Two pantographs in use.

[themiller]

I’ve just checked some photos of the LNER EF1 locos underway and all show 2 pantographs up and, in one photo, you can see twin conductor wires.

 

[bahnause]

SBB's RABe514s operate with two raised pantographs. The two halves of the train are not electrically connected on the high-voltage side. With four units, 8 pantographs are then lifted. However, they normally run with a maximum of three units.

 

[AM9]

SBB's RABe514s operate with two raised pantographs. The two halves of the train are not electrically connected on the high-voltage side. With four units, 8 pantographs are then lifted. However, they normally run with a maximum of three units.

They are also suburban units with a relatively low maximum speed (140km/h), so are unlikely to disturb the OLE stability too much. Apart from the fact that they only have motors in the end cars per unit so that a 16kV line doen't need to pass through the trailers, they functionally have a similar traction supply configuration to the UK classes 345 and 700.

 

[Richard Scott]

That's what I've heard as well. 16 ⅔ Hz was chosen as a compromise that would work fine, the motors could run on it and the voltage could be reduced onboard. Early railway electrification in Sweden actually used 15 Hz, but the frequency was later increased to 16 ⅔ Hz.

That's why you in general see 25 kV 50 Hz in countries that started electrifying late. Like Finland (1960s), Denmark (1980s), Portugal (1950s) or the UK.

It was used so DC motors could run on it without rectification, however at 50Hz the arcing between brushes and commutator was unacceptable but was within an acceptable limit at 16.7Hz.
Basically used the advantage of a higher voltage supply but without the need to rectify to DC.
Just to add a bit about two contact wires being used, have often seen that on 3000V lines as well. Definitely seen it in Italy and fairly sure in Poland too.

 

[jfollows]

Interesting, I wonder if the electrical schematics for those locos still exist somewhere.

https://www.railwaysarchive.co.uk/documents/MetroVickers_MSWLocos1954.pdf may be a good start

 

[FormerBritInMe]

In the USA, the only main line railways that operated with lower voltage DC OHLE electrification were the Milwaukee Road (3000 VDC) and the Chicago South Shore and South Bend. Only the latter is still electrified at 1500 VDC and is primarily a suburban commuter railway although it still runs freight but since 1981 this has been all Diesel powered. I have not seen any photos of dual pantographs being used. These lines used the famous "Little Joe" 2-D+D-2 electrics originally built for the Soviet Union but not shipped there due to worsening relations as a result of the Cold War. The locos were regauged to 1435mm standard gauge and in the case of the South Shore locomotives, converted to run at 1500V.

Analogous to the German and Swiss use of 15KV 16.5 Hz, much of the legacy US AC electrification was built as 11KV 25 Hz for similar reasons, to allow operation with series wound DC traction motors which was the technology at the time. The original New Haven RR electrification (New Rochelle to New Haven) has since been converted to 12.5 KV 60Hz but the original 25Hz electrification remains from New York to Washington plus suburban operations in the Philadelphia area.

 

[nwales58]

Just to add a bit about two contact wires being used, have often seen that on 3000V lines as well. Definitely seen it in Italy ...

Though, if you are old enough, that might have been two slightly wider-spaced contact wires for the 3 phase AC lines in the north of Italy using two current collectors side by side. They were subsequently converted to DC. There was a short line 3 phase freight operation in Spain down to Almeria but it was no longer electric when I tried to find it in 1974.

 

[Richard Scott]

Though, if you are old enough, that might have been two slightly wider-spaced contact wires for the 3 phase AC lines in the north of Italy using two current collectors side by side. They were subsequently converted to DC. There was a short line 3 phase freight operation in Spain down to Almeria but it was no longer electric when I tried to find it in 1974.

No, I'm not that old!!! First went to Italy in 2002 and only started doing trains there in 2015 so definitely standard 3000V! Looking through few pictures I have from this year, twin wire in Taranto and Firenze Rifredi.

 

[Gordon]

SNCF locos thus fitted commonly raise both pantographs at slower speeds / starting a heavy train from a stand - even on bi-voltage locos where one of the two pantographs is supposed to be for ac and one for dc.

As an example here is a (though I say it myself) a rather superb shot I took at Beaune in June 2022. Both locos are bi-current 22200s

 

[popeter45]

SNCF locos thus fitted commonly raise both pantographs at slower speeds / starting a heavy train from a stand - even on bi-voltage locos where one of the two pantographs is supposed to be for ac and one for dc.

As an example here is a (though I say it myself) a rather superb shot I took at Beaune in June 2022. Both locos are bi-current 22200s

dispite being same family as the NS locomotives suprising they have a diffrent pantograph layout (NS ones point either direction while SNCF one here has them facing same direction)

 

[Richard Scott]

dispite being same family as the NS locomotives suprising they have a diffrent pantograph layout (NS ones point either direction while SNCF one here has them facing same direction)

The 22200s have them both in same direction (and either can be used for dc or ac operation) whereas 7200s have them in opposite directions, similar to NS 1600s and 1700s. Think 15000s only have one pantograph but happy to be corrected on this one.

 

[DanielB]

whereas 7200s have them in opposite directions, similar to NS 1600s and 1700s.

Which makes sense as the prototype locomotive for the SNCF BB 7200 also was the prototype for the NS 1600s. With that French prototype various trials have been done in the Netherlands which after some small adaptions resulted in the order for the class 1600.

 

[Route115?]

Is there a limit to the maximum amount of current that a pantograph can handle? Obviously a train on a 1500V system will draw (around) ten times a much current as one on a 15kV system (not that I'm an electrical engineer).

 

[Bemined]

In the Netherlands there is a limit per train, 4000A on most lines, lower on some secondary lines (for example Zwolle - Emmen 2500A and Leiden - Woerden 3200A). Typically trains drawing this much current will have two pantographs in use though.

 

[Gordon]

Think 15000s only have one pantograph but happy to be corrected on this one.

Yes that is correct, BB15000 (25kV ac only) have one single arm pantograph, elbow inwards, at number 1 end.

In case anyone reading is not aware, there is logic to the numbering system as well. In the 1970s and 80s SNCF's standardisation allowed for class numbers to work on a 'add the numbers together' basis, as follows:

ac loco class number + dc loco class number = dual system loco class number

so for the electric broken nose B-Bs you have:

15000 (ac) + 7200 (dc) = 22200 (dual)

This is why BB22200 class should always be quoted as 22200 and not the erroneous (but commonly see written) 22000

 

[MarcVD]

15000 (ac) + 7200 (dc) = 22200 (dual)

similarly, cc6500 + cc14500 = cc21000
But the cc14000 remained a project and never materialized.

 

[43096]

similarly, cc6500 + cc14500 = cc21000
But the cc14000 remained a project and never materialized.

And also...
BB9200 + BB16000 = BB25200
BB8500 + BB17000 = BB25500

 

[Richard Scott]

similarly, cc6500 + cc14500 = cc21000
But the cc14000 remained a project and never materialized.

Also BB9200+BB16000=BB25200