikipedia under Railway
Electrification in Great Britain:

"In June 2011 Peter Dearman of Network Rail suggested that the third-rail
network will need to be converted into overhead lines. He stated:
'Although the top speed is 100 mph, the trains cannot go over 80 mph well
and 25% of power is lost from heat.' Agreeing that conversion would be
expensive, he said that the third rail network is at the limit of its
power capability, especially as trains become more advanced in technology.
"The July 2012 Department for Transport High Level Output
Specification for Network Rail Control Period 5 includes the conversion
of the South West Main Line between Southampton Central and Basingstoke
from 750 V DC third rail to 25 kV AC overhead as part of a scheme to
improve rail freight capacity from Southampton Port. This conversion
would be a pilot scheme to develop a business case for full conversion
of the third-rail network. The Office of Rail and Road (ORR) has
also stated that, on safety grounds, third-rail 750 V DC has a limited
future."

nib

nib <news@ingram-bromley.co.uk> wrote:
> On Tue, 01 Mar 2022 15:53:21 +0000, Anna Noyd-Dryver wrote:
>
>> Graeme Wall <rail@greywall.demon.co.uk> wrote:
>>
>>
>>> <https://www.bbc.co.uk/news/av/uk-england-hampshire-60571022>
>>>
>>>
>> Remind me again why 3rd rail electrification is such a good idea? ;)
>>
>>
>> Anna Noyd-Dryver
>
> Looking for something else, I caught this on Wikipedia under Railway
> Electrification in Great Britain:
>
> "In June 2011 Peter Dearman of Network Rail suggested that the third-rail
> network will need to be converted into overhead lines. He stated:
> 'Although the top speed is 100 mph, the trains cannot go over 80 mph well
> and 25% of power is lost from heat.' Agreeing that conversion would be
> expensive, he said that the third rail network is at the limit of its
> power capability, especially as trains become more advanced in technology.

Peter Dearman had a rather rose-tinted vision about the ease of installing
OHLE. Here's what he had to say about the pending GWR OHLE project. If
only he'd known what he was talking about when he said:

There’s been mention in the press of a high output factory train. What’s
the current position with this?

“The term is a bit misleading. It’s more of a factory system and will
include a piling train, a steel erection train and also the vehicles
required to enable the OLE to be attached to the masts and the wires to be
run.

“In a way it’s a compilation of all the bits of kit that used to run around
separately but it’ll be a much slicker version of that – in fact our wiring
vehicle (and there are versions of this in Europe so this isn’t way-out
technology) will be able to run both the catenary and contact wires at
tension in one run.

“That has massive implications for productivity. I anticipate that as we
move forward into full production and once the guys on the train become
familiar with all the kit, we should be getting two wire runs a night…at
tension.

<https://railuk.com/people/an-interview-with-network-rails-head-of-network-electrification/>

>
> "The July 2012 Department for Transport High Level Output
> Specification for Network Rail Control Period 5 includes the conversion
> of the South West Main Line between Southampton Central and Basingstoke
> from 750 V DC third rail to 25 kV AC overhead as part of a scheme to
> improve rail freight capacity from Southampton Port. This conversion
> would be a pilot scheme to develop a business case for full conversion
> of the third-rail network. The Office of Rail and Road (ORR) has
> also stated that, on safety grounds, third-rail 750 V DC has a limited
> future."

As we know, that scheme was abandoned.

Bob wrote:

>On 2022-03-01 21:04:56 +0000, Chris J Dixon said:

>> Yes AFAIK, they do still carry a shorting bar, a device which is
>> not to be used lightly.
>>
>> I have not seen one used, but I gather the instruction is to turn
>> your back on it as it is applied, to avoid seeing the arc.
>>
>> The fault current is of the order of thousands of Amps, and it is
>> said that there are indeed parts of the network where the
>> distance from the section breaker is such that it is not
>> guaranteed to trip.
>
>More like 10s of thousands of amps. A 12 car unit at normal rated
>power will draw something like 6 kA, and a substation will have to be
>able to support more than a single train in section, so >10 kA would
>not be recognisable as a fault condition.

Indeed, I was being a little conservative there.

One of the most impressive bangs I saw was at Switchgear Testing
Company in Trafford Park. Most of the adjacent GEC site, where I
had once worked, had gone, and this remnant was a sad shadow of
its former self, with weeds growing through the concrete. Looking
at the mapping sites, it now looks as if all traces have been
removed.

The device under test was a railway shoe fuse, intended for the
dc Electrostars. It consists of a bare copper strip in an
open-sided fibreglass enclosure, which contains hidden metalwork
to produce a magnetic blowout effect.

We did a trial shot at 10 kA for 1 second, which merely caused a
slight colour change. At 30 kA, I was very glad to be behind the
ballistic glass. As the copper strip blew apart the shower of
sparks was terrific.

We needed to do the test because for Electrostar we had to change
the incoming cable orientation, to suit the underframe layout,
and there was concern that this might have an effect upon the
blowout action. As it happened, all was well.

Chris
--
Chris J Dixon Nottingham UK
chris@cdixon.me.uk @ChrisJDixon1

Plant amazing Acers.