[HN Gopher] Electric ferry uses a long extension cord [video] ___________________________________________________________________ Electric ferry uses a long extension cord [video] Author : zdw Score : 159 points Date : 2022-11-15 16:42 UTC (1 days ago) (HTM) web link (www.youtube.com) (TXT) w3m dump (www.youtube.com) | MichaelCollins wrote: | Did anybody else know this would be a Tom Scott video before | clicking it? He always finds the oddest most interesting things | to show off. | Aardwolf wrote: | Yes! I expected "this is going to be a Tom Scott video" before | clicking the link. He has a niche in interesting esoteric | infrastructure. | daneel_w wrote: | Sort of common in the nordics. We have lots of them in Sweden, | the self-service type for short crossings to sparsely populated | islands, but the power cable usually drives a winch attached to a | steel cable. | zwieback wrote: | We have 3 electrical ferries in Oregon crossing the Willamette | but they use 3 overhead wires to deliver 3phase AC. Works great | for short hops. | pinot wrote: | https://img.atlasobscura.com/dmMEj9y780YXqaTupI_kf8Iin74JjtD... | | For example, the Canby ferry | todd3834 wrote: | This is pretty cool. I wonder what the effort would have been to | instead have a battery charging / swapping process on one end. It | would still be clean energy, charged on shore. I'm sure the | batteries wouldn't be super light but you could have them in | modules and you could engineer solutions for moving them. | | Perhaps for situations where it isn't already cable guided this | is still a practical approach. I'm pretty ignorant when it comes | to the weight of the batteries and how much energy they can | provide + etc... but if my Tesla is any indicator it doesn't seem | too hard vs managing that cable back and forth | Thlom wrote: | Around a quarter of the ferry crossings in Norway are | electrified. Usually there's one or two electric ferries and | one diesel ferry. They charge while unloading and loading and | during the night when there's fewer crossings. Before they had | to take breaks during the day to charge, but now days I think | they run all day. | todd3834 wrote: | The batteries could even be attached cars themselves so moving | them on and off would be really simple | hawski wrote: | Or with a thicker cable they could charge cars while they | cross the channel. | [deleted] | chowells wrote: | Rechargeable batteries are not 100% efficient. I'd put good | odds on this system being cheaper. | bentcorner wrote: | The captain said they use 150-200kwh a day, which would be | around 2-3 EV batteries' worth (Model S has a 100kwh battery). | That's split up between 88 trips, so there's plenty of | opportunity to swap batteries. | | So they could probably have some kind of battery system but I'm | guessing since it's already "tethered" with a line just to | cross, stringing an electrical cable was already easy to do and | has simpler logistics than managing batteries. | Epa095 wrote: | For those interested in this, there is also a quite large battery | powered ferry operating in Norway. | | >The Basto Electric is 139.2-metre-long and 21-metre-wide and was | built by the Turkish Sefine Shipyard and has room for 600 | passengers and 200 cars or 24 trucks. | | >Basto Electric uses batteries with a capacity of 4.3 MWh. The | fast-charging system has a capacity of 9 MW. | | https://www.electrive.com/2021/03/02/worlds-largest-electric... | Thlom wrote: | Around a quarter of all ferry connections in Norway have been | electrified. Often there's one electric and one regular diesel | ferry operating in tandem. Basto Electric is still the biggest | one though. | mstade wrote: | While not fully electric, there's also the Color Line ferry | operating between Sandefjord and Stromstad[0]. I happened it | be in town for its inaugural voyage and it turned out to be a | quaint little trip. As far as I understand it though, they | more or less only run on electric power when navigating out | of port, and back to diesel when at see and arriving. | Enjoyable trip nonetheless! | | [0]: https://www.colorline.com/sandefjord-stroemstad/color- | hybrid | mywacaday wrote: | While Norway is to be admired I find it difficult to see | their experience as applicable to the rest of the world when | they have a 1.19 Trillion wealth fund which equates to over | 22 million per person in Norway. | throwayyy479087 wrote: | America invented the airplane then went to the moon. We | started every large tech company. We essentially created or | popularized everything that defines the modern era. | | Excuses are why infrastructure and politics here sucks. We | should bully the federal government for their failure here, | just like Biden bullied LGA into renovating | transportgo wrote: | It's actually $220,000 pr person. | encoderer wrote: | Sort of off topic but the war in Ukraine has brought to my | attention that we actually fire missiles with giant miles-long | extension cords. Missiles. With extension cords. | sidewndr46 wrote: | I think those are just for control & telemetry. The actual | missile has a battery on it usually. | hnlmorg wrote: | Anyone got a source for this? I'd be interested to learn more | modeless wrote: | https://en.wikipedia.org/wiki/Wire-guided_missile | | I think the TOW missile is the most prominent example. | adwww wrote: | MILAN is very slightly older and probably just as widely | used - especially out of US. | nuccy wrote: | Those are wire-guided missiles, usually used to destroy tanks | and other armed vehicles. The length of the wire is just few | kilometers. The wire is needed to actually tell the rocket | where to steer [1]. | | More modern approach to anti-tank missiles are those with | lasers being used for highlighting the target [2], while the | missile has a battery and a camera to find the spot. The | other approach is to do on-the-fly image recognition [3]. | | Edit: interesting fact: DART space craft sent by NASA to hit | an asteroid used a missile derived technology to recognize | the image and steer itself into the target, since direct | control from Earth was not possible due to communication lag | [4] (also try googling "dart mission" to see google's doodle | on the topic). | | 1. https://en.wikipedia.org/wiki/Wire-guided_missile | | 2. https://en.wikipedia.org/wiki/Laser-guided_bomb | | 3. https://en.wikipedia.org/wiki/FGM-148_Javelin | | 4. https://www.nasa.gov/press-release/nasa-confirms-dart- | missio... | stavros wrote: | Wait, what? Why? | NwtnsMthd wrote: | - Can't be jammed | | - Simple | | - No radio frequency indication of an incoming missile. | | There must be other reasons as well. | stavros wrote: | I agree with the first and last point, but reliably | unrolling a 4km wire while going 500 kmh cannot be simple. | MarkMarine wrote: | They seem to work quite effectively, I've never seen a | TOW fail. Downside is you need to maintain visual | guidance of the missile through it's whole flight path. | SketchySeaBeast wrote: | I'm envision that classic "look down and see a pile of | rope unspooling around your leg right before you | disappear out of frame" shtick. | supergeek wrote: | Anyone involved in RC aircraft will gladly tell you that | getting a stable radio link for video and control past | 4km is anything but simple. | | Even a basic analog video signal is orders of magnitude | more data than what you'd be transmitting in a phone | call. | encoderer wrote: | Isn't it crazy how much effort we still spend as a race | trying to kill each other. | jedc wrote: | Also torpedos (for example, from submarines) | simon_000666 wrote: | Cool - another option could be beaming power to the ferry using | microwaves, millimeter waves or lasers. The power transfer | efficiency would be lower but saves the cable complexity and | slacking/maintenance. | MarkMarine wrote: | I think the losses on both sides of that invisible death ray | would be more complex than a long extension cord. | jguimont wrote: | For those mega cargo ships, why is civil nuclear power vessels | are not a thing? Seems they would massively reduce the footprint | while providing better clearner power. | coryrc wrote: | Because they don't pay for pollution. | Gwypaas wrote: | Because it's all about cost. Those 400m container ships are ran | by a low cost crew of 15-25 with some 3rd party maintenance | personnel sprinkled in. Try fitting a more expensive fuel and | more maintenance into that. On top of all safety concerns. | | For ocean crossing vessels they are more closely looking at | e-fuels and hydrogen since that gives the same benefitd at | cheaper cost with not a too large change in the shore side | infrastructure. | Markoff wrote: | https://youtube.com/watch?v=cYj4F_cyiJI | mediaman wrote: | Servicing marine nuclear reactor units requires very special | skills and is expensive. So is the initial capital cost. | Servicing large marine diesel systems uses labor that is much | more available globally. | expazl wrote: | With this setup I wonder why even have the motor on the ship? | It's using an extension cord to get power to the ship so it can | pull on the wire guides, but you might as well just have put the | engine pulling the wire on the shore and have a "dumb" platform | in place of the boat. | AdamJacobMuller wrote: | The wire would need to be parallel to the water at just above | or below it and would always obstruct other traffic. This | arrangement allows the wire to fall onto the seabed so ships | can easily pass in front of and behind the ship, given | reasonable clearances. | TheRealPomax wrote: | You want the engine in a place where the people who need to | control it, or even kill it in an emergency, can feel what the | engine's doing, and have control over that engine. | willcipriano wrote: | If I was in Hollywood I'd call Tom Scott and give him whatever he | needs to make whatever he wants. Imagine something like a long | form road trip documentary, stopping in at interesting places and | doing interesting things but with the pull and budget of a studio | behind him. | DaiPlusPlus wrote: | > If I was in Hollywood... | | Hollywood essentially destroys almost everything it touches: | the people that invest in film production insist on maximising | their RoI at the cost of petty things like artistic integrity, | historical accuracy, and such. | | I enjoy independent video producers ("creators" is the term | now, I gather?) on YouTube (and Vimeo, etc) like Tom Scott | precisely because _it isn 't_ Hollywood. | yreg wrote: | What does he need the pull and budget of a studio for? | adamparsons wrote: | He has mentioned a few times now that he struggles with | developing ideas and script writing, and is essentially | bottlenecking his pipeline. I'd imagine a well picked writing | team that doesn't lose sight of what makes his content great | would be welcome, but also I don't doubt over the years he's | explored this at length already | willcipriano wrote: | My grandparents made a documentary years ago[0], they started | on their own and interviewed the family but once HBO got | involved in the project they were able to do things like get | into the courtroom for a parole hearing. Few people would | talk to them, but the same people would bend over backwards | for HBO. | | [0]https://m.imdb.com/title/tt1024663/ | paxys wrote: | There is a long line of very popular YouTube stars who have | tried to transition to making more "mainstream" entertainment | content (TV, movies) and have failed spectacularly. Large | YouTube channels have fine tuned all aspects of their | production to be surfaced by YouTube algorithms and consumed by | YouTube audiences. Making engaging content for Netflix/HBO or a | movie theater is a completely different problem. | MarcelOlsz wrote: | Just upload it on YouTube. Problem solved. | adamparsons wrote: | Yeah whenever I've seen a favourite creator put up an out- | of-place piece of long form content, it sometimes even gets | a calendar entry so I can give it my full attention later | dredmorbius wrote: | Electrified marine transport is an interesting challenge, though | there are a few options available. | | Notably, canal and river traffic _can_ rely on electric traction | provided by onshore "mules". | | _That_ terminology is borrowed from the original practice of | having mules haul barges along canals, _and_ reveals the immense | enhancement in efficiency of water-borne transport. A single mule | _might_ haul a cart weighing a tonne or so across level land (and | far less climbing any sort of grade). The same mule could haul a | barge on a flat and still canal carrying 20--40 tonnes of cargo | or passengers. | | For passengers, the comfort of canal travel (no jostles, bumps, | or broken axles as with a coach) was an immense improvement. The | effect of the Erie Canal, a four-foot-deep (1.2 m) ditch from the | Hudson river to Lake Erie was immense in opening up the US | interior in 1825. Further, canals and their locks mean that the | work of lifting (or lowering) cargo is done by the "roadbed) (the | river) itself. In the case of the Erie Canal, 172m (565 ft) of | elevation gain in net. | Someone wrote: | > That terminology is borrowed from the original practice of | having mules haul barges along canals | | The Panama Canal has mechanical mules, but they are only used | to keep ships on course, not to propel ships | (https://en.wikipedia.org/wiki/Panama_Canal_locks#Mules) | | Disadvantages of towing are that it requires a towpath | alongside the water, that overtaking is difficult, and that | making tight turns can be difficult (the puller always pulls | the ship closer to the canal or river shore, requiring the use | of the ship's rudder to keep it on track. In tight turns, the | pull direction is closer to orthogonal to the shore, requiring | more rudder) | | Because of these, I think battery-powered ships with container- | sized batteries that can easily be swapped may be a better | solution. | joak wrote: | Small fusion generators. | | TAE, helion energy and ZAP energy are 3 well founded companies | (combined $1B+) aiming at building ~50MW generators based on | non-tokamak fusion. | | The generators are small enough to fit on a truck and could | easily power the biggest container ships. | dtgriscom wrote: | "are small enough" => "would be small enough" | dredmorbius wrote: | If you've got the ability to build fusion generators, you've | got the ability to create carbon-neutral analogues of | existing fuels. | | You've also got that ability _without_ nuclear inputs, from | conventional renewables (solar, wind, geothermal). | | Those fuels can be far cleaner than bunker fuel, and a diesel | or kerosene analogue burning in a well-tuned ICE or turbine | would have limited negative effects. The marine-propulsion | pollutants of most significant concern, aside from (fossil) | CO2 are particulate, NOx, and SOx emissions. | | All are far more prevalent with heavier fuels, and are | concentrated largely along shipping lanes far out to sea, | other than at ports. These tend to settle out / mitigate | reasonably quickly, and I believe their long-term ecological | impacts are fairly minimal. | | The problems with nuclear marine propulsion are many, not the | least of which are the 100--200 shipwrecks logged every | decade or so, though you can add to that risks of piracy or | terrorism involving nuclear propulsion. Keep in mind that | present commercial fleets are on the order of _eight | thousand_ vessels. We 've had experience with only about four | _hundred_ nuclear-powered vessels, virtually all military | ships, of which about 170 are presently operational. The | exceptions are three demonstration commercial vessels, the | _Otto Hahn_ , _Savannah_ , and _Mutsu_ , all of which failed | to prove feasible, and a handful of Soviet-era icebreakers, | now operated by Russia. | | Fusion itself remains both technically and economically | infeasable for any foreseeable future. | | <https://old.reddit.com/r/dredmorbius/comments/3c52ll/shippin | ...> | js2 wrote: | This is the origin of the term towpath: | | https://en.wikipedia.org/wiki/Towpath | azepoi wrote: | https://en.wikipedia.org/wiki/Chain_boat_navigation | | Not a new idea: Chevaux electriques, meaning "Electric horses" | (electric towpath tractors, halage=tow). | | https://de.wikipedia.org/wiki/Treideln#/media/Datei:Courchel... | | https://de.wikipedia.org/wiki/Treidellokomotive | | http://ronfleur.centerblog.net/6408563-halage-des-peniches-p... | | https://www.ronquieres.org/le-village-de-ronquieres/vieilles... | (last image bottom right) | | http://www.traitsensavoie.fr/spip.php?article308 | | http://www.traitsensavoie.fr/IMG/jpg/cheval_electrique_bethu... | | http://papidema.fr/traction_vn_extra.php#chevaux-elec | dredmorbius wrote: | _Not a new idea..._ | | FWIW: I wasn't claiming that. | tpmx wrote: | I think this ferry between Helsingborg (Sweden) and Helsingor | (Denmark) does it in the coolest way. Since 2018 the ferry has | been running on batteries. Whenever it docks into any of the two | ports, an ABB robot connects the charging cable. | | One real cool thing here is that they have gotten it to work for | 4 full years in a northern climate. That means a lot of extreme | weather edge cases. | | https://youtu.be/l93i87pZWhY?t=13 | tjoff wrote: | When I clicked on this I thought, why not just have a cable- | guided ferry instead? (Which already is a common thing) I assumed | they'd have to make maneuvers not possible with a cable. But it | already is?! | | Then why not just tug the cable instead, much better efficiency | then propellers. | | Edit: ok, it is. Though what I've seen is that the motors are | pulled from shore rather than on the boat. Which seems simpler, | but this is maybe easier to retrofit. | distrill wrote: | I have to admit, it sounds a lot crazier before you learn that | there are already cables running along the channel that the boat | uses. This also means that this can't generalize outside of | channels that already have cabled crossings. | | Given that constraint, I wonder about operating these ferries | more like a ski lift then. If we're already stringing cables | across the channel might it make more sense to keep them on shore | away from the water? | newpavlov wrote: | Why not simply pull the ferry using the steel cables? In other | words, put traction systems on both riversides and move the ferry | using them. It even should be more efficient than a propeller- | based propulsion system. | matsur wrote: | The ferry in the video uses cable based propulsion. | bbstats wrote: | This is why hn needs a downvote button LOL | javawizard wrote: | HN has one, it's just only accessible to those who have | reached a karma threshold (501 I believe). | javawizard wrote: | It pulls itself along the cables rather than using a | propeller, yes, but the motor that's doing the pulling is on | the ferry rather than on the shore. | | To answer GP's question: I don't know, but given that this | was a retrofit of an existing diesel-powered ferry I could | guess that this was the cheaper way of doing it. | nippoo wrote: | Yes, but the propulsion is on the boat rather than at | shoreside like OP suggested (ie the cables are static) | [deleted] | w-ll wrote: | So it doesnt have a cable spanning the river all the time. | newpavlov wrote: | But it does have two cables spanning the river all the time. | IIUC they get relaxed when ferry does not move and sink to | the bottom to allow other ships to pass. | clouddrover wrote: | They say the ferry uses 150-200 kWh a day. If those numbers are | right that wouldn't be a very big battery pack. The Hummer EV, | for example, has a 212 kWh usable pack: | | https://www.youtube.com/watch?v=ORKuZxrFr6A | | https://www.youtube.com/watch?v=F9IUOR8lG3E | | Still, it's a cabled ferry anyhow so also having a power cable | makes sense. | oh_sigh wrote: | Notably, this ferry is driven on a chain which crossed the | channel already. | | I suspect they would have gone for batteries if the route wasn't | already anchored in | ok_dad wrote: | Yea, they only use 150-200 kWh per day, that's not a lot of | batteries to store on a large ship like that (it's like ~5-10 | EVs worth of batteries maybe? not the whole car, just the | batteries!), even if you couldn't charge between sailings | (which you could). I think it was probably a cost thing, too, | as this system with a cable is probably way cheaper than | batteries. | | edit: I was trying to reinforce here that, although this | application could easily have used batteries due to the low | energy needed per day, it didn't because there was a better | solution due to the pre-existing cable infrastructure. | Certainly this cable method isn't useful for most ferries, and | most ferries will be traveling further and faster and require | way more batteries. | karamanolev wrote: | They use so little because the use the (steel) cable for | traction (as I understand it) and not water. If they had to | use a propeller in the water to cross a river, the | consumption would be much more. | | So in essence, there's symbiosis between electricity and | running a cable-guided ferry. Otherwise you'd need more | energy, therefore bigger batteries, etc. | rz2k wrote: | When he mentioned the steel cable, I wondered why they | don't use an arrangement more like cable cars. It sounded | like it is in case they break loose during a storm or | emergency, so it useful to have the engine on board along | with the back up generators. | | Are the cables actually used for traction, or just a | countermeasure against having to fight the cross current? | ricksunny wrote: | I was also wondering this, you beat me to asking. If | there is precedent for two cables why not connect them to | make a long narrow loop of them like on a ski-lift; place | an electric-powered winch on one end and an idler on the | other? | | Was neat to see the video, and I'm sure they have their | reasons. | matsemann wrote: | One reason may be that the cable sinks to the ground, | which makes it possible for other boats to cross. If it | was like a ski lift, the cable had to be more tensioned I | guess, thus obstructing? | ok_dad wrote: | Yea, they pull themselves along the cable. The commenter | above you was correct, it is way more efficient than | props, plus it's way more efficient for high currents | like this river. My comment was simply that they _could_ | have used batteries, but for this particular application | a cable was perfect. I was reinforcing that this was a | great confluence of constraints that enabled this. | algo_trader wrote: | I really dont think so. | | There are just crossing 500m at 2-3 knots several times a | day. | | This is basically less than a semi rolling resistance which | is maybe 1/5kwh/km? | | EDIT: even so, x10 batteries 2mwh are still very reasonable | for a boat which cycle daily | brink wrote: | > it's like ~5-10 EVs worth of batteries maybe? not the whole | car, just the batteries! | | Batteries are heavy, batteries need recharging, batteries can | explode, batteries wear out, batteries cost a lot to | replace.. or you can have a cable that might snag, but | probably won't if you keep tension on it. | dredmorbius wrote: | And batteries in marine environments age much more quickly | than those in dry-land applications. Salt loves anodes and | cathodes. | yafbum wrote: | Also safety, I'd guess. Fire has much worse consequences on | ships than on land... | rz2k wrote: | Furthermore you could charge them during the middle of the | day and at night, and use the batteries during morning and | evening commutes, which is pretty ideal. | | As for the additional mass and displacement, the video | mentions boats having to push water out of the way, but water | also fills in behind the boat, so there isn't as much | physical work involved as it sounds like. | ortusdux wrote: | The Ford F150 Lightning comes with either 98kWh or 131kWh of | batteries depending on the package. | hathawsh wrote: | Wait a minute... in theory, there could be a ferry that | depends on power from an electric vehicle driven onto the | ferry. That would solve the logistics problem of moving | heavy batteries on and off the ship. The ferry could | initially use consumer vehicles and switch to customized | vehicles when the economics make sense. | l1tany11 wrote: | Some teslas have 100kwh batteries. The Hummer EV has ~200kwh | battery. Depending on how much extra capacity is needed to | optimize for longevity of the pack, and charging, it might be | far less than 10 cars worth of batteries. Potentially as | little as 1. | | Makes you think that there might be quite a few river ferries | that could be converted quite economically. | martinmunk wrote: | Worth noting is, the subtitles said "The ferry uses, each | day, about 150-200 kWh" whereas the speaker said "the ferry | uses today between 150 and 200kW". I'm guessing Tom Scott had | him clarify later, but the units, and what could be assumed | to be a timeframe or not, is not the same. | hnlmorg wrote: | I found this video about another type of crossing using a cable: | | https://youtube.com/watch?v=OW24yLHmC20 | rmason wrote: | I've ridden on one of those boats when I was in Basel. It was | incredibly calming to cross the river with no noise from a | motor. | | There are also I think five different cable cars in the | immediate Basel area that offer some incredible views as well. | hnlmorg wrote: | You've now convinced me that I need to Basel :) | gpvos wrote: | There is a link below the video to a Wikipedia article with | similar ferries all over the world. | rmason wrote: | Though I am a big fan of Elon Musk's Boring company I think his | used of modified Tesla's to transport people in the tunnels isn't | the best idea. | | The old streetcars, like in Detroit, used to attach to an | overhead wire to power themselves. I think you could have normal | train cars using this method. In other words use the electric | grid as opposed to batteries. I can't imagine a battery fire in | an enclosed area like a tunnel. | | Much better than NYC's subway using a live third rail which I | believe has killed more people falling on to the tracks than the | trains themselves. | mikeyouse wrote: | These are super common - all of SFs MUNI system is built using | the overhead wires -- batteries in the individual cars are | interesting because there's a ton of cost involved in | electrifying the entire length of the tunnel to deliver as much | power as a train needs. All of the substations, the physical | electrical cables themselves, etc add a ton of cost to | tunneling projects and long-term wear items that will require | endless maintenance that often shuts down the lines. | | Building a dumb cheap concrete tunnel and leaving the expensive | parts in the cars themselves could be a very cost effective | method of urban transport. Though I think the "use Teslas" is a | dumb addition since a purpose built train car similar to the | airport shuttles at Denver would be much more efficient and | handicap accessible. | tshaddox wrote: | To clarify, the light rail (Muni Metro) and electrified bus | lines use overhead 600 volt DC, but most of the bus lines are | not electrified. | nottorp wrote: | > I think you could have normal train cars using this method. | In other words use the electric grid as opposed to batteries. | | Like... most trains in Europe? | TheLoafOfBread wrote: | Subway makes perfect sense, except when you are CEO of a car | company. Then they are your direct competitor and suboptimal | solution of Tesla's in the tunnel is used instead. | WaitWaitWha wrote: | Electric trolleybus have been running in some cities pre-WWII | [0]. | | I have seen them in Budapest, Sao Paulo, and Malatya. | | [0]: https://en.wikipedia.org/wiki/Trolleybus | bilsbie wrote: | Thinking outside the box a bit I think there could be lots of | applications for "long extension cords". Especially when you | consider how light and thin a cord could be when you use high | voltage. | bloak wrote: | I agree. What someone needs to invent is a good way of powering | a tractor (or combine harvester) through an electric cable. | adamjc wrote: | I don't follow, how are high voltage cables able to be thinner | than low voltage cables? | mikeyouse wrote: | The limiting capacity of an extension cord is the resistance | it can carry - at high resistance the cord will basically | catch on fire. High voltage can deliver much more power at | lower resistance as compared to low voltage. The easy example | is household power -- in the US, standard household | electricity is 120v, so a common 14 gauge wire that can carry | 12A at constant load would be able to deliver 1400 watts. If | you use 240v, that same wire can deliver 2800 watts. | | To extend that to extension cords -- if your boat/tool or | whatever needs 5kw of power, at household voltage of 120v, | you'd need a #4 wire which weighs 1.3 lbs/10 ft. At 240V, | you'd need a #10 wire which weighs 0.3 lbs/10 ft. At 360v, | only a #14 wire which weighs 0.13 lbs/10 ft. | | So by tripling the voltage, you can cut down the weight of | the cable by roughly 10x. | Arrath wrote: | While annoying to route around trees and a bit of a hazard | considering the possibility of running the cord over, using a | corded electric lawn mower worked passably well for a small | yard. | jakear wrote: | Seems like ideal use case for a battery. Use 1/week max, rest | of time plugged in. I had one at my house and it was perfect | for my small-ish yard. | muti wrote: | This is an application where I find the old tech does a | better job: push mowers. | | I recently replaced my mower with an old push mower [1], | someone local restores them and sells them for a reasonable | price (much less than anything new or even a petrol or | electric second hand mower. | | It works so well I wouldn't go back unless I had more than | about 200 sqm to mow. Modern push mowers are junk and put me | off in the past, but the older ones are much heavier and | better built. They cut grass cleaner than a rotary mower | which is supposedly better for the grass too. | | [1]: trademe.tmcdn.co.nz/photoserver/full/1857940265.jpg | jimjimjim wrote: | yep, they are very light and maneuverable and not have a | battery pack allows for more interesting designs. but I have | run over the cord before. things went quiet for some reason. | unwind wrote: | There are rather big excavators/shovels as used in mining | operations, for large-volume material handling, that are | powered by a tether. I guess they don't nimble around much but | rather stay in roughly the same spot, filling trucks to haul | the rocks away for smelting/processing. | algo_trader wrote: | Do you have any experience with this ? | | Is it possible to have a 10KV x 100A power tether snaking | around like this ? | | There is a whole basket of safety requirements which kick in | with higher power scenarios | MisterTea wrote: | They do this with large mining machinery such as the drag | lines and bucket wheel wheel excavators. They don't move very | far so extension cords are acceptable. | | And in mining they run portable medium voltage wiring through | the tunnels to baby substations. They even make plugs and | sockets rated to 15kV or possibly to 35kV, the upper limit | for "medium voltage" in NA. | | Obviously you aren't going around plugging these cables in | like they're attached to a reading lamp. They are on | disconnects or circuit breakers and the circuit is de- | energized before connection or disconnection. Otherwise | arcing would destroy the connector. A faulted circuit would | cause an explosion on connection likely killing or severely | injuring an operator. | | Electricians working on medium voltage circuits must have | medium voltage training and certifications. ___________________________________________________________________ (page generated 2022-11-16 23:00 UTC)