3 ms·
> though cables that can carry megawatts of energy Not really, high speed train lines do it all the time. They usually operate at 25 kV or 50 kV and often cons
by dheera 4y ago
> though cables that can carry megawatts of energy
Not really, high speed train lines do it all the time. They usually operate at 25 kV or 50 kV and often consume a few megawatts per train.
(At 50 kV, one megawatt is only 20 amps, which you can deliver on 12 AWG wire, theoretically.)
- titzer 4y agoUh no, do not put 50,000 volts through 12 AWG wire.
- jefftk 4y agoWhat goes wrong?
- WJW 4y agoMost store-bought wires won't have sufficient covering to prevent arcing, so you might get a short circuit somewhere. If you insulate the wires sufficiently however, any wire will take almost any voltage. It's the current you should worry about, as other commenters have already mentioned.
- cesaref 4y agoAs has been stated, voltage isn't a limitation, its the current that. Go and look at the HT wiring used in a cathode ray tube display, and you'll see it's a lot less that 12 AWG, and happily carries 10-20kV.
- the_third_wave 4y agoWhen I went to high school the teacher told about a science fair where someone had put a sign next to his project reading: WARNING 2 million Ohms (or something like that, I don't remember the actual number of Ohms for this specific project) A remarkable number of people kept their distance from this obviously dangerous experiment. The chemistry-equivalent of this joke is to warn everyone around you of the presence of dangerous di-Hydrogen Oxide which kills hundreds of thousands of people every year.
- rascul 4y ago> The chemistry-equivalent of this joke is to warn everyone around you of the presence of dangerous di-Hydrogen Oxide which kills hundreds of thousands of people every year. https://dhmo.org/facts.html https://dhmo.org/facts.html
- comboy 4y agoIn their defense, maybe those people didn't know if it's a project by a very clever student or by the one who mixes up units ;)
- elliottkember 4y ago2 million ohms? Not bad, not terrible. Vasily, get the good Ohmmeter from the safe.
- quickthrowman 4y agoWhy not? You obviously wouldn’t do it to a THHN conductor that is rated for 600v, but there are certainly #12 AWG conductors rated for higher voltages. They have a whole lot more insulation/layers than a regular 600v rated conductor, see: https://www.powerandcables.com/wp-content/uploads/2019/10/Figure-2.jpg https://www.powerandcables.com/wp-content/uploads/2019/10/Fi... High voltage utility distribution lines aren’t insulated by anything other than porcelain bushings and air.
- gooseyman 4y agoCame here to say this. Romex/THHN might be a bad idea, but that's because they weren't insulated for this purpose. 12 AWG would work.
- josephcsible 4y agoThe term "12 AWG" only specifies conductor thickness. Voltage is limited by insulation and current is limited by conductor thickness. Assuming sufficient insulation, it's safe to run arbitrarily high voltages through any conductor, since it doesn't even "see" the voltage.
- deleted 4y ago[deleted]
- spinningslate 4y agoyes, but: 1. You need a _lot_ of insulation at 50kV 2. I'm no expert but I very much doubt you could run a motor at anything approaching that voltage. Current electric cars, for example, run c400V as the main motor supply. So there would need to be voltage conversion, which adds weight and bulk.
- quickthrowman 4y agoI know for certain there are 13.8 kV motors, I don’t see any reason why higher voltages aren’t possible for motors.
- bobthepanda 4y agoUsually you need to transform power anyways on a train, because * lights, plug sockets, etc. are all at normal household voltages * often trains will run on multiple voltages, so a transformer needs to be involved anyways * lower voltages let you have thinner insulation, so thinner wires let you save space for things that matter more like a bigger passenger cabin
- tomek_ycomb 4y agoThere already is conversion. The motors are inductors and phase current can be much higher than battery current
- kwhitefoot 4y agoQuite a few of the newer EVs have 800 V batteries to make fast charging more practical with cables light enough to be handled by ordinary humans. You can make an electric motor run on pretty much any combination of voltage and current. You just have to make the appropriate trade-offs in insulation, conductor cross section, etc. ABB (my former employer) makes motors that run on 13.8 kV with a power of up to 29 MW. See https://new.abb.com/motors-generators/high-voltage-induction-motors/modular-induction-motors https://new.abb.com/motors-generators/high-voltage-induction...