IET class 801 Paddington - Taunton: when does the switch to diesel power actually begin?

[D89 HAC]

I had a Paddington to Paignton run a week or two ago - my first journey on one of these. It was a 9 car unit. I had a stopwatch with me and ended up logging the running from Reading to Exeter. Talking to the on board train manager towards Paignton, he thought the pantograph came down at Newbury. Does anyone know if there's a definitive place the switch to diesel would occur on such a service?

 

[Energy]

Not an 801 but an 802, similar but the 802s have more diesel engines.

 

[83A]

I beleive the wires end just past Newbury so I think that is correct.

 

[Wilts Wanderer]

I think the pan actually comes down approaching Newbury Racecourse (if non-stopping) and the wires run out just west of Newbury station. There has to be time for the train to stop if the pan is stuck in the raised position without running off the end of the wires and causing damage.

 

[Sion John]

Not an 801 but an 802, similar but the 802s have more diesel engines.

GWR just have 800s and 802s because 801s are just for LNER because 801s are just electric but has 1 engine just in case

 

[D89 HAC]

I think the pan actually comes down approaching Newbury Racecourse (if non-stopping) and the wires run out just west of Newbury station. There has to be time for the train to stop if the pan is stuck in the raised position without running off the end of the wires and causing damage.

The service stopped at Newbury so if the wires go as far as the racecourse that all makes sense, Newbury it must have been. Many thanks.

Not an 801 but an 802, similar but the 802s have more diesel engines.

You're quite right Energy, it was unit 802 102. Cheers.

 

[gallafent]

the 802s have more diesel engines

I don't think that's true.

 

[hexagon789]

I don't think that's true.

Indeed it isn't, they have the same number - three in a 5-car and five in a 9-car.

 

[Energy]

Indeed it isn't, they have the same number - three in a 5-car and five in a 9-car.

801s only have 1 diesel engine for backup power in case of OHLE failure.

 

[hexagon789]

801s only have 1 diesel engine for backup power in case of OHLE failure.

Yes, but I assumed we were talking about 802s compared to 800s as GWR have no 801s and 801s are electric only in normal service.

 

[Rob F]

The thread title mentions 801s, so I assume the OP was mistaken.

 

[plugwash]

GWR just have 800s and 802s because 801s are just for LNER because 801s are just electric but has 1 engine just in case

Originally the intercity express program was supposed to suply 801s for both east coast and great western services. However cutbacks to the great western electrification program meant that the orders for GWR 801s were changed to 800s.

The 802s were ordered outside the intercity express program, IIRC they originally had a higher power limit on the diesel engines than the 800s but later the 800s were reprogrammed to have the same limits as the 802s.

 

[Thatcham Xing]

The pan down area is at Kennet Viaduct, a bridge just at the start of Newbury Racecourse's long straight (look to your left from the train) when heading west.

I haven't checked exactly but that must be about 1.5 miles before the wires actually run out west of Newbury Station.

Linespeed changes from 100 to 110 at about the same point - for trains not stopping at Newbury and passing through on the centre tracks.

 

[David Goddard]

The 801s originally ordered for GWR were changed to 800s at the build stage and are what we now see as 800/3s
Yes wires run out West of Newbury so if not calling will drop the pan as above. Kennett viaduct is at mp51.3, with wires as far as about 53.5

 

[Clarence Yard]

Originally the intercity express program was supposed to suply 801s for both east coast and great western services. However cutbacks to the great western electrification program meant that the orders for GWR 801s were changed to 800s.

The 802s were ordered outside the intercity express program, IIRC they originally had a higher power limit on the diesel engines than the 800s but later the 800s were reprogrammed to have the same limits as the 802s.

No, the vast majority of the GWR 800 fleet were delivered with the 700kw rating installed. Only 800001-4 were built with the 565kw rating installed and they were quickly altered with the help of a laptop, way before entering passenger service.

 

[gallafent]

Yes, but I assumed we were talking about 802s compared to 800s as GWR have no 801s and 801s are electric only in normal service.

I made that mistake too since on GWR there are only 800s and 802s, no 801s! D'oh, perils of running on autopilot! … so yes, 800s and 802s have the same number of engines but 801s just have the one emergency one! Apologies for the thread noise!

 

[59CosG95]

I seem to remember that the 802s have larger fuel tanks than the 800s, and that their roof-borne equipment is better defended against sea spray over Dawlish - but that might just be me.

 

[Wyrleybart]

I seem to remember that the 802s have larger fuel tanks than the 800s, and that their roof-borne equipment is better defended against sea spray over Dawlish - but that might just be me.

Pretty sure "Clarence Yard" has previously stated that under the floor 800s and 802s are now identical, although perhaps still not the same version of software.
It is on the roof that things are different. 800s were expected to spend the majority of time under the OLE and using regen brakes. The 802s were designed to operate away from OLE for much longer periods so were given larger rooftop rheostatic brake grids as they wouldn't be feeding much back into the OLE west of Didcot, Newbury, Chippenham or Cardiff.

 

[irish_rail]

Don't forget drivers can change from electric to diesel pretty much where ever we like, and lots of us pan down approaching Thatcham as there is often a double yellow signal there which increases workload somewhat , hence going over to diesl that bit earlier so one less thing to have to worry about.

 

[hexagon789]

I made that mistake too since on GWR there are only 800s and 802s, no 801s! D'oh, perils of running on autopilot! … so yes, 800s and 802s have the same number of engines but 801s just have the one emergency one! Apologies for the thread noise!

No worries, just a small misunderstanding

 

[AM9]

Don't forget drivers can change from electric to diesel pretty much where ever we like, and lots of us pan down approaching Thatcham as there is often a double yellow signal there which increases workload somewhat , hence going over to diesl that bit earlier so one less thing to have to worry about.

Is it not possible to have a track magnet, (similar to the type used to open the contactors when approaching a neutral section) located an appropriate distance ahead of the last acceptable pantograph drop to take that load off the driver?

 

[Clarence Yard]

I seem to remember that the 802s have larger fuel tanks than the 800s, and that their roof-borne equipment is better defended against sea spray over Dawlish - but that might just be me.

The 800s and 802s have exactly the same (1550L) fuel tanks and have had since entry into passenger service. 800004 was the first one to get the larger fuel tanks and that was done for the fuel test runs when it was still a test unit. 800005 onwards had them from new and test units 800001-3 were retrofitted with the 1550L tanks before entering passenger service.

The 800 and 802 units have the same engine software and have used identical 700kw settings since entry into passenger service. The only variation has been the repeated general unit software upgrade programmes, which tend to be done one class at a time.

The larger roof mounted equipment fitted on the 802 fleet is indeed designed to be more Dawlish resistant but a heavy wave will still short them out temporarily until the salt water swilling around on the roof has drained away and the engines can be reset.

 

[hexagon789]

Is it not possible to have a track magnet, (similar to the type used to open the contactors when approaching a neutral section) located an appropriate distance ahead of the last acceptable pantograph drop to take that load off the driver?

I thought there was an auto-changeover system fitted on the GWML but it was isolated and thus changes are manual atm?

 

[Wilts Wanderer]

I thought there was an auto-changeover system fitted on the GWML but it was isolated and thus changes are manual atm?

I think the operational considerations for auto-changeover are quite complex. Newbury is a good example, as if you had a train terminating from the London direction, you wouldn’t want to drop the pan approaching Racecourse as you’d be staying on electric for the return journey.

 

[irish_rail]

I thought there was an auto-changeover system fitted on the GWML but it was isolated and thus changes are manual atm?

Yes the Apco as it is known is currently isolated but eventually it will do as you say and do the tractiom changeover automatically. Think it was supposed to come in late 2018 but we are still waiting! Personally I don't really want anything that takes a job away from the driver but I'm sure plenty more money will be thrown at it to get it up and running one day.....

 

[hexagon789]

Yes the Apco as it is known is currently isolated but eventually it will do as you say and do the tractiom changeover automatically. Think it was supposed to come in late 2018 but we are still waiting! Personally I don't really want anything that takes a job away from the driver but I'm sure plenty more money will be thrown at it to get it up and running one day.....

I presume there will still be the ability to do manual changeovers in emergencies or if the "apco" fails for some reason, in other words it provides for automatic changeovers but doesn't entirely supercede manual oned

 

[D89 HAC]

The 801s originally ordered for GWR were changed to 800s at the build stage and are what we now see as 800/3s
Yes wires run out West of Newbury so if not calling will drop the pan as above. Kennett viaduct is at mp51.3, with wires as far as about 53.5

Thanks David- very helpful.

 

[Railcar]

Arriving at Paddington on a journey from Newton Abbott in September, I thanked the driver for a smooth ride. He confirmed that he had put the pan up at Thatcham.

 

[Thatcham Xing]

He confirmed that he had put the pan up at Thatcham.

I thought pan-up was supposed to be done in an area where the OLE has been modified (strengthened?) for that purpose. As far as I know the pan-up area on the B&H is at Kennet Viaduct (the same place as pan-down in the down direction)? There are line-side signs that indicate it in the area of the new(ish) overbridge to Newbury Racecourse.

 

[59CosG95]

I thought pan-up was supposed to be done in an area where the OLE has been modified (strengthened?) for that purpose. As far as I know the pan-up area on the B&H is at Kennet Viaduct (the same place as pan-down in the down direction)? There are line-side signs that indicate it in the area of the new(ish) overbridge to Newbury Racecourse.

Not so, AFAIK. Automatic Pan Change Over (APCO) is undertaken when the train passes a set of balises which activate a circuit triggering the raise of said pantograph(s), but this can be overridden manually in the event of a fault. As S1 OLE is at a higher tension across the board than other ranges (13kN catenary, 16.5kN in contact AIUI) the pan change can be done on the fly anywhere.