[HN Gopher] Hybrid AC/DC distribution system with a shared neutr...
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Hybrid AC/DC distribution system with a shared neutral (2020)
Author : 1970-01-01
Score : 19 points
Date : 2025-05-01 00:30 UTC (22 hours ago)
(HTM) web link (electrical-engineering-portal.com)
(TXT) w3m dump (electrical-engineering-portal.com)
| deepsun wrote:
| So we're saving on the wire only. I would probably pay for extra
| wire just to make the system simpler, unless I was a builder
| aiming to save on costs.
| Gibbon1 wrote:
| What the world needs is a 150 watt low voltage power over
| ethernet standard for lighting an low power appliances.
| londons_explore wrote:
| USB-C fulfils that already.
|
| It doesn't work out economically because big networks of usb
| devices (ie. Hubs) _all_ need the power components if one is
| to maintain the generalisability of being able to plug
| anything into the grid anywhere.
| kevin_thibedeau wrote:
| USB has significant length limitations and the cabling is
| generally not plenum rated. It's also silly to have a cable
| with wires that will never be used beyond negotiating for
| power.
| deepsun wrote:
| USB-C is for short distances (<4m) and is more expensive
| than CAT6 cable.
|
| https://www.cablematters.com/Blog/USB-C/how-long-can-a-
| usb-c...
| holowoodman wrote:
| There is, shockingly enough, 100W PoE lighting...
|
| https://www.cisco.com/c/en/us/solutions/enterprise-
| networks/...
|
| Imho a totally crazy waste of expensive gear, but whatever
| floats your boat...
| SigmundA wrote:
| POE+++ is 90W so maybe POE++++?
|
| Hard to go up in voltage as its now no longer considered
| "low" voltage wiring and hard to go up in current without
| increasing conductor size of ethernet cable.
| allenrb wrote:
| POE+=4 is a clear win at this level. ;-)
| bill3478 wrote:
| Wouldn't that be POE+=2?
|
| Also, if this is anything like USB it will be PoE 3.14
| Gen 2 type E.
| kbaker wrote:
| I could hope for a future PoE-over-Data Line (PoDL) version
| using an 18 AWG twisted pair that would work for this,
| providing something like 48V @ 3 or 4 A, and 10BASE-T1L for
| data. Hopefully a standard way to do this gains traction.
|
| The existing limitation is with the 2x23 AWG (or 4x23 AWG) of
| Cat5e/6/6a not providing a lot of current-carrying capability
| at a safe voltage.
| deepsun wrote:
| Was just thinking about it for my home. Googling showed that
| it's only for commercial applications now (like "request a
| quote" for a lightbulb).
|
| There is a good opportunity for a startup IMHO.
|
| With 100W PoE, one can daisy-chain 10 light bulbs on one
| cable (or put them on different pairs of wires within one
| cat6 cable).
|
| But what I really wanted is controllable devices, so that I
| could re-assign lights<->switches in my home hub.
|
| UPDATE: and you don't need an electrician license to work
| with low voltage.
| somat wrote:
| A managed switch will allow you to power on/off specific
| ports.
|
| When I was looking at home automation systems and all the
| insanity found there. at one point I said "if I were to
| design a home automation system from scratch what would it
| look like?" my answer for the physical layer was poe and
| managed switches.
| zdragnar wrote:
| As an American, I'd just be happy if we switched to 240v
| rather than 120.
| SigmundA wrote:
| Not sure sharing the neutral buys much as conductor size needs to
| go up vs just running separate wire.
|
| Most hybrid inverters now days are high frequency and have a HVDC
| bus sitting between battery DC/DC, solar MPPT and AC
| inverter/converter. Since solar comes down from roof with HVDC it
| can be inverted without a transformer to AC then the LV battery
| uses a physically smaller HF transformer on the buck/boost to
| that bus.
|
| Seems to be lots of talk to tap that HVDC bus for say EV charging
| as its around 400v, also some inverters moving to HVDC batteries
| as well simplifying the DC/DC even more so.
|
| Could see a future where houses have a HVDC panel with battery,
| solar, inverter and EV charger hanging off it, perhaps even HVDC
| from pole with solid state transformers. If/when EV become
| popular then you will have much more readily available/cheap HVDC
| switching gear at 400/800v. Hard to beat the simplicity and
| reliability of AC using transformers though for distribution.
| MisterTea wrote:
| > Not sure sharing the neutral buys much as conductor size
| needs to go up vs just running separate wire.
|
| The article mentions a system which will balance the shared
| current. But that sounds like needless complexity that was
| introduced to entice power companies by saving a few bucks not
| needing two insulators and conductors installed on each pole.
| bill3478 wrote:
| Really not sure what/who this is for. There aren't many 3-phase
| LV AC + DC use cases apart from industrial load + control. I
| can't imaging the DC part can be transmitted at a voltage that
| will make the system efficient while avoiding an expensive step-
| down conveter.
| analog31 wrote:
| Amusingly, the first thing I thought of was "phantom power" for
| microphones, where a power supply for the microphone is carried
| along the same pair that returns the audio signal.
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(page generated 2025-05-01 23:01 UTC)