Changing Power

The train in your scenario must have both conductor shoes and a pantograph. Therefore, the train always has both AC and 3DC capabilities. You don't need to change the traction type selected for the train to keep moving, you just need to set it up with both traction types.

" said:

The train in your scenario must have both conductor shoes and a pantograph. Therefore, the train always has both AC and 3DC capabilities. You don't need to change the traction type selected for the train to keep moving, you just need to set it up with both traction types.

however in that case it would need to stop to raise/lower the pantograph.

The train in your scenario must have both conductor shoes and a pantograph. Therefore, the train always has both AC and 3DC capabilities. You don't need to change the traction type selected for the train to keep moving, you just need to set it up with both traction types.

Ah, so there's no way to go from 3DC only to AC only? Righto.

" said:

The train in your scenario must have both conductor shoes and a pantograph. Therefore, the train always has both AC and 3DC capabilities. You don't need to change the traction type selected for the train to keep moving, you just need to set it up with both traction types.

Ah, so there's no way to go from 3DC only to AC only? Righto.

Well, my reasoning is that the signaller shouldn't be able to try and route the train over AC-only tracks before the switchover has occurred, or over DC-only after. If that were to occur, I would indeed expect the signaller to have to intervene when the driver phones in to confirm the route and required traction power change.

If a train is fitted with both AC/DC then why wouldn't the signaller route it over tracks that are fitted with either. Just because a train has changed over once, doesn't mean it won't change over again, and to be honest I can't think of the top of my head anywhere where this may be an issue

Using Farringdon as an example as in the West Hampstead sim you set both power types in the train types folder to both AC/3DC. But the train whether it is booked to stop at Farringdon or not will stop to raise or drop the pantograph so the alternate power supply then powers the traction unit. I think the only time it can be done withour stopping is in the case of Cl.73 electro diesels where if the loco is running on diesel the shoes can be dropped to pick up the DC traction supply, but whther the loco has to be stationary for this to happen I can't confirm. I'm sure 'Crompton' would be able to give a more precise answer on that, but whenever I've spoken to Hither Green men in the past they've never mentioned you have to stop. There is a split second when changing from AC to DC or DC to AC when the unit is 'dead' before the electrical power system kicks in again running off the alternative source.

" said:

Using Farringdon as an example as in the West Hampstead sim you set both power types in the train types folder to both AC/3DC. But the train whether it is booked to stop at Farringdon or not will stop to raise or drop the pantograph so the alternate power supply then powers the traction unit. I think the only time it can be done withour stopping is in the case of Cl.73 electro diesels where if the loco is running on diesel the shoes can be dropped to pick up the DC traction supply, but whther the loco has to be stationary for this to happen I can't confirm. I'm sure 'Crompton' would be able to give a more precise answer on that, but whenever I've spoken to Hither Green men in the past they've never mentioned you have to stop. There is a split second when changing from AC to DC or DC to AC when the unit is 'dead' before the electrical power system kicks in again running off the alternative source.

I believe the 73s can change over on the move. When I was learning Acton Wells we had a regular MGR train from Tyne Yard to Ridham Dock; it had changed engines at Brent Junction (Midland line just north of Cricklewood) and was brought forward by a pair of 73s. I was told of an incident where they'd changed over power systems a bit early and the shoes had dropped before they were all on the juice rails. Because the line from Cricklewood wasn't electrified there were no run-on ramps from that direction, nor current rail gaps that would have allowed them to run in properly. Consequently the juice rail was knocked right off the insulating pots...

Class 373s can certainly change over whilst moving, although I believe there was at least one let's-demolish-Sandling-footbridge incident. Not sure if any ever had their shoes knocked off heading the other way.

But I notice they removed the shoes pretty quickly once HS1 opened throughout to St Pancras!

Going slightly more off topic, all the early BR A.C. electric classes were dual voltage with automatic changeover triggered by lineside equipment, albeit with power supplied through the same pantographs onboth voltages.

That was phased out after the changeover gear on the Class 303 turned out to be disastrously unreliable, causing several on-train fires.

" said:

But I notice they removed the shoes pretty quickly once HS1 opened throughout to St Pancras!

I thought they removed them because it was one less piece of kit to maintain.