white light on pantograph/catenary

[JinglingGeordie]

Hi,

 

I notice recently when watching trains on the drive to work that there is a constant white light/ flash where the pantograph has contact with the catenary on the 380 ScotRail units.   When I recall the 303 Blue train units or the 318 units I did not see this at all.  I do recall an occassional flash/arcing when electric hauled in a sleeper, and of course the third rail on Sothern region emus could be dazzling.

 

Is this a new thing?   Is it weather related - frost perhaps. 

[Bomag]

On other new units they are fitted with a CCTV camera and lights to monitor the pantograph, I assume the 380s do as well.  the light reflects off the bottom of the pantograph.

[phil-b259]

8 minutes ago, JinglingGeordie said:

Hi,

 

I notice recently when watching trains on the drive to work that there is a constant white light/ flash where the pantograph has contact with the catenary on the 380 ScotRail units.   When I recall the 303 Blue train units or the 318 units I did not see this at all.  I do recall an occassional flash/arcing when electric hauled in a sleeper, and of course the third rail on Sothern region emus could be dazzling.

 

Is this a new thing?   Is it weather related - frost perhaps. 

 

It is a relatively new thing - but nothing to do with frost protection.

 

ALL recent EMU builds (and maybe the class 88 locos) have on board cameras looking at the pantograph for diagnostic purposes and the light is there to enable a good picture.

[JinglingGeordie]

Many thanks to you both.

 

I presume that the practice of lowering the pantograph once at normal maximum speed and gliding is no longer done?

 

[Pete the Elaner]

15 minutes ago, JinglingGeordie said:

I presume that the practice of lowering the pantograph once at normal maximum speed and gliding is no longer done?

 

I have never seen or heard of that practise.

The train would still need power for ETH & other systems.

It would also require raising it again while in motion once speed has reduced slightly. Surely this would risk tearing the wires down?

[phil-b259]

5 hours ago, JinglingGeordie said:

Many thanks to you both.

 

I presume that the practice of lowering the pantograph once at normal maximum speed and gliding is no longer done?

 

 

Erm.... UK trains NEVER lower their pantograph when in service - most onboard services require a constant source of power from the overheads.

 

The only time ‘gliding’ as you put it will happen is either:-

 

(1) The driver spots a potential issue in the overhead wire and manages to lower the pantograph to prevent damage to it or the OLE.

 

(2) Due to engineering work / damage affecting the OLE drivers are instructed to lower their pantographs at a certain point then raise them further on. This needs to be carefully managed as no power = no compressor to recharge the brake cylinders and there is a very real risk of trains becoming stranded.

 

Edited to clarify while railway administrations in other countries may do things differently, the UK only having a single overhead electrification system for trains (note for the pedantic, trams are NOT trains), then lowering and subsequently raising them again in the manor you describe is simply not done here.

Edited November 19, 2019 by phil-b259

[Wickham Green]

There's already a thread on this topic - somewhere - I think it started talking about Thameslink units where the overhead light is still on when the train's operating on the third rail.

[34theletterbetweenB&D]

1 hour ago, JinglingGeordie said:

I notice recently when watching trains on the drive to work that there is a constant white light/ flash where the pantograph has contact with the catenary on the 380 ScotRail units. ...Is this a new thing?   Is it weather related - frost perhaps. 

 

How timely. Have these pantograph illuminators only recently been switched on? A glance this morning at one of the 700 units now operating the KX sub services had me wondering what the white light on the roof was. Yet it would be a rare weekday when I don't see such a unit from above, and have never noticed this previously.

[Joseph_Pestell]

50 minutes ago, phil-b259 said:

 

Erm.... trains NEVER lower their pantograph when in service - most onboard services require a constant source of power from the overheads.

 

The only time ‘gliding’ as you put it will happen is either:-

 

(1) The driver spots a potential issue in the overhead wire and manages to lower the pantograph to prevent damage to it or the OLE.

 

(2) Due to engineering work / damage affecting the OLE drivers are instructed to lower their pantographs at a certain point then raise them further on. This needs to be carefully managed as no power = no compressor to recharge the brake cylinders and there is a very real risk of trains becoming stranded.

 

You can add swing bridges to that list (at least on SNCF).

 

And some SNCF locos/TGVs with different pantographs for 1.5kv and 25kV presumably do the same.

[jim.snowdon]

56 minutes ago, phil-b259 said:

 

Erm.... trains NEVER lower their pantograph when in service - most onboard services require a constant source of power from the overheads.

 

The only time ‘gliding’ as you put it will happen is either:-

 

(1) The driver spots a potential issue in the overhead wire and manages to lower the pantograph to prevent damage to it or the OLE.

 

(2) Due to engineering work / damage affecting the OLE drivers are instructed to lower their pantographs at a certain point then raise them further on. This needs to be carefully managed as no power = no compressor to recharge the brake cylinders and there is a very real risk of trains becoming stranded.

And TGV sets at neutral sections, and as a variation, gaps at bridges on the US East Coast Corridor, where the Pantographs are simply allowed to run off the wire and run back on again at the other side.

 

And any multi-system loco at the boundaries between different electrifications, including 25kV AC to 750V DC at this end of the Channel Tunnel, all done under the direct control of the driver.

 

Jim

[JinglingGeordie]

I recall reading in O S Nocks BGreat locomotives of the 20th Century vol 3 about the Glasgow Blue Trains lowering their pantographs.  It seems odd and as is meintioend above would have an adverse effect of in-train-systems as well as the greater risk of damaging the overhead knitting.

[Wickham Green]

Watching a model layout  - which shall remain nameless - at Tolworth the other day and the pans on a class 76 were going up an' down like yoyos !

[phil-b259]

1 hour ago, jim.snowdon said:

And TGV sets at neutral sections, and as a variation, gaps at bridges on the US East Coast Corridor, where the Pantographs are simply allowed to run off the wire and run back on again at the other side.

 

I assumed the poster was quoting UK practice - so as valid as those observations they are to the countries mentioned, they do not apply to UK operations. Pantographs remain raised in the UK for passage through neutral sections in OLE with lineside magnets used to disconnect and reconnect circuit beakers on the locos instead..

 

1 hour ago, jim.snowdon said:

And any multi-system loco at the boundaries between different electrifications, including 25kV AC to 750V DC at this end of the Channel Tunnel, all done under the direct control of the driver.

 

This is not really the same as 'gliding' as the original poster meant it as the implication is the pantograph is then raised later on once the 'gliding' has ceased.

 

In any case since the transfer of Eurostar to St Pancras the 25KV - 750V changeover at speed doesn't happen any more.

[jim.snowdon]

1 hour ago, phil-b259 said:

 

I assumed the poster was quoting UK practice - so as valid as those observations they are to the countries mentioned, they do not apply to UK operations. Pantographs remain raised in the UK for passage through neutral sections in OLE with lineside magnets used to disconnect and reconnect circuit beakers on the locos instead..

 

 

This is not really the same as 'gliding' as the original poster meant it as the implication is the pantograph is then raised later on once the 'gliding' has ceased.

 

In any case since the transfer of Eurostar to St Pancras the 25KV - 750V changeover at speed doesn't happen any more.

UK practice has a tendency to be rather conservative compared to the rest of the world, and a railway is a railway, wherever it is.

 

Jim

 

 

[phil-b259]

4 hours ago, Joseph_Pestell said:

 

You can add swing bridges to that list (at least on SNCF).

 

And some SNCF locos/TGVs with different pantographs for 1.5kv and 25kV presumably do the same.

 

Naturally the need to cope with different types of overhead electrification will have a big impact - it usually requires separate pantographs and operations at changeover locations may be facilitated by trains coasting (or 'gliding') between different electrical sections with pantographs down.

 

However SNCF do not operate the British railway system and as such any practices they may implement as regards pantograph operation have no reverence to UK operations (other than possibly HS1 and Eurotunnel both of which borrow heavily from SNCF practice).

 

Edited November 19, 2019 by phil-b259

[St. Simon]

6 hours ago, phil-b259 said:

 

Erm.... UK trains NEVER lower their pantograph when in service - most onboard services require a constant source of power from the overheads.

 

The only time ‘gliding’ as you put it will happen is either:-

 

(1) The driver spots a potential issue in the overhead wire and manages to lower the pantograph to prevent damage to it or the OLE.

 

(2) Due to engineering work / damage affecting the OLE drivers are instructed to lower their pantographs at a certain point then raise them further on. This needs to be carefully managed as no power = no compressor to recharge the brake cylinders and there is a very real risk of trains becoming stranded.

 

Edited to clarify while railway administrations in other countries may do things differently, the UK only having a single overhead electrification system for trains (note for the pedantic, trams are NOT trains), then lowering and subsequently raising them again in the manor you describe is simply not done here.

 

Hi Phil.

 

You might want to clarify that it is pure EMU that don't lower and raise their pantograph in service.

 

The Class 80x's do raise and lower their pantographs at linespeed regularly in passenger service.

 

Adding to the answers to the original question on Pantograph lights, the operation of the lights to vary between classes, for instance the Panto lights on the Class 387's aren't on when stationary (or the doors are released, they seem to coincide, but I don't know if they are connected), where as on the Class 80x are on constantly when the Pantograph is raised.

 

Simon 

[Erixtar1992]

6 hours ago, phil-b259 said:

 

Erm.... UK trains NEVER lower their pantograph when in service - most onboard services require a constant source of power from the overheads.

 

 

if that was true the railway would come to a grinding halt when trains go through a neutral section lol

 

you regularly hear the 25kv drop out if you sit in a train under the pantograph, aswell as aircon switching off ect for a few moments

[phil-b259]

26 minutes ago, St. Simon said:

 

Hi Phil.

 

You might want to clarify that it is pure EMU that don't lower and raise their pantograph in service.

 

The Class 80x's do raise and lower their pantographs at linespeed regularly in passenger service.

 

 

 

But again the trigger for this action is a switch to an alternative power source! In that sense its no different to the exercise taken by Eurostar in pre HS-1 days when they switched between 750V third rail and 25KV Overheads.

 

Class 800s do not lower their pantographs for long periods and just coast (or 'glide') along without switching on the diesel engines do they - if they did then I'm sure they would quickly come to a dramatic halt as all on board systems die through a lack of electrical power and the brake cylinders not having any air to keep them off!

 

In short, a class 800 travelling between London and Bristol (via Bristol Parkway) will have its pantograph raised all the way from London to Bristol Parkway - it will not be raised and lowered on a whim to allow coasting / 'gliding' to take place.

 

Similarly I don't believe a 73 can raise its pick up shoes off the third rail and coast along without starting the diesel engine at the same time - and presumably the same is true of the class 88s with regard to their pantographs.

 

PLEASE NOTE:- In all cases we are talking about trains moving at speed -and just to pacify the picky folk on this thread - yes I am fully aware its possible for a stationary loco to simply lower / raise its pantograph or pick up shoes without a secondary power generating device other than basic batteries being present.

 

As has been noted, it seems the French regularly drop then lower their pantographs for neutral sections - but in the UK we have lineside magnets to open / close the necessary circuit beakers on the motive power making this practice unnecessary.

Edited November 19, 2019 by phil-b259

[phil-b259]

23 minutes ago, Erixtar1992 said:

if that was true the railway would come to a grinding halt when trains go through a neutral section lol

 

you regularly hear the 25kv drop out if you sit in a train under the pantograph, aswell as aircon switching off ect for a few moments

 

For F*** sake quit with the pedantry please people!

 

Let me clarify once and for all...

 

I took JinglingGeordie's post to mean:-

 

Driver routinely go round raising and lowering pantographs like a drawers for no other reason than they like 'gliding' along for long distances!

 

This is quite clearly nonsense - yet ever attempt I have made to deal with this has been pulled apart on the basis that "The French do XXX", "Bi- modes do YYYY", and now the revelation that "Neutral sections don't supply power"!

 

NONE OF WHICH IS ACTUALLY EVENT TO WHAT JinglingGeordie, IN POST NO. 4, WAS IMPLYING HAPPENS IN THE UK!

 

 

 

 

Edited November 19, 2019 by phil-b259

[Ken.W]

34 minutes ago, Erixtar1992 said:

if that was true the railway would come to a grinding halt when trains go through a neutral section lol

 

you regularly hear the 25kv drop out if you sit in a train under the pantograph, aswell as aircon switching off ect for a few moments

 

But the pantographs are not, as has previously been said, lowered for neutral sections.

What happens is a track magnet and receiver on the train opens the train's VCB before the neutral section and closes it again after it.

They're basically the same as an AWS permanent magnet and receiver except that they're positioned on the outside of the rail instead of center of the track.

 

In fact, and in relation to the original comment on drivers dropping the pan and 'gliding' as he put it, it's not normally permited to raise a pan at speed.

One exception's specific* power change over points for bi-mode trains.

Another's when "High Speed Coasting" is specially authorized to pass under a damaged section of OHL.         For this to happen the section beyond the affected one needs to be suitable for the pan to be raised (no wire run-offs or crossover lines etc). After the coasting section there's the 'Raise Pan' sign, this is followed by a further board that indicates the limit at which the pan can be raised, and if you pass this without the pan being raised you have to stop, or at least reduce to 20mph, to do so.

* With the 800 training runs, we were at the time having to change over power mode at Darlington due to the restriction at the time on them using  the OHL north of there. This isn't a normal power change over location so we were required to stop to do so.

[jim.snowdon]

10 minutes ago, Ken.W said:

Another's when "High Speed Coasting" is specially authorized to pass under a damaged section of OHL.         For this to happen the section beyond the affected one needs to be suitable for the pan to be raised (no wire run-offs or crossover lines etc). After the coasting section there's the 'Raise Pan' sign, this is followed by a further board that indicates the limit at which the pan can be raised, and if you pass this without the pan being raised you have to stop, or at least reduce to 20mph, to do so.

* With the 800 training runs, we were at the time having to change over power mode at Darlington due to the restriction at the time on them using  the OHL north of there. This isn't a normal power change over location so we were required to stop to do so.

That's why I viewed UK practice as being conservative. The French, for example, were doing the DC to AC changeover onto the LGV at line speed long before anyone in the UK thought it was possible, and under manual control as well.

 

Jim

[MidlandRed]

The 700s have always had the white pantograph light operating whilst on 3rd rail - it's noticeable in daylight when seen from platform level but even more so in the dark as it's actually a bright light source, looking particularly odd if the unit's travelling away from you into the dark and the tail lights are hidden behind a bridge pier, for instance. 

 

I noticed a Pendolino class 390 with a pantograph light at Euston a few evenings ago - have they all got these or are they retro-fit?

 

Im not sure exactly where the changeover occurs but according to the lineside signs, the class 395 Javelins change from 750 v DC 3rd rail to 25 kv overhead and cab signalling and vice versa just east of the platforms at Ebbsfleet International on the North Kent line link - so although not high speed this appears to happen on the move. 

[Pete the Elaner]

7 hours ago, MidlandRed said:

I noticed a Pendolino class 390 with a pantograph light at Euston a few evenings ago - have they all got these or are they retro-fit?

 

There were just 2 of them (104 & 010). I don't think they would have been there from new & I have not noticed them on any others, so I think it is still just the 2.

[The Border Reiver]

The new class 397 have very bright pantograph lights

[The Stationmaster]

12 hours ago, jim.snowdon said:

That's why I viewed UK practice as being conservative. The French, for example, were doing the DC to AC changeover onto the LGV at line speed long before anyone in the UK thought it was possible, and under manual control as well.

 

Jim

And doing it on classic lines at line speed for many years before that.  Of course they are not the only railway in Europe operating multi-current/multi-pantograph locos which means they are not the only railway in Europe where pans are raised and lowered at line speed although it can sometimes be spectacular to watch from the lineside.  SNCF similarly have circuit breaker closing and opening at neutral sections under the direct control of the Driver including at maximum running speeds on LGVs and judging by what I have seen when riding in the cab on two LGV routes that appears to be no problem at all for the Driver (and of course it happens in the UK on CTRL aka HS1).

 

Having seen how SNCF and SNCB do things I would agree entirely that UK attitude to some aspects of electric train operation is very conservative.  It always used to be very amusing to watch dual voltage EMUs on the West London Line stopping just south of Mitre Bridge to changeover to 3rd rail from 25kv overhead - very strange when you knew that Class 373 Eurostars were doing the same changeover elsewhere at 100mph.