GWR Class 800

[najaB]

I was simply trying to ask whether running in electric mode would make any difference to the screeching brakes or to the speeds below which the dynamic brakes did not operate.

Can't see why it would - I can't imagine drivers being much impressed if the braking characteristics changed on and off the wires.

 

[Taunton]

Don't forget that if the unit isn't able to put the regenerated electricity back into the OHL supply then it will automatically switch to rheostatic braking.

This must be just a feature of the British implementation of regen. Some overseas installations can accept all that is being regenerated, if it is too much (eg multiple trains regenerating and no trains drawing current) then any surplus is automatically burned off in large outside resistances at the substation.

 

[ainsworth74]

And how will that work where these trains aren't connected to OHLE?

 

[Bletchleyite]

And how will that work where these trains aren't connected to OHLE?

Rheostatic braking, i.e. "burning" it off as heat from roof-mounted resistors.

 

[ainsworth74]

Rheostatic braking, i.e. "burning" it off as heat from roof-mounted resistors.

Yes I know that my point was more that on an EMU where you're always going to be attached to OHLE you can look to put things back into the grid all the time (and make provision therefore for the grid to burn off any excess) but seeing as these units will not always been working as EMUs they need to have provision for dealing with things when away from OHLE.

 

[D365]

... but seeing as these units will not always been working as EMUs they need to have provision for dealing with things when away from OHLE.

Hence the roof-mounted resistor grids! Voyagers have them too. In fact I believe they are their primary weakness when it comes to the Dawlish line. However the IEPs have been specified to withstand the effects of saltwater spray.

 

[hwl]

Yes I know that my point was more that on an EMU where you're always going to be attached to OHLE you can look to put things back into the grid all the time (and make provision therefore for the grid to burn off any excess) but seeing as these units will not always been working as EMUs they need to have provision for dealing with things when away from OHLE.

"always" - Except it isn't always.

All southern region EMUs have had resistor grids mounted under the floor for the last 50+years as traditionally (until initially in some areas circa 2008 allowed limited regenerative braking) current couldn't be put back into the 3rd rail and even with regenerative braking, current is only allowed to be fed back into the 3rd rail between certain voltages above or below which rheostatic is used. Rheostatic saves huge amounts on not replacing brake pads especially on stopping services!

All AC units and I think most locos have rheostatic too as you need the guaranteed braking performance depending whether on not OHLE is tripped and if the voltage is in range as with 3rd rail DC (min and max voltages varies by OHLE infrastructure type).
The huge noise you get from a 91 for a couple of minutes after stopping at a station is the fans blowing air over the resistor grids... (TGVs, 373s and 374s (and all Velaros) also have resistor grids)

For example you can see 3 resistor grids under a 442 (not my photo) here, just under the guards door and slightly to the left:
http://www.southernelectric.org.uk/features/rolling-stock/442/img/cd442unf2.jpg

 

[43096]

"always" - Except it isn't always.

All southern region EMUs have had resistor grids mounted under the floor for the last 50+years as traditionally (until initially in some areas circa 2008 allowed limited regenerative braking) current couldn't be put back into the 3rd rail and even with regenerative braking, current is only allowed to be fed back into the 3rd rail between certain voltages above or below which rheostatic is used. Rheostatic saves huge amounts on not replacing brake pads especially on stopping services!

All AC units and I think most locos have rheostatic too as you need the guaranteed braking performance depending whether on not OHLE is tripped and if the voltage is in range as with 3rd rail DC (min and max voltages varies by OHLE infrastructure type).
The huge noise you get from a 91 for a couple of minutes after stopping at a station is the fans blowing air over the resistor grids... (TGVs, 373s and 374s (and all Velaros) also have resistor grids)

For example you can see 3 resistor grids under a 442 (not my photo) here, just under the guards door and slightly to the left:
http://www.southernelectric.org.uk/features/rolling-stock/442/img/cd442unf2.jpg

SR EMUs (including Class 442) did/do not not rheostatic braking. The resistors you can see are to do with the control system.

This on the SEG website gives more details: http://www.southernelectric.org.uk/features/rolling-stock/442/442ext03.html

 

[coppercapped]

A point of order!

Any traction that uses 25kV 50Hz ac as the line source and uses dc traction motors can only brake electrically if there are on-board braking resistors there being no on-board means to invert the generated current to 50Hz. If the traction uses variable frequency, variable voltage ac induction motors the power electronics can invert the feed generated by the motors to 50Hz ac and feed it back into the overhead. If the overhead is receptive then other trains can use the current and if not it will be fed back to the national grid.

With dc supply to the train, either third rail or overhead, a traction unit using electric braking can only feed power back to the supply if the supply is 'receptive' - that is its volts are lower than the normal supply maximum. As, to my knowledge, there are no sub-stations that can invert the dc back to ac and feed it to the grid, this means that if the current cannot be used by other trains being supplied by the same sub-station then it has to be either limited at source by the train using electric braking, or by over-voltage circuits in the sub-station feeding the 'excess' current to lineside banks of resistors. This was the solution adopted by the LNER for the Woodhead electrification as pre-war automatic current control was in its infancy.

 

[CP165]

For those interested I came across this video of 800101 departing Stevenage on AC.

https://www.youtube.com/watch?v=RIP3k8K5eHQ

Not my video, credit 'railnet'

There's also a 373 set at the beginning heading for scrap

 

[leomartin125]

For those interested I came across this video of 800101 departing Stevenage on AC.

https://www.youtube.com/watch?v=RIP3k8K5eHQ

Not my video, credit 'railnet'

There's also a 373 set at the beginning heading for scrap

Great video, haven't seen one depart using the wires yet so looks good. Glad they are testing the Azuma one on the ECML now, where it belongs.

 

[HSTEd]

I believe some units with the traditional Southern under-floor implementation of rheostatic brakes used the heat dispersed to help heat the vehicle interior during the winter.
Remember that AC units and locomotives also could not regenerate until relatively recently when reversable chopper type drives became widely used. A 'traditional' AC locomotive based on diode rectifiers cannot regenerate. This is one of the advantages of the universal motor type implementation used on German electric locomotives with their lower frequency supply power.

 

[SpacePhoenix]

For those interested I came across this video of 800101 departing Stevenage on AC.

https://www.youtube.com/watch?v=RIP3k8K5eHQ

Not my video, credit 'railnet'

There's also a 373 set at the beginning heading for scrap

Sounds different to what I expected - I'd expected it to sound similar to a Javelin

 

[fgwrich]

https://www.youtube.com/watch?time_continue=36&v=2oUY1t9x3uY

800101 on the ECML.

 

[Nym]

A coupe more pics from today at Merchant Park, Newton Aycliffe.

Looks like a depot today, in the picture of 4 IEP's, from left to right are:-

800003 GWR, 800101 VTEC, 4 carriages of either 801001 or 800301 (depending on the gossip mill) GWR and 800001 GWR. Also there is 1 uid carriage with no window stickers to id its identity.

Is it seriously still just me that thinks that high level double ended jumpers are a bad idea?

 

[leomartin125]

A coupe more pics from today at Merchant Park, Newton Aycliffe.

Looks like a depot today, in the picture of 4 IEP's, from left to right are:-

800003 GWR, 800101 VTEC, 4 carriages of either 801001 or 800301 (depending on the gossip mill) GWR and 800001 GWR. Also there is 1 uid carriage with no window stickers to id its identity.

There is no '801001'. As of yet, all IEP's are Class 800's. So it would be 800301, which is GWR's first 9 car IEP, which I guess was orginally going to be an 801, but has been manufactured as an 800 due to electrification delays.

 

[SpacePhoenix]

How long will it be now until the 800s are able to run in service on the ECML?

 

[RobShipway]

I am sure yesterday afternoon when travelling on a HST to Reading at about 1:30pm, that there was an IEP set within the Hitachi train shed at North Pole junction as the doors where open front and back.

 

[Dstock7080]

I am sure yesterday afternoon when travelling on a HST to Reading at about 1:30pm, that there was an IEP set within the Hitachi train shed at North Pole junction as the doors where open front and back.

Indeed, saw an IEP heading through Ealing Broadway UP fast at 0510 Friday morning.

 

[leomartin125]

I am sure yesterday afternoon when travelling on a HST to Reading at about 1:30pm, that there was an IEP set within the Hitachi train shed at North Pole junction as the doors where open front and back.

Wouldn't surprise me Robbie! It is an IEP Depot after all! I do believe a bunch of IEP's are now based at Stoke Gifford, it would appear that Friday night's test to Swindon from North Pole ended up stabling in Stoke Gifford once complete. Not sure there are any IEP's in there now, maybe there is one left.

 

[LNW-GW Joint]

how long will it be now until the 800s are able to run in service on the ecml?

"2018".

 

[D1009]

Yesterday there were 3 5 car class 800s visible at Stoke Gifford, two of which appeared to be coupled, the other was the green one.

 

[Devonman2014]

Starting Monday 31/10/16 for 5 nights there are a number of paths for 2xIEP (believe this is a double headed 1st into Devon) to be going Stoke Gifford to plymouth finishing Sat 05/11/16 in the early hours

Course some may not run !!!

The path from Stoke Gifford to Plymouth

http://www.realtimetrains.co.uk/train/K97131/2016/10/31/advanced

Then return to Newton Abbott as 2 paths below

http://www.realtimetrains.co.uk/train/K97132/2016/11/01/advanced

http://www.realtimetrains.co.uk/train/K97126/2016/11/01/advanced

Before its return from Plymouth to Stoke Gifford

http://www.realtimetrains.co.uk/train/K97128/2016/11/01/advanced

Maybe of interest to someone on the route....

 

[jopsuk]

What extent have the 800s covered now? They've been to Plymouth, have they been further? On the ECML, how far north have they gone so far?

 

[800001]

What extent have the 800s covered now? They've been to Plymouth, have they been further? On the ECML, how far north have they gone so far?

Think it just as far as Darlington, don't think they have been further north.
--- old post above --- --- new post below ---

There is no '801001'. As of yet, all IEP's are Class 800's. So it would be 800301, which is GWR's first 9 car IEP, which I guess was orginally going to be an 801, but has been manufactured as an 800 due to electrification delays.

Another 3 carriages for this set now sat out side, next to the other 4.

 

[Devonman2014]

What extent have the 800s covered now? They've been to Plymouth, have they been further? On the ECML, how far north have they gone so far?

To best of my knowledge they have not ventured further south than Plymouth.

 

[SpacePhoenix]

Could they get run to Weymouth (diesel mode) on the route of the Weymouth-Bristol, even if it's just for mileage accumulation?

 

[D1009]

Could they get run to Weymouth (diesel mode) on the route of the Weymouth-Bristol, even if it's just for mileage accumulation?

Why would they want to do that?

 

[SpacePhoenix]

Why would they want to do that?

Well GWR use HSTs down to Weymouth in the summer, once their HSTs start to leave they might want to use a IEP on the route

 

[RobShipway]

Could they get run to Weymouth (diesel mode) on the route of the Weymouth-Bristol, even if it's just for mileage accumulation?

If anything they would more likely be run to Penzance than Weymouth as at some point in the future I suspect that you will be haing class 802's running to to Penzance, whereas I do not see any class 800's running to Weymouth.