From MSNBC, 12/19/09:


Story is here.

Whew! What a mess. Here's another story from the BBC.
BBC 12-19-09

You'd think that at least they could explain why five trains could all break down at about the same time! Why should a switch from very cold to very warm temperatures make such a difference?

It makes no sense at all, Lou. The temp in the tunnels presumably is stable all year long, due to being so far underground with the thermal mass around it steady-state due to all the water above. That is not rock that is going to shift in temp much. You are probably looking at 45-degrees inside the tunnel. If the claim is that the problem is at the junction of the rail at the tunnel mouth(s), then presumably you can bring in a diesel and just tow the trainset out of there and to an unloading point. I think there is more going on here than management is letting on.

Even if the disabled train were 2500 feet into the tunnel and you were worried about diesel exhaust, I should think they could have brought in a diesel power set with a string of flatcars and hook up the stalled train to the last flatcar, and just started pulling!

They're saying that the extreme cold outside interacted with the much warmer air inside, causing condensation that then shorted out the electrical equipment. When the power went out, the 5 trains inside the tunnel at the time all stopped moving.

I'm not 100% sure that what they're saying make sense, perhaps Bill can chime in on that idea. I do understand the idea of condensation, I guess I'm just surprised that there was no protection for that, even though I'm not sure just how one would protect against that.

As for why it took so long to rescue the trains, I do think that someone dropped the ball there.

How many years/winters have they been runing these trains and they are only having this trouble now?
These trains have been around for almost 14 years/ winters???
Something is not right here? This trouble should have happened in the in the previous winters as they have been just as bad!

From Minneapolis, MN Star-Tribune, 12/20/09:


This story is here.

BBC, 12/20/09:


And they are offering compensation to those who had been trapped in the tunnels:

Read this story here.

The claim of "condensation" on the electrical gear "inside" the tunnel is a bit peculiar. Here's why: the outside air is very cold. Cold air has no ability to retain moisture; that is why the relative humidity of cold air is very low. If the cold air moves into the warmer tunnel, it is not bringing in any moisture with it. Now you could argue that the cold air is meshing with the warmer (relatively) air of the tunnel and then the humidity trapped inside that air is now being condensed, as the temps fall, but this is a bit peculiar. The tunnel air is itself rather low; perhaps 45 degrees or so, due to it being inside the cold earth mass underneath the cold water of the Channel. So it is not maintaining a lot of humidity in the first place, to condense out.

Look at the situation in the Summer. The outside air is quite warm, and humid, and has a high relative humidity. this warm air interacts with the cooler air inside the tunnel and the moisture condenses out. You are sure going to get a lot more moisture in that scenario that you will with cold air!

Perhaps a more logical explanation is that insulation is breaking down with age. So then that is a result of lousy specs and poor purchasing controls. Any comments out there?

AP via WTOP radio, 12/21:

Complete article.

If my memory doesn't play me false, GG1 electric locomotives on the Pennsylvania Railroad many years ago had this same rare problem, an unusually powdery snow getting through the air filters and melting inside the traction motors. I would have thought that today's motors would be induction motors (no commutator) and would be less susceptible to a little bit of moisture.

Lyle, your analysis is correct. Melting snow would create a water "short" across the commutators at the brushes of old DC motors with commutators. Where the new motors have no commutators, the melting of snow powder should not penetrate the insulation - unless the insulation in the windings, now 14 years old, had deteriorated by age. If that is the case, then there are incipient problems in the selection of components. The motors were wound with wire with insufficient insulation to withstand the recurrent and cycling heat load created by the current on rapid acceleration, when repeated over years. Anyway, that is my analysis. Anybody have direct experience with this?

Here's another thought. If the traction motors were oil-cooled (and the oil going to a remote radiator for heat exchange) then the entire motor would be immersed in an oil bath and NO moisture would get into it, and no problems. they use these oil-cooled generators on big inter-city and transit buses (300 amps at 24 volts), where the crankcase engine oil is routed through the generator to cool it. Works like a charm.

AFAIK I don't believe the traction motors in any of the high speed trains derived from the basic TGV design are oil cooled. They are forced air cooled.

The two possible explanations are:

(i) dry fine snow got into places where they should not, and then melted inside the tunnel causing electrical problems.

(ii) condensation took place on very cold surface in areas where such should not occur, again causing electrical short.

It is not clear at all the the problems were only in the motors because that would only cause the motor drive circuitry to go off line, and would not cause the train to lose hotel power. The problem was apparently more pervasive affecting the entire power supply control system of the train. If the reports of loss of power in the catenary due to short is true then the problem would appear to be in the HV side of things, perhaps a short in the main HV transformer or some such. Bur still not clear why the main CB would not prevent a catenary short.

jisd is quite correct, the traction motors are universally air-cooled designs, mostly because they are lighter weight and because you get away from the messy problem of hoses and connectors and heat exchangers. I was just making the (academic) observation that IF they were oil-cooled you would not get these problems.

Whatever was going on in there, condensation would be most unlikely. That is simply because cold air has so little moisture that there is not enough to condense. The idea of fine snow getting in where it does not belong intuitively has more merit.

Yet, as jis trenchantly observes, the loss of hotel power remains most puzzling. It is hard to fathom that the HV side is fritzed, as the central breakers are specifically designed to protect that system. And the HV engineers have both a lot of practice and a lot of experience in this. Look at all the HV catenary stuff in places like Austria and Switzerland and Russia, where severe wx is a constant factor.

Just musing here, but if the motor power controllers went blonk, and there was some subtle inter-dependence that was not thought of at installation, then that could knock out the hotel power as the main power intake lines would drop out. Sure is a puzzler, especially the lack of reset capability. It will be interesting to see what excuses management dreams up for public consumption. (I'm personally betting on poor quality control in components selection and manufacture).

Note the implications for future electric pax rail lines with tunnels through the Rockies.

Dutch, the only condensation scenario that is plausible is the following:

Train running through very cold air gets certain parts of the electrical system that normally does not radiate much heat cooled down to very low temp. These would conceivably be non-power carrying but still critical control circuitry.

Then train enters hot humid air which comes in touch with this cold surface and condensation forms which somehow leaks into the electricals of the control circuitry fritzing them out.

This is consistent with the trains running fine while out in cold and then failing soon after entering the warm humid tunnels. This would also be consistent with failure of not only the motors and controls, but even HVAC. It still does not explain why there should be failure of the HV CB, if that were the case.

Now here is the conundrum, unexplained, with the jis analysis: there should be no hot, humid air for the cold parts to come into contact with to attract the moisture condensation. Reason: the inside of the tunnels are probably about a steady 45 degrees. There is little moisture trapped in air at that temperature. Outside the tunnel, that part of Europe does not get very cold; perhaps down to 15 degrees. So you are looking at a 30-degree temp differential.

Now look at what happens on a hot (and humid) Summer day. The tunnel is still at about 45 degrees. The steel gets cold. The train emerges into very humid summer air (the heated air contains a huge amount of moisture), perhaps at 95 degrees. You have a temp difference of 50 degrees - a lot more than in Winter, and a lot more humidity. Yet nothing happens. -- there is more going on here than Eurostar management is telling the public about. Hey, it is just speculation; I'm sitting here in my comfy armchair, not poking around in that tunnel! [The blowing snow getting into parts with weakened insulation looks plausible, but still does not explain the "hotel power" loss problem.] If there is a systemic problem, then the public is not going to be buying any more tickets, and Eurostar finances as so shaky that that is the one thing that management cannot have.

Good point Dutch. Apparently both the lowest temp and the change in temp played a role AFAICT. I wonder if they have observed a similar phenomenon in the absence of snow. That would be a critical differentiating factor between the two possible causes.

Whichever it is, it seems to me that the fact that the train suffered complete power failure suggest that the power control system somehow got fritzed and not individual power consumption points like the motors. Again, just an armchair guess from this end here.

Jis points out accurately that the power control system fried, not just power use points such as the traction motors or traction-motor controls. What this suggests, given the apparent inability to re-route power through a back-up or secondary control circuit, is a failure of the designers to appreciate a subtle compound failure.

You see this in the aftermath of spectacular air crashes. In the case of TWA 800 which went down after take-off from JFK NY (older Boeing 747), it was determined that the designers had placed the air-conditioning compressor packs right on top of the in-frame center fuel tank; the hot-running compressors then heated the remaining fuel (and vapors) in the tank, and deteriorated insulation to the in-tank pumps then set the stage for explosive ignition. A classic example of what "looked good" in the design stage not working out after a few decades of service.

Simple systems tend to be more reliable systems. The inability to manually "key over" the elaborate control and get the train out of the tunnel, even at a crawl speed, led to this stranding fiasco. Yet a fixed by-pass key system, that would place a limited amount of power onto the traction motors (only on-off, no speed increment) would have been handy. It will be interesting to see what the technical Report states, assuming it is candid.

From UK Press Association, 2/12/10:


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