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EDN Europe's Editor Graham Prophet posts a selection of comments and insights prompted by the many items of industry news and rumour that cross the editorial desk or are gathered on his frequent travels to interviews, press conferences and events around Europe - and further afield - and somehow never find their way to the magazine or the web site, recovering some of the information otherwise lost in the noise level...

Monday, January 04, 2010

Snow job

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For many of us, this (Monday 4th January) is the first day back at our desks after the mid-winter holiday, so please let me wish you a happy New Year, and good fortune for 2010.
What have we learned since we last convened here? For one thing, that Eurostar power cars (which apparently are little different from TGV traction units) don’t perform well in the face of very-low-temperature powder snow.
Here’s what intrigues me; and before writing any more, I should make it clear that the following may simply expose my ignorance of HV traction systems design.
I can understand that in winter the train engineers fit baffles to stop snow penetrating via cooling ducts into the inner workings of the electric drive. I can understand that very fine, very cold snow might defeat that precaution. I can understand that with a sudden temperature rise (entering the Channel Tunnel, for example) that snow might melt rather rapidly.
I don’t understand why that’s a problem. I would expect all the control circuitry to be sealed to at least IP66 or 67 standards. And I’d expect all the HV busbars and power cabling that feed the motors to be insulated – clearly there’s a lot I don’t know about this kind of design.
So, when the Eurostar trains ground to an embarrassing halt, exactly what shorted to what? And even allowing that it got very wet, very quickly, why was it able to do so? There may be useful lessons for designers of other systems in the answer. Nothing I’ve been able to find tells me this to any useful level of engineering detail, so I’m going to ask the Eurostar press office if they have a diagram they can share with us. Meanwhile, if anyone out there knows the definitive answer, please let us all know.

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