Vivarail chosen for fast charging trial on the Greenford branch

[whole diary]

[Electric train]

I doubt that charging from empty in three minutes would be possible.
I presume that they mean replacing the amount of charge used in the previous journey, which is still impressive.

Based on tests I have been involved in at IPH Berlin ( https://www.cesi.it/about-us/overview/iph-gmbh/ ) testing third rail shoe contact current capacity when static.   Once you get over about 4kA (4000A) at 750V DC^▸ (Direct Current) arcing and burning starts which is not a problem for a train if it starts to move as the contact surfaces scrub.  To get over the 4kA DC limit the downward pressure of the shoe gear needs to be increased but you get to the point of the mechanical limit of the force required.

Of course the transfer may be AC not sure the ORR^» (Office of Rail and Road formerly Office of Rail Regulation - about) would be keen on an RMS Voltage above 750V AC.  Another option could be high frequency AC but then there are RFI issues and the risk of shock from exposed conductors.

It will be interesting to see what the charging system will be.

[broadgage]

For fast charging, perhaps a short length of 25 KV overhead might be simpler.
Out of reach, so can be left live all the time.
Much lower current due to the higher voltage.
Can be of a cheap and simple design as not intended to be used at significant speed.
Multiple pantographs are possible, in order to pick up enough current.

Another advantage is that if needs change, the trains can re deployed to other routes that are partly electrified.

[IndustryInsider]

Won’t they be using their modified D78 stock?  In other words no pantograph fitted, but fitted with DC^▸ (Direct Current) shoe gear?

[ChrisB]

I understand thst is so

[stuving]

I understand thst is so

Of course it is - as announced by Vivarail! The relevant story on their Fast Charge system is hard to find, for want of links, and some the other details are elsewhere. But it does include:

With assistance from the UK^▸ (United Kingdom)’s Department for Transport and Network Rail, Fast Charge’s trial is due to start in early 2022 on the West Ealing-Greenford line in London, after that it will be fully approved for use on the network for all types of battery train.

According to Vivarail, the Fast Charge application is quite simple. Lengths of conductor rail sit between the running rails. Beside the track is a container full of batteries (the company aims to use second-hand batteries in power storage banks, possibly from the automotive industry). All the train has to do is pull to a stop in its normal place. At that point, and without any need for the driver to do anything, a high current shoegear connects to the conductor rail.

So they are trying to prove this Fast Charge approach and the hardware. They reckon the buffer battery at trackside is worthwhile to avoid a high-power mains feed. The fast transfer of energy from it to the onboard batteries is well above what a small train like this would normally need, by AC or DC^▸ (Direct Current). But clearly adding AC would cost a lot at any power level, while at DC the current goes straight into the batteries. The electronics to control it and match voltages can be offboard, apart from the cells' charge controllers that are built into the batteries.

They talk about current levels of 1 kA or a low multiple of that, and that agrees with what ET said above. They also mention ceramic shoes to cope with the heat, and I don't suppose they will use standard conductor rails either for the same reason.

So it's all been planned out and, apparently, ready to go ... soon. Of course getting it all up and running on schedule is the hard bit, and the suppliers of both new and rebuilt trains have now got a truly lousy reputation for that.

[stuving]

There's now a youtube video of a presentation by Vivarail on Fast Charge, recorded at a PWI* on-line. It concentrates on the safety case, perhaps because of the audience, which leads to the impression it will have a lot of failures due to false alarms. But I can see that for their programme to do the Greenford trial, getting ORR^» (Office of Rail and Road formerly Office of Rail Regulation - about) and NR^» (Network Rail - home page) approvals was probably the biggest activity and highest identified risk.

The numbers are not quite the ones I got from their previous presentations: now 300 kWh of batteries per DM (and 1 MWh per Trackside Charge Unit). The transfer is of 1 kA at 800 V, and is expected to replace 30-50 kWh per train used in a 5-mile round trip in three minutes. So the control system design has dictated by the need to charge automatically for as long as possible during the turn-round, and without the driver stopping to do anything special.

One those numbers there is easily enough capacity to cope, but then there's no mention of "losses" or "efficiency". You just can't shovel all those kWh around at that rate without a lot of them escaping!

*Permanent Way Institution

[IndustryInsider]

So the control system design has dictated by the need to charge automatically for as long as possible during the turn-round, and without the driver stopping to do anything special.

That's a relief.  I wouldn't want to be the driver who had his train cancelled because he forgot to plug it in the the charger...a headline makers dream!

[Electric train]

They talk about current levels of 1 kA or a low multiple of that, and that agrees with what ET said above. They also mention ceramic shoes to cope with the heat, and I don't suppose they will use standard conductor rails either for the same reason.

The use of carbon ceramic make sense especially as it is static current collection also the shoe look larger than normal travelling shoes.  The key as always with electrical connections the greater the current the larger the surface area required the surface area can be reduced by contact pressure, there is a limit of when you start to lift the train 

So it's all been planned out and, apparently, ready to go ... soon. Of course getting it all up and running on schedule is the hard bit, and the suppliers of both new and rebuilt trains have now got a truly lousy reputation for that.

This has been in discussion with RSSB^▸ (Rail Safety and Standards Board), ORR^» (Office of Rail and Road formerly Office of Rail Regulation - about) and NR^» (Network Rail - home page) for at least 5 years

[grahame]

Any news on when the trial start?  Trains in public service?

[stuving]

Any news on when the trial start?  Trains in public service?

"Later this year", according to Vivarail. Were you expecting anything more specific?

[stuving]

Eversholt have announced that they are getting Vivarail to add some batteries to their "Renatus" modernised Class 321 EMUs^▸ (Electric Multiple Unit). From their news page:

Eversholt Rail and Vivarail to develop Class 321 BEMU

Eversholt Rail and Vivarail have signed an agreement aimed at developing battery power – and range extension – to the Class 321 ‘Renatus’ fleet.

The 30 unit ‘Renatus’ fleet is a product of £65m investment in AC traction, air conditioning and upgraded interior.  Completed in 2019, it provides a high-quality passenger experience, proven reliability in intensive operations and is widely compatible on the UK^▸ (United Kingdom) network. This fleet is currently operating on the Greater Anglia network until the introduction of their new trains is completed.

Eversholt Rail and Vivarail are committed to supporting the UK Government’s ambition to decarbonise its rail sector by 2050, and the Scottish Government’s objective of doing so by 2035. This proven and reliable fleet is an excellent fit in terms of characteristics, fleet size and availability for conversion to a Battery Electric Multiple Unit (BEMU). Vivarail, as the designers and manufacturers of the UK’s only battery and hybrid trains currently in passenger service are well positioned to progress this development.

We will be working together to develop a design to integrate battery technology to provide between 20 to 30 miles of self-propulsion. Enabling the fleet to operate on non-electrified or partly electrified routes would offer the opportunity to increase the range of modern, low-carbon options to accommodate passenger demand; to enable fleet cascades; to improve the passenger experience; and to bring air quality and decarbonisation benefits to local areas.

Through discussion with train operators, regional sponsors and DfT^» (Department for Transport - about) a number of opportunities have been identified across the network. The technical and safety case development will continue throughout 2022 and in parallel Eversholt Rail and Vivarail will be engaging with the market to assess the viability of potential routes. This will inform the decision on further investment in the fleet.

Since this is the same traction package as on the 455s, it must use 750V as its intermediate DC^▸ (Direct Current) voltage. So the batteries and linking electronics can be the same as on the 230s, or a bit beefed up.

What applications do they have their eye on? Much the same as for the ones based on the D78s, I guess, but offering a real train?

[stuving]

Since this is the same traction package as on the 455s, it must use 750V as its intermediate DC^▸ (Direct Current) voltage. So the batteries and linking electronics can be the same as on the 230s, or a bit beefed up.

What applications do they have their eye on? Much the same as for the ones based on the D78s, I guess, but offering a real train?

One thing that's implied, but not mentioned at all in that publicity, is that presumably this involves charging from on-board traction power. That would be a new bit of Vivarail's kit of parts, but one you could have guessed they'd be working on. It leaves open the question of whether shore power or a charger would be needed at the far end of the line.

[bobm]

Don’t know if it’s connected but the Greenford Branch is closed over the August Bank Holiday weekend and the first two Saturdays in September.  (There are no Sunday services anyway).