5 Eurostar trains fail due to condesation in the electrics

Electrical power control "boxes" both internal and external, on such a device as a passenger train (or freight), should be sealed from the environment ALL of them. Gas and moisture tight, much less snow tight.

I meant places where a machine failure would cause panic and stuff. Just like an engine failure on a taxiing aircraft isn't a big deal but somewhere over the ocean it is. Been there, big 767 over the Atlantic, left engine went PHUT ...

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lurch wrote in news: snipped-for-privacy@4ax.com:

No argument there, as long as cooling requirements are met. Sometimes these lessons are learned the hard way.

--Damon

The problem is the lessons aren't learnt.

Since the failures occurred deep inside the tunnel, it simply appears that the trains had been in the cold dry environment, possibly even powered down and the hardware temperature dropped lower than normally.

Entering the warm and humid atmospheres of the tunnel, the hardware temperature was apparently below the dew point temperature of the air in the tunnel and water starts to condensate on any cold surfaces. This same happens when you spend some time in the cold and then enter a warm humid room and your glasses become opaque due to the condensation. Driving in extreme cold into a warm and humid road tunnel can cause dangerous situation, when there is a strong condensation on the windscreen or even freezing.

Imagine what happens when condensation occurs on current PCBs with very small track to track distances. One way to avoid such problems is tropicalization e.g. by coating assembled and tested PCBs. Coating is often required in addition to the tropical climate also in polluted industrial sites and on ships, since the salty dust gets everywhere.

I have no idea if Eurostar trains use tropicalized systems or not, but the failure mode seems to indicate that this has something to do with condensation and not just cold/hot/cold cycling.

Problems like frozen pneumatic breaks are common when going from a relatively warm and humid environment to a very cold environment, which would cause condensation and ultimately freezing in the pneumatic lines, but this would occur only after an hour or two after _exiting_ the tunnel containing humid and warm air.

NOT inside ANY enclosure that was sealed with zero moisture inside, it doesn't.

Ever heard of NEMA?

It sounds to me like a good idea to have tested one of those locomotives there, or someplace that gets blizzards.

It appears to me that blizzards do occur, even if only once every

30 blue moons or whatever, in the USA as far south as Dallas and Memphis, and accumulating blowing dry snow short of a blizzard can occur as far south as Houston and Birmingham. I would hope that any transit vehicles made specifically for specific locations or areas can take whatever weather such locations get, including the weather they get rarely.

- Don Klipstein ( snipped-for-privacy@misty.com)

-- Boris