Bi mode Flirts - Can they change power types on the move?

[paulkidger]

I was waiting at Haughley crossing where the non electrified line from Cambridge and Peterborough joins the electrified GE main line from London to Norwich, a 755 dual powered unit came off the branch on its way to ipswich. I noticed that the pan was up. I thought that this transition from diesel to OH electric could only take place at the next stop..Stowmarket. Does anyone know whether changing whilst on the move is an acceptable practice?

 

[DanNCL]

I was waiting at Haughley crossing where the non electrified line from Cambridge and Peterborough joins the electrified GE main line from London to Norwich, a 755 dual powered unit came off the branch on its way to ipswich. I noticed that the pan was up. I thought that this transition from diesel to OH electric could only take place at the next stop..Stowmarket. Does anyone know whether changing whilst on the move is an acceptable practice?

The Flirts are capable of changing whilst on the move (as are Hitachi 800s and 802s for that matter), but it can only be done on the move in specifically authorised locations, I'm not sure where those are located on the Greater Anglia network. I don't know the technical term for it, but I think the wires have to be reinforced in locations where bi mode trains are expected to raise the pantograph whilst on the move.

 

[ainsworth74]

I don't know the technical term for it, but I think the wires have to be reinforced in locations where bi mode trains are expected to raise the pantograph whilst on the move.

As far as I'm aware the wires are no different to anywhere else but they are subject to more regular inspections.

 

[Elecman]

The catenary MAY be at increased tension to reduce the uplift of the wire from a moving pan hitting it when raised.

 

[paulkidger]

Thanks for the replies. The OH does extend for a short distance on the Cambridge/Peterborough branch as is often the case at such junctions. I am wondering whether this was an unauthorised switch over on the run. It would seem to be advantageous to be able to do such a changeover bearing in mind that the junction is at the top of Haughley bank; a 1:99 rise from the Gipping Valley. In order to save on diesel power the trains could be on elec up the bank and regenerate on the way down.

 

[dk1]

We are not permitted to changeover power on the move.

 

[ac6000cw]

Could the 755 have been stopped at the signal protecting the junction and hence be able to do a stationary changeover under the overrun/overlap OHLE run on the approach to it?

 

[dk1]

Could the 755 have been stopped at the signal protecting the junction and hence be able to do a stationary changeover under the overrun/overlap OHLE run on the approach to it?

Depends whether or not it’s in the pan protection zone. Anything the wrong side of it would cause the pantograph to drop & an emergency brake application. Power changeovers in an area like that would be frowned upon especially after a recent incident which caused tens of thousands of pounds worth of damage. Rules have been tightened up quite substantially.

 

[Shwam3]

There will eventually be a dynamic power changeover site in both directions for Haughley Junction but it doesn't exist yet (in fact there are none at all on the GA network yet).

Depends whether or not it’s in the pan protection zone.

The pantograph protection zone starts & ends at Haughley AHB crossing so it would intervene there, also the wires don't extend to the protecting signal on the branch.

 

[dk1]

There will eventually be a dynamic power changeover site in both directions for Haughley Junction but it doesn't exist yet (in fact there are none at all on the GA network yet).


The pantograph protection zone starts & ends at Haughley AHB crossing so it would intervene there, also the wires don't extend to the protecting signal on the branch.

I think many of us have found out where it ends at Ely North Jcn & Between Crown Point & Whitlingham lol.

 

[paulkidger]

Forgive my ignorance but I presume that the Protection Zone is a section of isolated and non-energised O/H which causes the safety systems to operate in response to the 'No-volt' condition. Likewise the Dynamic Power Changeover ...I presume that this will be an approved section where the transition between O/H power collection and on board power generation can take place.

 

[dk1]

Forgive my ignorance but I presume that the Protection Zone is a section of isolated and non-energised O/H which causes the safety systems to operate in response to the 'No-volt' condition. Likewise the Dynamic Power Changeover ...I presume that this will be an approved section where the transition between O/H power collection and on board power generation can take place.

The Pan Protection Zone is to do with the 755s themselves. It’s in an area that GPS detects the pan is raised but will shortly run out of wire. It drops the pantograph & applies the emergency brake so as no damage is done. Driver then starts Diesel engines & continues on his/her way with their tail between their legs.

 

[paulkidger]

The Pan Protection Zone is to do with the 755s themselves. It’s in an area that GPS detects the pan is raised but will shortly run out of wire. It drops the pantograph & applies the emergency brake so as no damage is done. Driver then starts Diesel engines & continues on his/her way with their tail between their legs.

Thanks. I am impressed that GPS can give sufficient accuracy of location to permit such a measure. As I mentioned, my first thoughts would be a dead section with the system operating on 'No-volts' Alternatively it could be possible to inject a signal into the isolated section of O/H to trigger events. On a different tack, I am impressed that the relatively small Power Units pack a mighty 2500 HP. Does anyone know of the operating practice regarding shutting down diesel generators on less demanding sections of the route.

 

[Fincra5]

Surprised its not done on a EuroBalise.

 

[VP185]

Surprised its not done on a EuroBalise.

We have Balises on GWR with the Hitachi fleet. The changeover is still done manually whilst on the move, the automatic power changeover function apparently caused too much interference with the signalling system

 

[Shwam3]

Surprised its not done on a EuroBalise.

745s & 755s have no balise reading capability.

 

[TheEdge]

Thanks. I am impressed that GPS can give sufficient accuracy of location to permit such a measure. As I mentioned, my first thoughts would be a dead section with the system operating on 'No-volts' Alternatively it could be possible to inject a signal into the isolated section of O/H to trigger events. On a different tack, I am impressed that the relatively small Power Units pack a mighty 2500 HP. Does anyone know of the operating practice regarding shutting down diesel generators on less demanding sections of the route.

You couldn't use a dead section system as you'd have them stopping every time they passed through a neutral section. They don't do any sort of engine shut down.

 

[Fincra5]

745s & 755s have no balise reading capability.

Ah right.

 

[Llama]

You couldn't use a dead section system as you'd have them stopping every time they passed through a neutral section. They don't do any sort of engine shut down.

You'd also have to have a track mounted APC inductor to open the VCB on the traction unit before the dead section unless you want to draw a large arc which would probably quickly find something earthed to short itself out on - and that would probably trip the whole power supply to the OHLE

 

[paulkidger]

You couldn't use a dead section system as you'd have them stopping every time they passed through a neutral section. They don't do any sort of engine shut down.

A time delay would overcome this. I presume that neutral sections are quite short but in the case of a non electrified branch, the 'dead section could be long...taking maybe 10 or even 20 seconds to cross. So a simple bit of logic...'If volts = 0 AND Time > 10secs, then initiate pan down and brakes on'..

You couldn't use a dead section system as you'd have them stopping every time they passed through a neutral section. They don't do any sort of engine shut down.

Re the engine shut down. I am basing this on comments I seem to recall, made when these units were introduced. Of the 4 engine generators, in the interests of fuel economy, some could be shut down when conditions permitted.

 

[TheEdge]

A time delay would overcome this. I presume that neutral sections are quite short but in the case of a non electrified branch, the 'dead section could be long...taking maybe 10 or even 20 seconds to cross. So a simple bit of logic...'If volts = 0 AND Time > 10secs, then initiate pan down and brakes on'..

It rather a complex solution to a problem that the GPS system has proved to work on. And it also involves putting up dead OHL where currently nothing is needed.

Re the engine shut down. I am basing this on comments I seem to recall, made when these units were introduced. Of the 4 engine generators, in the interests of fuel economy, some could be shut down when conditions permitted.

I've been driving them since they first arrived here and I'm yet to see them do anything like this. There was rumour they could do it but I've never seen it.

 

[dk1]

Re the engine shut down. I am basing this on comments I seem to recall, made when these units were introduced. Of the 4 engine generators, in the interests of fuel economy, some could be shut down when conditions permitted.

They are quite clever pieces of kit & control all power from the engines to whatever we’ve set the speed selector. Obviously wouldn’t want any engines shutting down on the 755/3s but we are running several 755/4s around on 3 engines. Nice to have all that power available for rapid acceleration & to recover any delay.

 

[paulkidger]

They are quite clever pieces of kit & control all power from the engines to whatever we’ve set the speed selector. Obviously wouldn’t want any engines shutting down on the 755/3s but we are running several 755/4s around on 3 engines. Nice to have all that power available for rapid acceleration & to recover any delay.

From a diesel engine efficiency and longevity point of view, it is probably better to have 2 engines on 50% load than 1 of full and the other subject to frequent starts.
I was looking at the Stadler data and noticed that there is twice as much power in the 744/4 and the 755/3. On this basis there is about 950kW for the 3 coaches of the 755/3. With the 755/4 there is an extra 950 kW, just for the additional coach. I notice that this is reflected in the acceleration with the 755/3 making 0.7 m/s2 and the 755/4 making 0.9m/s2. However on elec, the units have the same power (2600 kW) which results in a lower acceleration of the 755/4 due to the additional weight.(1.3 m/s2 vs 1.1 m/s2). I believe that the 'industry standard is 1.0 m/s2.

 

[MotCO]

From a diesel engine efficiency and longevity point of view, it is probably better to have 2 engines on 50% load than 1 of full and the other subject to frequent starts.

Presumably the engines would have to be on tick over, rather than competely shut down, so as you say, might as well use them at 50% power.