16 ms·
Indeed. Maybe a new generation of aluminum wire could be better. But for big feeder wires, it’s a different story. Compare: 2 AWG XHHW-2 Al: 0.358 inches OD,
by amluto 4y ago
Indeed. Maybe a new generation of aluminum wire could be better.
But for big feeder wires, it’s a different story. Compare:
2 AWG XHHW-2 Al: 0.358 inches OD, 0.081 lbs per ft, $0.90/ft
4 AWG XHHW-2 Cu: 0.33 inches OD, 0.129 lbs per ft, $1.78/ft
I know which one I would pick under most circumstances. And insurance companies are just fine with the aluminum option.
- dboreham 4y agoUSA could also transition to a proper mains voltage like much of the rest of the planet.
- chiph 4y ago230/240v does have it's advantages, primarily being able to use smaller diameter wire for the same current carrying capacity. But 50 Hz as a system frequency is just wrong. It results in oddities like running your railroad at 16-2/3 Hz.
- eru 4y agoI'm not sure what's so odd about running your railroad at 50/3 Hz? Do you not like rational numbers? (I guess you are talking about three-phase power in general, or is there anything special about railroads?) In practice, just like everything in engineering, you don't run your grid at 50 Hz nor your railroad at 50/3 Hz. You run the grid at some frequency that varies slightly around 50Hz. There's always engineering tolerances. So even if you don't like rational numbers, it doesn't really matter whether you run the railroads at 50/3 +-0.01 Hz, or at 16.66 +-0.01 Hz. (I don't know how tight the tolerances are in practice here. It doesn't matter for the argument.)
- lazide 4y agoRational numbers are a lot more work than integers. Also, 60 is a common base for several things (degrees, time), which interact with the grid in numerous ways. It’s convenient to have them match.
- eru 4y agoJust express everything in micro-Hertz and you can use integers just fine. (If you need more precision, go for nano-Hertz..)
- iggldiggl 4y ago> In practice, just like everything in engineering, you don't run your grid at 50 Hz nor your railroad at 50/3 Hz. You run the grid at some frequency that varies slightly around 50Hz. There's always engineering tolerances. > So even if you don't like rational numbers, it doesn't really matter whether you run the railroads at 50/3 +-0.01 Hz, or at 16.66 +-0.01 Hz. In practice the nominal frequency was changed to 16.7 Hz anyway due to some weird edge case created when running motor-generators [1] for prolonged periods of time at exactly the nominal 3:1 frequency conversion ratio. (See https://de.wikipedia.org/wiki/Bahnstrom#16_2%E2%81%843_Hz_gegen%C3%BCber_16,7_Hz https://de.wikipedia.org/wiki/Bahnstrom#16_2%E2%81%843_Hz_ge... and use an online translator at your own peril if necessary.) [1] These days, newly built (or probably occasionally re-built) substations prefer to use solid-state frequency converters, which are immune to this particular problem, but there still are enough of the older motor-generator sets around, too. Wikipedia also claims that motor-generator sets are more tolerant against earth faults, which might or might not preclude against getting rid of all of them even long-term.
- jabl 4y ago> It results in oddities like running your railroad at 16-2/3 Hz. 50 Hz railway systems are probably more common than 50/3, at least in Europe: https://en.wikipedia.org/wiki/Railway_electrification_system#/media/File:Europe_rail_electrification_en.svg https://en.wikipedia.org/wiki/Railway_electrification_system... 25 kV AC 50 Hz (60 Hz in countries using such grid frequency) is the modern standard: https://en.wikipedia.org/wiki/25_kV_AC_railway_electrification https://en.wikipedia.org/wiki/25_kV_AC_railway_electrificati...
- thulle 4y agoHow does a 50 Hz system frequency result in railroads running at 1000/60 Hz?
- iggldiggl 4y agoFor hysterical raisins: Before the advent of power electronics, which allowed three phase asynchronous motors to proliferate, commutated series-wound motors were the railway motor because of their beneficial characteristics (quoting Wikipedia: "high starting torque, can run at high speed, and are lightweight and compact"). A classic commutated series-wound motor is a DC machine. The problem with DC power is that without power electronics, you can't really change the voltage (except downwards by wasteful resistors), so your transmission voltage is limited by your maximum motor voltage and you incur relatively high transmission losses and need frequent substations every few kilometres. (Mainline railways can cheat a bit by equipping all of their rolling stock with two (or occasionally more) motors permanently linked together in series, so each motor only gets a fraction of the voltage, but you can take that approach only so far…) So you want to switch to AC power, which is more efficient because it can be easily transformed up and then down again, because transformers can actually be made small enough to fit into a locomotive. Fortunately with some adaptations a series-wound motor can be made to work on AC, too, but there are some trade-offs depending on the required amount of power and the frequency. I.e. the motor still works better if your AC current is more "DC-like", i.e. doesn't have too high a frequency. It turns out that for something more modest like a hoover or a domestic power drill, an AC series-wound motor ("universal motor") will work fine enough even at 50 or 60 Hz, but for railway purposes with their somewhat higher power demands things didn't work so well. Because at that time power electronics didn't exist or were still in their infancy (e.g. mercury arc rectifiers), there was no possibility of doing anything useful on board of the locomotive, so instead it was decided to reduce the frequency of the railway's power supply system, because at 16 2/3 or perhaps even 25 Hz motors could still be made to work reasonably enough. Also at that time changing the frequency meant using a motor-generator set, and presumably choosing some simple integer ratio for the two frequencies also simplified things. By the time other countries started considering switching to AC electrification, usable rectifiers existed that could be used on locomotives, so those countries could electrify at the full 50 or 60 Hz and then rectify the current to DC on board of the locomotive, thereby sidestepping the problems of running a commutated series-wound motor with AC power. Even later on we then got fully variable voltage and frequency inverters, which finally allowed serious usage of (usually asynchronous) three-phase induction motors. (Some railways used three-phase drives even before that, but without modern electronics this was a somewhat more cumbersome prospect, see e.g. https://en.wikipedia.org/wiki/K%C3%A1lm%C3%A1n_Kand%C3%B3 https://en.wikipedia.org/wiki/K%C3%A1lm%C3%A1n_Kand%C3%B3)
- xvedejas 4y agoSplit phase means we get the choice of 120V (for safety) and 240V when we really need it (eg appliances)
- jabl 4y agoWhere I live it's fairly common for houses to have 230V single phase for most things, and then 400V three phase for things needing more power.
- petre 4y agoHow do you resolve phase imbalances? Most generators are 3 phase. The system is othrewise well designed to use one or two phases when needed. We use one or three phass in Europe.
- eru 4y agoDifferent circuits in a single American household use different phases, I think.
- Scoundreller 4y agoCorrect. Fun times trying to figure out why your power-line networking doesn't work. The heavy load stuff is 240V anyway.
- petre 4y agoSo it's the same way we do it in Europe with single phase, but I think it's easier to split three phases between single phase loads (most AC loads in a hosehold), rather than three phases between two phase loads (a few AC loads in a household). I still like the 120V plug connector with a key on the hot wire. In Europe I always wire the hot on the right hand side of the Schuko socket, as most standards have it on the right.
- eru 4y agoAmerican outlets and plugs are barely usable. They go live even when you don't completely plug them in, yet. The British plug is a pretty decent design from an electrical safety point of view. (However, they turn into caltrops in the dark.)
- xyzzyz 4y agoAluminum wiring woes is as much of a problem in parts of Europe I am from as it is in the States.
- neither_color 4y agoJust because the US isn't on the metric system doesn't mean that every single standard we adopt is inherently wrong. Hating on our electricity is one of the silliest things I can think of. In my house the only thing that needs 240V are kitchen appliances, A/C and a car charging outlet, those get circuit breakers that tap both phases. Everything else gets one phase. The way more and more appliances and light fixtures(LED > CFL) are trending towards high efficiency and solar even 120V is more than necessary.
- maeln 4y agoIf there is anything to change, it is the horribly dangerous electric socket. I was also shocked to see that many house still doesn't use differential circuit breakers. I guess using 120V reduce the risk of a fatal electric shock, but I still wouldn't trust any installation that doesn't use differential circuit breakers.
- manfre 4y agoBuilding codes only require upgrading the home's electrical when doing certain types of repairs/renovations. Newer homes will have afci or gfci breakers on most circuits.
- mortehu 4y agoDon't forget kettles and space heaters. Also, visiting vacation homes or cabins where the owner doesn't have an electric car leads to very long charge times.
- yjftsjthsd-h 4y agoWhat would be better and how would it fix this issue?
- coreyp_1 4y agoThere's a lot of misconceptions about US electricity. This video does a nice job at pointing out the good and the bad. https://www.youtube.com/watch?v=jMmUoZh3Hq4&ab_channel=TechnologyConnections https://www.youtube.com/watch?v=jMmUoZh3Hq4&ab_channel=Techn...
- a9h74j 4y agoSo after the next revolution it will all be 100V or 1000V (and a week will be 10 days)?
- strbean 4y ago128V ftw.
- a9h74j 4y agoAnd for an upper limit: 18000V / 137 = 131.4V
- eru 4y agoOf course, not. That would be silly. The Volt is an arbitrary unit. After the revolution, we'd be using natural units. https://en.wikipedia.org/wiki/Natural_units https://en.wikipedia.org/wiki/Natural_units Basically, you'd express things in terms of speed of light, electron charge, planck length etc. In this case, [Planck energy / electron charge] might be an appropriate unit. (It would also be a pretty useless unit, because it's absurdly large compared to everyday voltages.) See also https://en.wikipedia.org/wiki/Planck_units https://en.wikipedia.org/wiki/Planck_units
- a9h74j 4y agoPretty sure that David Graber demonstrated that there have been societies which used Natural units.
- imtringued 4y agoAncient Egypt apparently used something very similar to the meter.
- towaway15463 4y agoHow is it a different story? Those wires still need to terminate and will oxidize at the connections and produce a lot of heat.
- Ottolay 4y agoYou can take precautions to avoid the oxidation. This is already done reliably on airplanes and in overhead power distribution, where aluminum wire is the standard.
- lazide 4y agoWhich is relatively expensive and error prone, compared to copper connections. For service connections and large scale power distribution where trained professionals are already required and lack of maintenance is already a fire hazard, it isn't a problem. For small branch circuits where work is often done by random Joe's and where any sort of preventative maintenance is few and far between, it is a failed experiment.
- strbean 4y agoAssuming copper prices continue to outpace aluminum prices, eventually copper will be the expensive option vs. aluminum (done right). Not sure if the error prone aspect could be remedied though.
- lazide 4y agoCompared to electrician labor? It would have to be price at silver prices to matter; most likely. Either way, home and commercial construction is likely to crater (already starting in many areas) due to cost of $$ going up, so that should help tamp down demand quite a bit.
- Cerium 4y agoIn addition to the other mentioned reasons, larger gauge wire is commonly terminated in blocks rather than at end points and likely won't be touched after initial installation, compared with branch circuits which will have their outlets or switches changed multiple times and often without professional assistance.
- baskethead 4y agoAluminum wiring is the thalidomide of the construction industry. No matter how much you improve it, you will never get over the stigma. No one will buy a house with state-of-the-art aluminum wiring just like no one will ever take thalidomide, even though they know exactly what caused the birth defect issue (chiral molecules that were created during the manufacturing process).
- josephcsible 4y agoBut people do still take thalidomide today, just not pregnant women, and only along with contraception.
- eru 4y agoFrom what I could learn from Wikipedia, it seems it's much less widely used than it would be without the bad reputation. In addition, German Wikipedia mentions some extra paperwork and hassle German doctors have to jump through if they want to prescribe.
- freeqaz 4y agoWikipedia straight up says "thalidomide causes birth defects." Could you please cite where you found this info? I might take a stab at updating the article if it's a legit source. Thanks!
- mb5 4y agoIt's not just stigma with thalidomide - the two forms of the molecule interconvert in the body. So even a dose of 100% pure R-thalidomide (the useful kind) will invert into its mirror image, L-thalidomide (the harmful kind), and will approach a 50:50 mix. As the sibling comment says, it's still used in cases where there's little to no chance of pregnancy, because we don't know another way to make it safe.
- ars 4y ago> Maybe a new generation of aluminum wire could be better. It already is better, this is VERY old news. Modern aluminum alloys do NOT have this problem, but it's too late, no one wants to think about aluminum wires.
- stjohnswarts 4y agothey will if it goes up 10-20x its current cost (adjusted for inflation of the time). that's the beauty of the market, it forces you to try new things not to go bankrupt.