An amazing amount of detail on building electric locomotives for hauling heavy rail over a mountain pass and through a tunnel - including discussion of 200F cab temperatures in big locomotives being a reason for considering the alternatives. It goes through design and implementation of the whole system, and is a wonderfully technical, yet still reasonably written, description of a comprehensive solution to the problem of hauling heavy freight over a mountain.
Nice! Will be going through it.
I’m rather surprised at the depth and quality of the comment “thread” that follows this piece. How did they assemble these, was this piece sent out earlier for “comment”? It seems some of them are replying to each other, yet they all seem like they’ve had the time to think about it and do basic research, back-of-the-envelope calculations, and coherent thought ordering in order to put it into a written form, so I don’t think it’s a transcription of a commentariat.
I also find the fact that there are definitely the proponents of various specific strategies, yet they (sometimes grudgingly, sometimes not) acknowledge that in this case, at the very least, it was a perfectly appropriate technological choice.
It’s also interesting to me that the frequency is very low - 25 cycles (and Europe today often uses 16.7 cycles for their train AC) … this is well before the 60Hz line “noise” issue was even a problem for audio or other uses, so I’m very interested if anybody has any details on why those low frequencies are considered advantageous - are there lower transformer losses? Is it simply easier to generate with less expensive alternators when the rotational frequencies can be much lower? Is it something about induction (or synchronous) AC motor efficiency? I don’t get it.
Of course, there is a lot of talk about the issues between various AC strategies - today we don’t have that tradeoff since VFDs are basically ubiquitous, but I have a feeling that these are worth keeping in mind for simpler implementations and/or for reducing our dependency on VFD tech when/if semiconductors are more challenging to get our hands on.
Either way we look at it, coal is basically gone, wood is no longer a viable global energy source at scale, and what electricity we can generate is going to become more and more costly - dams require great effort to construct and operate and maintain, power lines are expensive to keep up and safe (ask PG&E how that’s going), and the idea of local production for local use is again going to become more important. The whole “the grid averages it all out” sort of thing is not going to always be the case.
My assumption is that this was compiled out of some journal article and subsequent responses, but I’m not really sure. Back in the “mail letters to the publication” age (which wouldn’t be a bad thing to get back to, all options considered).
My AC waveform knowledge is pretty weak. I didn’t dive down the hard EE road in college, where that sort of stuff would have been considered. I do know that aircraft tend to use higher frequency AC (400Hz?) because it allows the alternators and equipment to be smaller. They talk extensively about the overload performance of the system, and how it can sustain beyond continuous rated power for long periods of time, which implies an awful lot of thermal mass. Perhaps related?
There’s also the skin depth effects - 60Hz AC is less than 1cm useful depth, so lower frequencies would use more of a large conductor. I’m not sure if this was well understood in the early 1900s, or if it was a consideration.
However, I think your “power is going to be more costly” statement is missing a few things. The concept of power that we’ve used for the past 50-80 years - “As much as I want, whenever I want, for some low cost per kWh year round” - will likely get more costly, but power, for large periods of time, will be quite cheap.
This is where the whole “Well, we’ve just gotta have batteries so we can use power at 2AM on a dark winter night!” concept starts to break apart on the rocks of reality. Dealing with the realities of off-grid power, most of my power is “too cheap to meter” - on a sunny day, the cost of an extra kWh of power is literally zero if I’m running below current production. And then, in the winter, my power is painfully expensive - I figure my generator is around $0.75/kWh or a hair higher depending on fuel prices. I conserve power aggressively during those times, and am likely to be using the kerosene lantern for combined heat/light (which… eh, the fuel I use for that isn’t cheap either, but it does burn cleaner than straight kerosene).
This is likely the future of the power grid - radically variable power costs. And I don’t have an objection to it, but there’s going to be a lot of having to learn to think about power differently than we currently do.
Oh, granted. What I’m referring to specifically is industrial-scale power - electricity for trains and heavy industrial construction, etc. I expect that to either just not be reliable, or to be reliable but very expensive, or to become much more localized and reduced in capacity, depending on the resources and economics of every region. You’re totally right in the “small power” concept - solar, local hydro/wind, etc. But I don’t think at all that we’ll have reliable, cheap grid-scale power much longer - and thus the relevance of considering alternatives, such as lower power transport (rail is pretty efficient - you can’t run that off solar, but that’s by all standards a pretty modest hydro setup, so I’d expect some regional transport to still be doable at that scale, but, again, the regenerative aspects of it are less useful since storage becomes a big question. And of course, the dam has to be built and while back then they had lots of coal to run steam shovels, in a future with expensive petrol and not a lot of wood/coal or reliable grid, re-bootstrapping this sort of thing won’t be easy. Building dams by manpower alone is a daunting project. Have any of our seriously huge dams been built without significant aid of heavy machinery?
Given how critical electricity is to modern civilization, and how little works without it, I would be willing to bet on it for quite a while longer. If push comes to shove, the power grid will get resources to maintain it, even if it’s not maintained quite to the 4 9s level reliability we see today (depending on region). The lifespan of dams is quite long, and we’ve been doing hydro power for more than a century - it’s well proven and can be done on a more limited technical base.
I’d have to do the math, but I’m not sure I agree with you about not being able to run rail off solar. Most rail right of way has an awful lot of area one could put panels up on, though they’re quite distributed and subject to theft. A 5MW solar facility just isn’t that large. However, if we’re going to electrify freight (which I think is at least somewhat likely), it doesn’t make sense to put the power generation along the rail, given the power grid we have. Centralized solar farms are an awful lot more convenient to work with, and if you have something that ties into an existing set of locomotives, you could use electric power from near the rails when it’s available, use a battery bank for runs off that, and kick on the diesels for long distance, up to speed runs across the plains (where rail is insanely efficient).
If we see de-electrification, it will start with rural areas (that only got power in the 30s and 40s). I’d expect most of the grid to remain operational for an awfully long while, though - I certainly expect it for most of my remaining life, even if reliability suffers a bit.
Region depending, I think. Unless some tears down the columbia river dam system, the northwest will have a ‘traditional’ grid system for a while yet. Even a reduced flow version will be useful as intermittent generation to supplement wind and (desert side) solar.
Well this is the ebike club…
Not really. As long as you can maintain minimum flow for wildlife, you can crank hydro up or down to fill in during the ‘drain from storage’ periods.
Diesel electrics have been around for over a century. At the most, you’ll run cantenary lines to the prime movers. The nice thing is, however, most of the ‘good’ sites have already been built. Some of the more marginal ones have been torn down for wildlife purposes, but there’s a lot of infrastructure already there. And the sites that don’t have them… likely won’t ever be built at all.
I’d say harder to maintain or less customer/use per maintenance dollar lines will be replaced with solar/wind. Going offgrid, but since you’re still part of an economy that has electricity, more encouragement of those outliers in the rural areas to be offgrid solar. PUCs will say 'okay, ID power says maintaining that line will cost X, you only use the power that array Y can provide, and we’ll allow them to stop maintaining the line as long as they provide that array.
If the cost of gensets was lower than the cost of sending electrical lines to everyone, the idea of rural electrification would have gone a lot differently.
I found this whole thing to be very interesting.
On format: I think this is, yes, from a journal of discourses- there is an imprint on the second page reading “A paper presented at the 240th meeting of the American Institute of Electrical Engineers”. I’m not sure how the discussion making up the second half of the document was assembled- I wouldn’t be surprised if advance copies were provided to peers before its presentation and they prepared comments for inclusion in the journal, if those were collected after the presentation, or even if they were transcripts of comments given the day after the presentation or something.
I have a few technical observations. Three-phase power is recognized and employed today as the electric power medium of choice wherever large amounts are needed- from 1kW and up industrial motors to trans-continental transmission. Only in some edge cases do you get transmission via HVDC (undersea cables, for example) or something else. The discussion about 3ph versus single phase versus DC for traction applications is interesting- it really reflects the limitations of their time. No mention is given to the advantage in conductor sizing, except maybe a sideways reference to the 3ph motors being smaller than single phase motors by the single-phase advocate in the discussion, who promptly claims that the increased weight of a single phase motor is an advantage in traction. (He’s not all wrong, either).
The fixed-speed nature of that time’s 3-phase motors makes me curious what they knew about motor design. Obviously enough to pull this project off handily. I think the single phase AC motors used for traction must have been induction motors (hence the discussion of slip). Is there some reason that would have prevented the motor designers of the day from simply extrapolating the design of a single phase induction motor to three phases and still have gotten the same asynchronous feature they wanted? I think I also saw stated somewhere that they were using an even lower frequency than 25hz for their single phase equipment- 15hz maybe? Something ludicruously low, and I’m really not sure why. For synchronous motors, I understand why they might use low frequency to get low RPM even with the disadvantages.
On frequency- I’m no EE but my understanding of the topic is that higher frequencies allow you to use smaller transformers and gain higher efficiency. e.g. inverter welders available the past decade or two that rectify their input and make higher voltage, higher-frequency AC internally so that they can use a tiny transformer instead of the massive, heavy ones of older equipment. Same for aircraft as Syonyk pointed out- 400hz is USAF standard and the equipment onboard the aircraft is correspondingly lighter and smaller. I’m not sure if it’s a linear relationship or not, but if a 25hz transformer needs to be more than twice as big as a 60hz transformer for the same power, and a 1909 transformer needs to be some factor larger than a 2020 transformer owing to the available materials and techniques… then man, these transformers must have been huge. If my memory of 15hz as the single-phase AC traction frequency is accurate, then boy oh boy- those must have been some whoppers.
I was also curious about the discussion on having two overhead wires, and not three. Were they using the rails as the third conductor?
They go into discussion about ‘trolley wheels’ in context that makes me think that’s what was used to actually collect current from the overhead wires. I wonder what those looked like.
I, too, find the description of 200F cabin temperatures to be amazing. How did the engineers work? On threat of quitting if anyone every made them go back? And also in so much smoke and fume that the engine couldn’t get enough combustion air to maintain pressure! One statement is that the rear engine would drop to 70psi of steam from 200psi.
They discussed the amount of drag that the idle locomotive would add to the electric locomotive’s load- presumably this means all the steam equipment, valvegear, etc was engaged and turning like a giant jake brake any time the wheels were turning. I suppose it would have been a huge undertaking to retrofit every locomotive that would go through that tunnel with some kind of release.
They discussed regeneration quite a bit without actually saying where that power was going. Was the use of regeneration always timed to coincide with the ascent of another train so that the descending train could dump power onto the line to provide some of the power for the ascending train? I am not sure what would happen if a train tried to dump power back into this private grid where the only other thing on the line was the hydro dam- the train would be pushing frequency up and the synchronous generators at the dam would… what, overspeed since nothing was acting to resist the increase in frequency?
On hydro power: I think it’s interesting how a lot of environmental advocates today no longer count large hydro as renewable, due to its impact on local ecology. There’s a good podcast series by ‘Outside/In’ called “Powerline” about the proliferation of hydroelectric power in Quebec and its impact on wildlife and indigenous people. Oh well, we’ll have to build more nuclear, keep fossil fuels, or keep the lights off.
By 1900 all of the modern motors had been invented in their current forms, but not their current efficiencies, and the majority of their properties were well understood at that point (the air-gap importance was one of the major things they hadn’t worked out perfectly by then, but other than a decrease in efficiency, the behaviour and properties of the motors remained the same).
This is because if you need smaller conductors in an AC system you control, you just crank up the voltage. So it’s a non-issue, really.
Europe still uses 15kV single-phase 16.7Hz (it used to be 16 2/3 Hz precisely, but they changed it to slightly slew the zero crossing relative to their 50Hz AC mains) for many country’s train systems (Germany, notably).
Pretty much what you’d expect: Trolley pole - Wikipedia
As far as I’m aware these engines were never really designed to disconnect any of that for any purpose. Being towed was a situation of emergency and done only when necessary for the steam beasts. Do note, however, that the smaller engines were expected to have a coefficient similar to rolling stock, which implies that the mallets in particular had additional resistances that were unexpected. My guess is that due to the compound nature there may have been some internal coupling between the cylinder sets that was not able to be vented to the outside - shunting dead power back and forth there at atmospheric pressure may have had a much higher resistance than anticipated for shunting medium pressure blowby steam or something.
There was quite a bit of discussion a ways down talking about how the Italians had multiple trains on the same hydro power supply and that served as a buffer for accelerating trains as well as a utility for consuming the regenerated power - and in the main article there was a mention of what I gather was effectively a dump load directly into the lake which could serve as a dynamic braking load for the motor. This implies two things:
- The power generation equipment at the dam could not sink the power itself and
- There was nothing else to take the load.
Given that there was single track in the tunnel, this is unsurprising - they can’t run trains in both directions simultaneously. As for the dam generating equipment, this is also unsurprising. Water wheels have immense mass and the water flowing through them has immense inertia. They’re going to rumble at the same speed no matter what. And the generating equipment in those days mostly utilized water governors for speed control - they carefully balanced the load on the water wheel with the demand on the grid and there was a lag response time to it. Overspeed in those situations can often destroy the structure, and sudden load jumps is also damaging to the bearings and other equipment, due to the massive forces involved. Hence the dump load, which could be both quickly deployed but also variable in its effect according to the description (it reads like a pair of rods that were inserted into the lake water at varying depths. I shudder to think of the effect on any fish who happened to be swimming nearby…).
I’m firmly convinced that there can be ecologically ethical hydropower. I’m not convinced we’ve done a great job of it in most places. Québec has made a very good go of it, compared to many places like the US’s aggressive western dam system, and yes, dams always have a massive effect on the local ecology. In consideration with the demands of each area, compromises can be made that in the short term are easily adaptable for the wildlife and in the long term can contribute in similar manners to the local ecosystem as the original arrangement did. First Nations concerns are also valid, as usually one of the main criteria for dam location is “not where there’s money to be made on the land you’d otherwise drown”, which in many cases means First Nations land gets sunk and a more ecologically and ethically appropriate choice gets bypassed.
I don’t see an economic future for nuclear power, and we’ll keep fossil fuels until we can’t anymore, but verily, that day approacheth.
Carefully, I suppose. I’ve no idea how humans work in 200F temps, because that’s well into damaging flesh, though if you’re well insulated in engineer gear…
Tunnels have always been hard, but that’s certainly the worst tunnel conditions I’ve heard of (if they’re not, you know, actively on fire).
A steam locomotive being pulled is basically the same as a locomotive going down a hill - wheels driving the cylinders. This is referred to as “drifting” in most steam literature, and appears to be one of those “holy wars” between engineers, designers, operators, etc, in the mechanisms to deal with it. Going down a hill, locomotive drag was generally a feature to help hold the train without friction brakes, so reducing the drag wasn’t a big concern.
However, if you just close the throttle/regulator and let it run, you’ll end up with a vacuum in the cylinders that sucks stuff from the smokebox back through the blastpipes and generally ends up with ash, embers, and other crap into the cylinders, which scores them up and does an awful lot of damage in short order. Some systems have a one way check valve that lets you pull ambient clean air into the cylinders, which works except for those valves tend to leak steam eventually and the oxygen can cause rapid oxidation of oil in the cylinders, which eventually also causes problems.
Some places would just leave the regulator/throttle cracked open to keep some minimal positive steam pressure in the cylinders, and to help keep them up to temperature. I believe some locomotives may have used a bypass valve to let the sides of the piston communicate with one another, but there were then issues with heat buildup and such.
This wouldn’t be quite as much of an issue if the firebox was dumped and there wasn’t steam - you could let it just pull through the boiler, likely, but I don’t know if there would be vacuum issues eventually. It’s just not something they were really designed for. But I would be inclined to believe that it takes an awful lot of force to pull a Mallet with no steam.
It wasn’t clear what particular iteration of Mallets they were using to me, but in general, a Mallet is going to have both high pressure and low pressure cylinders - they’re big (ranging to massive) compound steam locomotives with two articulated sets of drivers.
It’s discussed somewhere in the paper. There’s a frequency controlled dump load back at the dam - if the frequency rises up from the specified target frequency, they start running rods into a water based load (it wasn’t clear to me if they just dumped it into the lake, but the water load banks I’ve known were contained).
It’s a bit off topic, but the Deep Green Resistance people are among the small group of modern “environmentalists” I consider actually self consistent. The rest insist that we can’t have nuclear, can’t have dams, can’t have solar farms because the desert tortoise might live there, etc, but that somehow we can magically keep all the power we want, on demand, for cheap, with no carbon emissions, because, well, darn it, they can’t imagine any alternative.
I just came across this thread and began reading the article linked. Apologies for reviving a dead thread, but I’m reminded of two personal experiences from the last 12 years:
Firstly, I’ve stayed in an old hotel/hostel in Skykomish. My wife’s friend was getting married in Leavenworth, and we flew into SeaTac at 8pm and stopped in Skykomish on the way to the wedding. That whole town was terribly polluted by the railroad in the 1920s-1970s with waste oil and heavy metals. Oil change procedures were apparently “pull the engine over there, dump the oil in the dirt, and put in new stuff.” They apparently dug up 20ft under most of the town, and up to 100ft in some places to get rid off all the contamination. Picture moving a town out of the way for a few years and then putting in back when the bad dirt is gone.
The other one was a few years later. I was between jobs with a baby on the way, so I went to New Zealand for a month. On the South Island they have a scenic train that runs from Greymouth to Christchurch. That train was electrified until NZ had their wave of privatization ala Thatcher. The company which bought out the government scrapped the copper, etc. (making a tidy profit) and replaced them with crappy diesels. Now the open observation decks have to be closed while in the tunnel, and smell of diesel fumes even when out of the tunnel. Late stage capitalism even then. I should note that this narrative may not be totally true; the privateers’ said the electric stock and wiring were worn out and needed to be replaced and diesel was the only affordable alternative. But my guess is those catenaries were good for decades more.
It was that and then some. The protocol for refuelling large diesel tanks was ‘stick the nozzle in the tank cap and go to lunch’. The tank may or may not be full and overflowing when they got back. Yes really. Unfathomable levels of IDGAF going on there.
So the end result is that the dirt under Skykomish is indeed no longer original to the town.