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Sir Alastair Morton won't accept that Railtrack's EMU acceptance process is uniquely difficult – those at the sharp end disagree
There is a popular view that the delays to vehicle acceptance are down to Railtrack's pettifogging paperwork rather than real world risk of potentially dangerous interaction between an electric multiple unit's traction equipment and the infrastructure. But, as this column has pointed out ad nauseam, the train makers are addressing real issues rather than trying to prove precisely how many angels can safely dance on the head of an insulated gate bipolar transistor.
Take for example, the issue of electrical resonance in the contact wire which, thankfully, I suggested in the April Informed Sources might prevent the Alstom Class 334 for ScotRail getting its expected Interim (I) passenger safety case.
Earlier, informed brains on sticks had been suggesting that the Class 334 safety case had run up against resonance issues. Checking with Alstom's Juniper BoS confirned that there were three issues, two of which were sorted and one looked likely to be resolved with further work. Hence the caveat in an otherwise up-beat report.
And it turned out that I had been right to be cautious because the next time I checked with Alstom it turned out that the resonance problem had, after all, stopped the I(Passenger) submission going to the SRP. A fix is now in the pipeline, but there is a chance that tweaking the software may not be enough and an electrical filter might yet have to be fitted.
Understandably, three phase drive traction package manufacturers focused on electromagnetic compatibility with signalling and telecommunications equipment. Here, problems are caused by the traction currents returning to earth via the rails. But, and please pay attention because here comes the techie bit, ac three phase drive trains have another potential problem.
Right, I'll keep it as simple as I can. In a three phase drive train a grey box called an inverter takes in direct current and turns it into variable frequency alternating current which is fed to the traction motors.
So, on a DC electrified system, like that south of the Thames you can feed the raw 750V DC into the inverters. But under the 25kV AC overhead line you have to make your own DC to supply the inverters. No problem, because inverters are clever grey boxes which can work both ways.
In an AC train, the 25kV comes down through the pantograph to a transformer which drops the voltage to a more usable level. This AC supply goes into an inverter running ‘backwards' and out comes DC which goes into the inverters which feed the traction motors.
Now the ‘backwards' inverter, usually called a four quadrant (4Q) converter, runs at a constant frequency. Which is where resonance comes in, or not, because the frequency of the 4Q converter can get back to the contact wire.
As a rule of thumb, resonance is only a problem if the frequency at the wire sees at the pantograph is over 3,000Hz. Thus, on a Class 323 which has two traction packages fed by a single pantograph, the sums look like this.
Each 4Q controller has two circuits. Each circuit switches at 450Hz, giving 900Hz combined. Two traction packages double this up to 1,800Hz – contact wire happy. This, of course, by design not coincidence.
But the trend in the latest electric multiple units is to have several modular traction packages fed from the transformer, each one feeding a bogie. So, you can see that, depending on switching frequencies, resonance could be more difficult to prevent.
Resonance is essentially an oscillation set up in the circuit represented by the traction power supply circuit. And the resulting high frequency variations in the voltage could do nasty things to other electrical hardware, such as lineside transformers or bits of other trains – particularly older trains with ageing insulation.
Now, obviously, you can do clever things with software that controls the 4Q converter, but there are limits and if tweaking operating frequencies is not enough you may have to add components to your power circuit, called filters, which filter out the nasty frequencies. Which is where Alstom are.
Meanwhile, remember how we all laughed when the Class 323 shut itself down when there was ice on the contact wire? This was because the safety software saw potentially hazardous frequencies in the ‘white noise' generated by the arcing when the pantograph ran over the ice and acted accordingly. The solution was to add a software patch that could differentiate between arcing (normal) and the drive malfunctioning.
So, it was interesting to note that the original Interim acceptance for the LTS Class 357 did not allow the train to run at temperatures of 4degC or below.
All of which make the point that there are real issues to be overcome in introducing new electric traction and that operators have to demonstrate to the System Review Panel that such issues have been overcome. And, of course, this is having to be done on a railway with a near unique safety case approach.
Well, that's my view. But Shadow Strategic Rail Authority Sir Alastair Morton disagrees.
On 3 May there was a meeting of the SSRA Rolling Stock action team which, you will recall, was set up after John Prescott saw lots of trains at Derby sitting around waiting for a safety case.
After the meeting, the SSRA put out a press release. Mike Grant, SSRA Chief Executive was quoted as telling the meeting that the present situation is unacceptable. But, he added, modestly, ‘Following the SSRA's intervention at the request of the Deputy Prime Minister John Prescott more of the new vehicles are cleared to enter service'.
He added ‘with the prospect of more orders on the way the industry has to get its act together and should be thinking strategically to avoid the mistakes of the past'.
Well, such strategic thinking is over my simple commercial head where you make products that work and people buy them. And, being an old grouch, I think that progress with acceptance has everything to do with my engineering chums burning the midnight oil and very little to do with steering groups.
But, of course, with the 25 May summit coming up there was a premium on pre-emptive posturing. Thus Railtrack said that the Class 357's Interim (non-passenger) acceptance certificate could be converted to an I (Passenger) if nine criteria were met. They were, the Class 357 ran in passenger service, for one day, and then went back to testing – provided there wasn't a frosty spell.
Alstom and National Express contributed to this outbreak of spontaneous posturing. On April 19 Alstom announced that the I (Passenger) safety case submission for the Gatwick Express Class 460 Juniper EMU had been ‘endorsed' by Railtrack's ‘rolling stock approval body'. ‘On the confirmation of some minor issues, the Class 460 will be certified for passenger operation by the end of April' the company added.
In other words they were saying that the SRP, its BoS, the ISA and sundry other TLAs were generally happy. In fact, the ‘I' Passenger was due to awarded at the 9 May SRP hearing – and wasn't.
Why not? Well Alstom still had to clear a couple of minor details, concerning doors and axle certification while Gatwick Express has a couple of maintenance and operational issues to resolve.
But, shoulder to shoulder with Alstom, Gatwick Express, Project Manager New Trains Tony Francis said that the endorsement meant that the franchise was ‘in the final phase of the testing process before the fleet is put into full service'. He added that the Class has now accumulated over 20,000miles demonstrating ‘a high degree of reliability'.
In fact, National Express management is critical of both its train builders' performance at a high level. But if it means giving the DPM some easy kudos, a tornado of spin was in everyone's interest during May.
So far, so cynical. But at the end of the release, Sir Alastair Morton had his three pennorth. And he said, apropos acceptance.
‘What happened up to last year was simply not acceptable. On the one hand some of the worlds greatest engineering groups did not plan and manage the production and commissioning of rolling stock that worked from day one. On the other hand Railtrack did not fulfil its leadership role in identifying and overcoming acceptance problems. I have discussed this with Sir Philip Beck and welcome his assurance that this will not be the case in future. Indeed this is already becoming evident'.
Well, up to the end of 1998 not a lot had happened and everyone knew that the process needed refining and Railtrack had taken this on board. And once the first EMUs were ready to start running at the start of 1999 testing was under way. The Class 458 would not have got an I Passenger Certificate in February 2000 if 1999 had not been a successful year. And, as remarked before, we should not overlook the various route specific safety cases for existing kit such as the Class 92 and Networkers being extended at the same time.
Then Sir Alastair switched to hectoring mode. ‘As for the suppliers, foreign owned but employing thousands in this country, they will either get it right from now on or their competitors will elbow them out of this major market, now one of the most promising in the world for them'.
This did not go down well with those present at the meeting. Several told me that it did not reflect the mood of the meeting. Knowing that I would have my ear bashed Sir Alastair ask me to give him a call and a total non-meeting of minds ensued.
My view is that, other than some self inflicted wounds rehearsed comprehensively in this column, the big problem with acceptance has been that we have been putting new trains, but powered by established world class traction packages, through a uniquely difficult and completely novel and evolving acceptance process on a pretty peculiar infrastructure.
Sir Alastair disagrees. In his view I am reflecting the views of an industry with the typical cry of ‘We're British, it's very difficult, we're doing our best and we'll cry if you are nasty to us'.
As for Railtrack, the SSRA Chairman still says they should help the manufacturers resolve their problems. But how? Railtrack can't tell the big three how to write software to modulate inverter frequencies, all it can say is that there is a potentially dangerous output from your traction package under this credible fault condition please do something about it'.
That is the way the safety case process, designed to maintain safety in a fragmented railway, works. Where Railtrack can help is through the Yellow Book which gives one, proven, process for handling engineering change and in its third version was overseen by a pan industry steering group. But it doesn't have any circuit diagrams of inverters guaranteed not to annoy antique reed track circuits.
Nor am I convinced by this ‘elbowing out' threat, which is so corporate old railway. BR Chairmen used to make the same threats.
Empty threats then as now. I mean, suppose the SSRA had a potential supplier today offering a working train with I (Passenger) acceptance, already building up reliability. Sir Alastair's promotion of a market red in tooth and elbow might suggest said firm had a competitive edge and would be smiled upon.
Fat chance. As reported in this column, the SSRA seems to think that the best thing you can do with your safety case is help your competitors get their safety cases so they can elbow you out of the market. Give me strength.