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If we could magically pick a frequency and voltage for electrical systems to use (without sunk costs), what would it be? What's the most efficient for modern g
by freeqaz 2y ago
If we could magically pick a frequency and voltage for electrical systems to use (without sunk costs), what would it be?
What's the most efficient for modern grids and electronics?
Would it be a higher frequency (1000hz)?
I know higher voltage systems are more dangerous but make it easier to transmit more power (toaster ovens in the EU are better because of 240v). I'm curious if we would pick a different voltage too and just have better/safer outlets.
- IncreasePosts 2y agoI don't care what the frequency is, I just want my LEDs to not flicker!
- sxp 2y agoNormal LED lightbulbs shouldn't flicker on standard 60Hz circuits. Do you have a dimmer switch or smart switch in the circuit? I've noticed these cause flickering that's visible on camera or out of the side of my eyes.
- xanderlewis 2y agoWhat about if they flickered at 10^-15Hz?
- viraptor 2y agoThat would be really annoying to tell if they're broken, or just currently in the "off" phase :)
- xanderlewis 2y agoAssuming they started on, you’d be lucky if they lasted long enough to ever reach their off state (~32 million years later).
- SSLy 2y agothat means that either the breaker is faulty, or the power stabilizator in the lamp itself is junk.
- lnsru 2y agoGet better ones. I installed expensive LED lamps at home and they’re fine. The guys in the office picked the cheapest ones and I don’t want to turn these ugly things on. Edit: Paulmann Velora are the expensive lamps at home.
- homebrewer 2y agohttps://lamptest.ru https://lamptest.ru tests for flicker too. I don't know if those models are sold in the US, though. Philips, Osram and IKEA should be.
- xanderlewis 2y agoWhy are toasters better at 240V? Can’t you just pull more current if you’re only at 120V (or whatever it is in the US) and get the same power? I guess there’s some internal resistance or something, but…
- mypgovroom 2y agoYou have a 240v toaster?
- xanderlewis 2y agoWell, closer to 230.
- qayxc 2y agogoes to check real quick between 238V and 245V at my outlets.
- stuaxo 2y agoLiving in an a country with 240v mains, yep.
- bbatha 2y agoMore current needs thicker wires. The average US outlet is wired for 120v15amp. 20 amp circuits are somewhat common, though 20amp receptacles are not. Certainly not enough for commodity appliances to rely on. Going to more than 20amp requires a multiphase circuit which are much more expensive and the plugs are unwieldy and not designed to be plugged and unplugged frequently.
- quickthrowman 2y ago> Going to more than 20amp requires a multiphase circuit There is no multi-phase power available in the vast majority of US houses. A typical residence has a 120/240 split-phase service, which is single-phase only. A service drop is two hot conductors from two of the three transformer phases and a center-tapped (between the two hot legs) neutral conductor. Either hot leg is 120v to ground and line to line is 240V. > https://en.m.wikipedia.org/wiki/Split-phase_electric_power https://en.m.wikipedia.org/wiki/Split-phase_electric_power Single-phase breakers are also available in sizes larger than 20A, usually all the way up to 125A.
- DrBenCarson 2y agoThe higher the voltage the less power lost to resistance and the less money spent on copper Short protection at the breaker for every circuit would probably be necessary at that voltage
- UltraSane 2y agoThe skin effect causes AC current density J in a conductor decreases exponentially from its value at the surface J_S according to the depth d from the surface. The depth decreases as the square root of frequency. This means that the effective power a wire can carry decreases with increasing AC frequency. https://en.wikipedia.org/wiki/Skin_effect#Formula https://en.wikipedia.org/wiki/Skin_effect#Formula
- Zardoz84 2y agoat same time, high frequency makes high voltage secure (or more secure) I receive 15KV discharges at high frequency and I live to write about it.
- redox99 2y agoYou could push it to 100hz, MAYBE 200hz at most. Higher than that, transmission losses due to skin effect would make it a bad idea. Also generator motors would require too high RPM. 240v is a good middle ground for safety and power.
- anticensor 2y agoFor 1kHz, you'd run the generators at the same speeds you run them for 50Hz but with 20 times as many poles.
- andrewla 2y agoImpulse Labs has built an induction range that has super high power; their trick is that they have a battery that they recharge from the mains. Might be expensive but the same technique could work for a toaster (or for a water kettle) to basically keep a whole bunch of energy in reserve and deliver it when needed.
- marssaxman 2y agoThat's a great idea - I wonder if electric kettles would be more popular in the US if they worked as quickly as they do on 240V? How large a volume of battery would one need to accomplish this, I wonder?
- duskwuff 2y agoI'm not sure it'd be commercially viable. A stove is a major home appliance, and the Impulse Labs unit is a high-end one with a price tag of $6000. An electric kettle, on the other hand, is considered a near-disposable piece of home electronics with a price closer to $50; it'd be hard to build a substantial battery into one at an affordable price.
- xyzzyz 2y agoIt would cost less than $50 to equip a kettle with appropriately sized battery. You only need something like 0.2 kWh of capacity.
- bobthepanda 2y agoElectric kettles mostly aren’t popular because of a perceived lack of need. Most Americans don’t drink tea and most coffeemakers heat water themselves. For most other applications using a pot on a stove is not a deal breaker.
- Borealid 2y agoI wouldn't want a kettle that wears out after only 3-10 years of use.
- buildsjets 2y agoAircraft AC electrical systems are 115V 400Hz, allegedly to minimize component weight.
- throw0101c 2y ago> Induction motors turn at a speed proportional to frequency, so a high frequency power supply allows more power to be obtained for the same motor volume and mass. Transformers and motors for 400 Hz are much smaller and lighter than at 50 or 60 Hz, which is an advantage in aircraft (and ships). Transformers can be made smaller because the magnetic core can be much smaller for the same power level. Thus, a United States military standard MIL-STD-704 exists for aircraft use of 400 Hz power. > So why not use 400 Hz everywhere? Such high frequencies cannot be economically transmitted long distances, since the increased frequency greatly increases series impedance due to the inductance of transmission lines, making power transmission difficult. Consequently, 400 Hz power systems are usually confined to a building or vehicle. * https://aviation.stackexchange.com/questions/36381/why-do-aircraft-use-400-hz-ac-instead-of-the-50-or-60-hz-of-wall-outlets https://aviation.stackexchange.com/questions/36381/why-do-ai...
- kristianp 2y agoDo electric car motors make use of this property too? I know some cars, such as Porches use higher voltage to enable faster charging.
- freeqaz 2y agoInteresting to think about what the future could look like. What if breaker boxes were "smart" and able to negotiate higher voltages like USB-C does? It would avoid the problem of a kid sticking a fork in an outlet, or a stray wire getting brushed accidentally when installing a light fixture. Time will tell!
- duskwuff 2y ago> What if breaker boxes were "smart" and able to negotiate higher voltages like USB-C does? That'd be difficult; a breaker typically feeds an entire room, not a single outlet. (And when it does feed a single outlet, that's typically because it's dedicated to a specific large appliance, like an air conditioner or electric stove, which wouldn't benefit from being able to dynamically negotiate a voltage.)
- ianburrell 2y agoAppliances, like electric range, that need higher power have dedicated 240V circuits. My understanding is that 240V circuits use thicker cable because they usually also have higher current. But it is possible to convert 120V to 240V if only one device, sometimes done for imported electric kettles.
- pgalvin 2y ago> It would avoid the problem of a kid sticking a fork in an outlet One of the best things about living in the UK! https://www.youtube.com/watch?v=UEfP1OKKz_Q https://www.youtube.com/watch?v=UEfP1OKKz_Q
- burnerthrow008 2y ago> If we could magically pick a frequency and voltage for electrical systems to use (without sunk costs), what would it be? > What's the most efficient for modern grids and electronics? I do not think it is possible to answer the question as posed. It is a trade-off. Higher frequencies permit smaller transformers in distribution equipment and smaller filtering capacitors at point of use. On the other hand, the skin effect increases transmission losses at higher frequencies. If you want minimum losses in the transmission network, especially a very long distance transmission network, then low frequencies are better. If you want to minimize the size and cost of transformers, higher frequencies might be better. Maybe the generator is close to the user so transmission loss is less important. If you want smaller end-user devices, high frequency or DC might be more desirable. You have to define some kind of objective function before the question becomes answerable.
- im3w1l 2y agoWouldn't it make sense to do both then? Low frequency or even dc long distance transmission that gets converted to standard frequency closer to the user?
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- connicpu 2y agoThere's considerable losses involved when you want to convert between frequencies. DC also has considerable losses over long distance, so there's a lower bound on the frequency before the efficiency starts to go down again.
- manwe150 2y agoRight, with modern technology my understanding is HVDC (essentially 0HZ?) is the way to go now (high voltage to minimize resistive loss, DC to minimize skin effect) if we were building a new grid with the same wires, but not economical to retrofit an existing system that is already working, since it is already working
- Workaccount2 2y agoHigher Voltage: Less conductor material needed, smaller wires. But need more spacing inside electronics to prevent arcing, and it becomes more zappy to humans. Also becomes harder to work with over 1kV as silicon kind of hits a limit around there. Higher Frequency: Things that use electricity can be made smaller. But losses in long transmission become much worse. DC instead of AC: Lower losses in transmission, don't need as much spacing inside electronics for arcing. But harder and less efficient to convert to different voltages.
- Max-q 2y agoToday, with swichmode supplies, I think DC would make most sense. We lose much power to frequency deviation and inductive loads causing phase shift. It would also make sense to have a high voltage and low voltage nets in houses. Low voltage for lighting and other low power equipment. High voltage for power hungry equipment. For example 48V and 480V.
- Dylan16807 2y agoDo we really lose much to phase shift? Increasing apparent load only causes a tiny fraction of that much waste, and local compensation isn't very expensive. DC or a significant frequency boost would be good inside a house for lights and electronic items. Not so great for distribution. I'm not convinced multiple voltages would be a net benefit outside of the dedicated runs we already do for big appliances.
- frrlpp 2y agoDC high voltage (200v) is very dangerous and pernicious, and mores difficult to switch on and off because of arcs.
- flyinghamster 2y agoVery old US light switches often had both AC and DC current ratings, and the DC rating was noticeably lower due to the arcing problem, even with fast-acting snap action. My grandfather worked in a Chicago office building that had 110V DC service even into the 1960s. He had to be careful to buy fans, radios, etc. that could run on DC.
- stephen_g 2y agoYes, it’s more dangerous, but technically “high voltage” doesn’t start until 1500 V DC (and 1000 V RMS for AC) by most standards (e.g. IEC 60038)
- xxs 2y ago>Would it be a higher frequency (1000hz)? Totally not, that would mean both worse skin effect and worse impedance. Likely the best option (if you really don't care about the existing infrastructure) would be DC, 0Hz. There are some downsides of DC, of course.
- gosub100 2y agoThis would be excellent for solar because it removes the efficiency loss from the inverters. AFAIK it's very hard to add/remove loads without spiking power to everything else on the line. A friend of mine applied for a job at a company that was trying to run DC in the home but it's not a trivial endeavor.
- jorvi 2y agoIs there even a use to running DC in a home? Almost everything complex does run on DC internally, but you feed those via AC adapters that then invert it to DC. You'd have to get bespoke DC-DC adapters (transformers, really) for everything.
- xxs 2y agoAC-DC are effectively -> AC + power correction boost to even higher AC, then high voltage DC, the AC (high freq), then transformer, then low volt DC + feedback to the primary DC ; {then DC->DC (potentially)} DC (high) voltage to DC would skip the 1st few steps of AC->DC.
- jorvi 2y agoThat is very interesting to know, thank you! I always assumed it was just one induction and transformation step.
- gosub100 2y agoIs there even a use to running DC in a home? Lights, first and foremost. LEDs are DC. > Almost everything complex does run on DC internally almost everything runs on either 5V or 12VDC. What you would need are appliances that bypass the wall-warts/adapters and tap directly off DC, but this comes with some significant challenges. I'm already talking way outside my wheelhouse though, so I'll stop before I make a mockery of this topic.
- pwrson 2y agoProbably about the same as we have. Higher frequencies have terrible transmission (skin effect, transmission line length limit) and would start to interfere with radio. Lower frequencies need larger transformers. DC while nice is too expensive. So about where we are now.
- dreamcompiler 2y agoDC. Modern electronics make AC grids unnecessary. 48VDC inside homes would be enough for most applications except heating and it would be kid-safe. 240V for heating applications.
- 1970-01-01 2y agoWithout sunk costs, objectively it's 000Hz. Voltage is mostly irrelevant too. https://en.wikipedia.org/wiki/High-voltage_direct_current https://en.wikipedia.org/wiki/High-voltage_direct_current