EMU Pantograph Positioning

[306024]

Just thought this was such a good picture it needed repeating

Reminds me of one day as a unit controller one of these was on the front of a Liverpool St to Clacton train. Suddenly got a phone call from the Clacton LDC chairman (drivers staff rep) asking why? Apparently there was a gentleman’s agreement that this was to be avoided as it didn’t give as smooth a ride for the driver as the other 309 types. All news to me, but we swapped it over on arrival at Clacton and a young unit controller earned a few brownie points with the drivers.

 

[Bald Rick]

Umm, HS1 copes quite well with 2 pans up at 125 mph+ (Javelins) & 180 mph E-Stars.
The OHLE (Standard French Hi-Speed) seems to be quite simple, with closer mast spacing than elsewhere in the UK, but simple catenary.

Sorry, yes, I meant on NR infrastructure. On High Speed lines the tension is higher and the contact wire is level, and therefore there is little issue with wave propagation in the contact wire (which is one of the key problems).

 

[Bald Rick]

If there was a need to run very high power traction to haul heavy trains through a mountain area, and we had all energy from hydro projects, it would be easy to provide the infrastructurenecessary for them to operate.



And the tension is quite high which means that standing waves are of lower amplitude and of shorter wavelength. Simple catenary haas been the standard in the UK since the '60s. The lines converted from 1500VDC, e.g. GEML, had compound catenary OLE as it was thought to dampen pantograph oscillations, which at the time of introduction were much heavier diamond pattern types. The additional wire in compound also helped to reduce voltage losses. The last compound wiring was removed a few years ago when the GEML OLE was refurbished with F&F parts, similar to those used on the GWML.
Here is a picture of Ilford station, probably in the '90s when 25kV had been in use for over 30 years. Note the compound catenary:

and here is a more recent picture showing the updated OLE with the F&F registration parts installed somewhere near BOW by the looks of it:

Despite this picture showing the transition from one length of catenary to the next giving eight sets for four tracks, each catenary is of simple type and has a minimal HV footprint.

There is, I think, still some compound catenary on the GEML around Stratford. It was certainly there not long before Christmas.

 

[AM9]

There is, I think, still some compound catenary on the GEML around Stratford. It was certainly there not long before Christmas.

Presumably not subjected to anything above about 60-70 mph.

 

[AM9]

Some countries seem to still be using stitched catenary designs, - in the case of Germany, for high-speed lines as well as classic. Are there any characteristics about that which has prevented deployment in the UK, even as a trial?

 

[306024]

Presumably not subjected to anything above about 60-70 mph.

Speed on the up main through Stratford for passenger trains is 80mph, 70mph on the down main, less on the electric lines where the signal spacing is much closer. Stratford is the last big area to be fully rewired following the work at Forest Gate Jn over Christmas. Finding a way to do this whilst minimising the disruption to both passenger and freight services is taxing the minds of various OHLE engineers.

 

[driver_m]

There's still compound catenary from Weaver Junction to Edge Hill. It's not continuous, but there is plenty of it in the Liverpool area, there's still one or two sections elsewhere on slow lines on the rest of the WCML I thought they were supposed to be getting rid of it, after one of my Euston Colleagues got zapped with it at Sutton Weaver?

 

[whhistle]

On 390s The pans are the opposite way round so the rear one is always the aerodynamically the best way round for the direction of travel. I assume the 395s are the same

In a similar vein, the Pendos always use the rear one in case something rips it off. There will only be a few coaches of damage rather than nearly a whole set.
If the front one is being used, the rear one has a fault.

 

[K.o.R]

Umm, HS1 copes quite well with 2 pans up at 125 mph+ (Javelins) & 180 mph E-Stars.
The OHLE (Standard French Hi-Speed) seems to be quite simple, with closer mast spacing than elsewhere in the UK, but simple catenary.

This was something that really confused me when watching footage of HS1. The OLE seems very simple--nothing like the massive structures on the GWML--and yet it's fine for way faster than 140mph.

 

[AM9]

This was something that really confused me when watching footage of HS1. The OLE seems very simple--nothing like the massive structures on the GWML--and yet it's fine for way faster than 140mph.

That's because registration will be more positive and resonance at a higher frequency with shorter spans.
The GWML probably doesn't have enough space in the formation to have virtually all single-track cantiliver supports, nor full portals.

 

[Taunton]

For those concerned about more than one pantograph .

 

[delticdave]

For those concerned about more than one pantograph .View attachment 58020

Nice....

When the EM2's went to NS, they were fitted with heavy duty single arm pantographs with twin "pickup heads?" so they only had to use the front pantograph for starting, usually dropping it at 30 km/h.
NS use single catenary but with twin contact wires, + extra supply cables on busy routes to keep the voltage drop down.

 

[driver_m]

There's a pic on twitter today at Patchway showing Solid OLE. How would pans behave on that?!! (I know its only a small section, I'd seen this rail based OLE in Spain too in Malaga Underground Station on a much longer section.) Sorry I dont know how to link a pic of it .

 

[AM9]

There's a pic on twitter today at Patchway showing Solid OLE. How would pans behave on that?!! (I know its only a small section, I'd seen this rail based OLE in Spain too in Malaga Underground Station on a much longer section.) Sorry I dont know how to link a pic of it .

That's what is used on the Thameslink core. Clearly not for speed reasons, more as a low through-life option despite the higher initial capital cost. There will also be the F&F 'conductor bar' used in the Severn Tunnel.
Pantographs just see it as a very firmly mounted OLE conductor with little or no lateral of vertical movement. It comprises a metal channel with the normal conductor wire passing through a cavity.

 

[Chris125]

This is presumably the picture in question: https://twitter.com/NoelDolphin/status/1084861500248997888

This open-air gap uses the same conductor bar system as the tunnels either side, avoiding the need for an awkward 160m section of conventional tensioned wiring.

 

[James James]

Thanks everyone, particularly AM9, for the replies.

So does having multiple pantographs up at once have nothing to do with the power needed? I always assumed that the Pendolinos would need both pantographs up to operate at the 140mph design speed but clearly that's not the reason for the second pantograph (and likewise on the 395s, which also have the pantograph at the rear of the driving car).

In high-voltage AC countries: yes, no relationship between power and pantograph usage.

But in low-voltage DC that seems to be different: at least in Poland, where they operate with 3kV DC, two pantographs are used when at low speeds / in stations, with the pantograph being dropped once the train is moving. (I'm not sure what the exact threshhold is, mind you. I just know it's a thing.) One aspect is apparently to avoid the pantograph welding itself to the catenary - I'm not sure how reliable my information is though...


Also of likely interest to this thread are the new'ish RABE 502 in Switzerland. They're double decker EMU's with top-level gangway (i.e. the top floor is continuous throughout the train, whereas most double deckers have a mezzanine deck at the carriage ends and gangways at UIC height). They had to be built with Pantograph's at the very end of each unit because of that gangway.

These trains have been eternally delayed and still aren't reliable (thanks Bombardier), so it's hard to actually spot them in real life usage. But it does seem like they use the rear pantograph for single unit usage - but they might be using the front pantograph for the front unit when 2 units are coupled together. Which kinda makes sense from the perspective of avoiding excessive dust falling onto the windscreen of the second unit - but it would certainly be odd to see a pantograph up at the front of a 16-carriage train going 200km/h...

 

[edwin_m]

That's what is used on the Thameslink core. Clearly not for speed reasons, more as a low through-life option despite the higher initial capital cost. There will also be the F&F 'conductor bar' used in the Severn Tunnel.
Pantographs just see it as a very firmly mounted OLE conductor with little or no lateral of vertical movement. It comprises a metal channel with the normal conductor wire passing through a cavity.

I believe it zigzags across the track as normal OLE does, so that the pantograph wears evenly rather than creating a groove that might cause a dewirement.

 

[AM9]

I believe it zigzags across the track as normal OLE does, so that the pantograph wears evenly rather than creating a groove that might cause a dewirement.

Actually, I should have worded that in a less ambiguous way. What I meant was that it's registration is more firmly fixed and not subject degree of movement as is the case with conventional conductor wire OLE. Of course it has the same lateral stagger as any other systems to spread the wear across the carbon contact strips on the top of the pantograph. In areas of reduced clearances, the use of a rigid conductor bar can remove the need for floor lowering or increasing the roof height. Bar systems also reduce the maintenance requirements.