Pendolino Pantographs

[Crossover]

Much, much shorter!

The actual neutral bit is a matter of centimetres isn't it? Just the VCB's open the circuits quite a way before and close quite a way after. I'm sure I have heard that a Pendo couldn't ever get stranded in a neutral section as one pantograph should always be capable of being in touch with a live wire (as long as both are working)

 

[edwin_m]

i.e the high voltage bus doesn't run through the coupler head (which would make sense as those pins wouldn't take such power!)?

I think there would be some safety concerns too!

I don't think any railway tries to feed traction power, whether DC or AC, through any sort of auto-coupler.

 

[Philip Phlopp]

The actual neutral bit is a matter of centimetres isn't it? Just the VCB's open the circuits quite a way before and close quite a way after. I'm sure I have heard that a Pendo couldn't ever get stranded in a neutral section as one pantograph should always be capable of being in touch with a live wire (as long as both are working)

Centimetres is just about appropriate, yes. They're typically 10 metres or so (differences vary slightly depending on type).

And yes, a Pendolino can't get stranded as a result.

 

[LeylandLen]

Pardon my ignorance , but does this thread refer to Pendelinos in general , whether 9 or 11 cars? I do use the WCML between Preston/Manchester and Euston and never really thought about seeing which pantograph is in use
Surely an 11 carriage 390 being heavier needs more power?
Also the forces applied to the pantographs in tilt mode through the Lake District must be enormous ? How long do the pantographs last in miles?

 

[swt_passenger]

Surely an 11 carriage 390 being heavier needs more power?
Also the forces applied to the pantographs in tilt mode through the Lake District must be enormous ? How long do the pantographs last in miles?

The longer Pendolino does draw more power, and has more onboard traction equipment, (3 transformers? ) but it still only needs one pantograph up as they are all linked by the train's 25 kV bus line.

The whole pantograph mechanism is moved sideways across the roof by a belt drive in an opposite and equal amount to the train tilt, so the effect of tilt of the train is cancelled out.

EDIT Found the post from a few months back with a photo of the mechanism: http://www.railforums.co.uk/showpost.php?p=2547978&postcount=6

 

[Mordac]

Centimetres is just about appropriate, yes. They're typically 10 metres or so (differences vary slightly depending on type).

And yes, a Pendolino can't get stranded as a result.

That's good to know, I always worry at Carstairs Junction with its two very close neutral sections that we're going to get stranded just as someone escapes the State Hospital and attempts to hitch hike!

 

[Philip Phlopp]

That's good to know, I always worry at Carstairs Junction with its two very close neutral sections that we're going to get stranded just as someone escapes the State Hospital and attempts to hitch hike!

You'll hear the air-raid sirens first, and I think, if there's an escapee, the instruction goes out for trains not to stop at Carstairs Junction.

 

[Mordac]

You'll hear the air-raid sirens first, and I think, if there's an escapee, the instruction goes out for trains not to stop at Carstairs Junction.

That assumes the escape has been detected!

And trains would still need to slow to a crawl to get into the Edinburgh branch, which is the one I use. At least if I'm on a Voyager I don't worry about losing power. It's the juxtaposition of two neutral sections so close to each other on such a low speed area that makes it so nail-biting. Do you know a train has ever got stuck there? I would find it very likely, although I suppose the Pendos are so long one of the pantographs is always under energized wire.

 

[SpacePhoenix]

If a Pendolino ever does end up in the unfortunate position of having its raised pantograph in a neutral section when stopped (does it ever happen?), can the driver just lower that pantograph, raise the other, then move the train clear then swap pantographs back?

 

[Philip Phlopp]

If a Pendolino ever does end up in the unfortunate position of having its raised pantograph in a neutral section when stopped (does it ever happen?), can the driver just lower that pantograph, raise the other, then move the train clear then swap pantographs back?

Yes.

Drivers are trained in relation to neutral sections and there's co-ordination between electrification and signalling, when electrification work is done, neutral sections are sensibly located to minimise the risk of a single pantograph vehicle becoming stranded.

In practical terms, neutral sections are kept away from areas where trains will be stopping - platforms and the ends of signalling sections and when it's unavoidable to place a neutral section in a compromised location, they're situated in positions where a driver can either apply a quick burst of power or ease of the brake to just clear the section before having to stop, so halfway along a platform rather than at the end, that sort of thing.

We also locate them in sensible locations so the momentary drop in acceleration doesn't provoke, as far as is possible, a dramatic drop in speed, so if the Bromsgrove electrification was going to need a new feeder at the bottom of the Lickey incline, we would place the neutral section at the top, where the gradient levels out, rather than half way up the incline, where the abrupt loss of power could be uncomfortable and with a freight train, could place excess strain on the couplers.

You also don't want to place a neutral section in a position where a slow moving train could come to a halt just past the neutral section and have to accelerate from a standing start again.

Ideally, you want them on a section of line which is level, where trains will be up to speed or have accelerated significantly and where there's absolutely no reason for a train to stop other than in an emergency.
--- old post above --- --- new post below ---

That assumes the escape has been detected!

And trains would still need to slow to a crawl to get into the Edinburgh branch, which is the one I use. At least if I'm on a Voyager I don't worry about losing power. It's the juxtaposition of two neutral sections so close to each other on such a low speed area that makes it so nail-biting. Do you know a train has ever got stuck there? I would find it very likely, although I suppose the Pendos are so long one of the pantographs is always under energized wire.

It's much rarer than you expect, AC drivers tend to be an attentive bunch when it comes to the OLE. They regularly report dislodged droppers or debris in the OLE and one really wonders how a driver could spot that at the sort of speeds they're doing.

 

[AM9]

... It's much rarer than you expect, AC drivers tend to be an attentive bunch when it comes to the OLE. They regularly report dislodged droppers or debris in the OLE and one really wonders how a driver could spot that at the sort of speeds they're doing.

If a driver does see some irregularity in the OLE that could result in a dewirement, does he have an emergency 'drop pantograph' button that could work fast enough to prevent damage if the contact is, say, two coach lengths behind him as might be typical for a four coach EMU?

 

[Philip Phlopp]

If a driver does see some irregularity in the OLE that could result in a dewirement, does he have an emergency 'drop pantograph' button that could work fast enough to prevent damage if the contact is, say, two coach lengths behind him as might be typical for a four coach EMU?

No emergency button, just the usual pan up/pan down. Pantographs drop relatively quickly - 3 to 4 seconds for a BR/BW unit typically.

 

[neilb62]

Okay lets try to put this to bed, as a 390 Driver who has been involved with them since the Old-Dalby days I'll stick my penny's worth in.
390 was always designed to run on the rear pan and during testing and in its early service days it did. It was then discovered that in just a couple of locations, Monument Lane near New St in the Up Direction and one other near Stockport IIRC there was a chance that when stopped at a certain signal the pantograph would be it the right position to create a crossfeed or similar between two OHL runs (nothing to do with neutrals but feeder stations). At first a 390 stop board was erected at the affected signals to guide the Driver to stop further than normal from the signal (the one at Monument Lane is still there) but it was then decided to run the fleet on the leading 'pan until the problem was 'bottomed'. This took longer than expected due to the 9 car extension programme ongoing at the time. Eventually the problems were all sorted and its pure coincidence that the rear pan was brought back into use during the bad winter of a few years ago.
Both Pans up? Yes it has happened although as far as I know only at Old-Dalby. It had no adverse affect on the train and it seems there was a glitch in the pan changeover programme that prevented one pan getting a 'down' signal before the other got the 'up' signal. This was tweaked and the Drivers Pantograph change over procedure slightly changed. Job done.
Front/Rear Pan Speeds. At the moment there are no speed restrictions in place with the front pan in use. The Brecknell-Willis pan if you notice has a box section lower arm and the aerofoils on the pan head are to counter the slipstream pushing on the box section either trying to force it up or down depending on direction of travel. I'm told that should we ever get to exceed 125mph in service then due to this slipstream effect the max permitted speed front pan raised would then be 125mph.
Thanks for reading.
Neil.

 

[Philip Phlopp]

I'm told that should we ever get to exceed 125mph in service then due to this slipstream effect the max permitted speed front pan raised would then be 125mph.
Thanks for reading.
Neil.

That's a really interesting crumb of information. Thanks.

 

[driver_m]

Yes.

Drivers are trained in relation to neutral sections and there's co-ordination between electrification and signalling, when electrification work is done, neutral sections are sensibly located to minimise the risk of a single pantograph vehicle becoming stranded.

In practical terms, neutral sections are kept away from areas where trains will be stopping - platforms and the ends of signalling sections and when it's unavoidable to place a neutral section in a compromised location, they're situated in positions where a driver can either apply a quick burst of power or ease of the brake to just clear the section before having to stop, so halfway along a platform rather than at the end, that sort of thing.

We also locate them in sensible locations so the momentary drop in acceleration doesn't provoke, as far as is possible, a dramatic drop in speed, so if the Bromsgrove electrification was going to need a new feeder at the bottom of the Lickey incline, we would place the neutral section at the top, where the gradient levels out, rather than half way up the incline, where the abrupt loss of power could be uncomfortable and with a freight train, could place excess strain on the couplers.

Ahem....Kidsgrove...cough...cough ....

Not the best location for a neutral, you'd have to admit!

 

[ComUtoR]

Ideally, you want them on a section of line which is level, where trains will be up to speed or have accelerated significantly and where there's absolutely no reason for a train to stop other than in an emergency.

We were taught that they are placed on a down gradient so that if you did manage to come to a stop you can gravitate out. I think its even mentioned in my traction manual too.

AC drivers tend to be an attentive bunch when it comes to the OLE.

Us DC boys are pretty awesome too

They regularly report dislodged droppers or debris in the OLE and one really wonders how a driver could spot that at the sort of speeds they're doing.

It's surprisingly easy if I'm honest. Whilst its not something I am directly looking for. The OLE is very clear and clean infrastructure. You tend to notice the slightest change. The worst I've seen is a plastic bag and that was taken very seriously.

 

[neilb62]

From a Drivers point of view the location of some of the newer OHNS on the WCML beggar belief!


Sent from my iPhone using fat fingers and a squint.

 

[Philip Phlopp]

We were taught that they are placed on a down gradient so that if you did manage to come to a stop you can gravitate out. I think its even mentioned in my traction manual too.

If you can put them on a slight gradient, that's perfect, but you've got to take care not to have a situation where stock can roll into the neutral section. It's all starting to get fairly academic now, with so many units running in multiple and more stock having pairs of pantographs
--- old post above --- --- new post below ---

Ahem....Kidsgrove...cough...cough ....

Not the best location for a neutral, you'd have to admit!

Kidsgrove was a result of DVTs if I remember correctly - the signal and neutral section was fine when a loco was always leading, but when the loco was pushing, it all went horribly wrong.

That's part of the problem when designing neutral sections today - keeping neutral sections and signalling sections clear with a more varied length of stock and position of the pantograph.