J
Jasen Betts
Guest
On 2019-06-28, Rick C <gnuarm.deletethisbit@gmail.com> wrote:
yes, theat's the whole point
> We don't distribute power at 240 volts.
I was trying to use Larkins terminilogy, he said 240V I know thats
really 120-0-120 and I treated it as such. the three phase used in UK
is 240 to neutral, 415 between phases, I called it 415 to follow the
convention established by Larkin, that's also what they write on the
transformers.
> As has been explained, we use a transformer for typically 1 to 4 homes.
Or a "whole block" aparrently, whatever that means.
The discussion started off being about how using higher voltage allows
thiner wires.
--
When I tried casting out nines I made a hash of it.
On Friday, June 28, 2019 at 3:01:06 AM UTC-4, Jasen Betts wrote:
On 2019-06-28, John Larkin <jjlarkin@highlandtechnology.com> wrote:
On Fri, 28 Jun 2019 05:22:49 -0000 (UTC), Jasen Betts
jasen@xnet.co.nz> wrote:
On 2019-06-27, John Larkin <jjlarkin@highland_snip_technology.com> wrote:
On Thu, 27 Jun 2019 17:31:20 +0300, upsidedown@downunder.com wrote:
On Thu, 27 Jun 2019 07:55:53 +0100, Tom Gardner
spamjunk@blueyonder.co.uk> wrote:
On 27/06/19 07:20, upsidedown@downunder.com wrote:
On Wed, 26 Jun 2019 23:42:43 -0400, bitrex <user@example.net> wrote:
On 6/26/19 10:09 PM, Rick C wrote:
On Wednesday, June 26, 2019 at 9:57:47 PM UTC-4, keith wright wrote:
On Wednesday, 26 June 2019 18:14:57 UTC-7, bitrex wrote:
...
"Charging at home will require
the installation of a dedicated high-capacity outlet"
a 40 amp level 2 charger unit is plenty for many use cases and
installing one is not a complex job. it won't charge up the car in a
couple hours. it'll charge a 3 up ~150 miles overnight, how many people
are driving 150 miles a day every day goddamn.
The summary seems to make it out like you can either charge from a 120
volt outlet over 1.5 days or you have to install a three phase AC-DC
level 3 charger with a cable 4" in diameter to charge the car.
...
'Which' is a UK magazine so a normal wall socket can do up to 2-3kW (as a reference other cars in the UK seem to be set to 10A resulting in 2.4kW).
I did forget that this was a UK magazine. I have talked about this with folks from there and I never got a clear answer, but it seems like they do 13 amp outlets easily, but to get more they wire 3 phase, which *is* a lot more hassle... at least I guess so. They talk about totally different wiring methods than we use and smaller service to the house, so maybe higher current 240 volt outlets aren't so easy. On the other hand, they tend to drive shorter distances so the daily need for charging is not as much. The 3 kW available from a standard outlet gets you around 180 miles on a model 3... assuming they don't do the derating thing that we do in the US. Can someone confirm that?
In the UK there are a number of smaller EVs available with smaller batteries and higher mileage. I don't know the names, but they seem to work well according to the owners.
I believe it's common in the UK and Europe to have smaller per-dwelling
or per apartment (flat?) structure distribution transformer/pole pig as
compared to the US where there's usually one large pole pig to supply a
neighborhood
It is the other way around. In Europe pole mounted transformers are
typically 100-315 kVA feeding dozens of detached houses up to several
hundred meters from the distribution transformer.
Here you /never/ see pole mounted transformers for
domestic properties.
So you have those low transformer buildings every few hundred meters
feeding the houses around it.
In Finland, you can get at least a 3x63 A 230/400 V up to 600 m from
the (ground or pole mounted) distribution transformer from most
electric companies.
In the US, due to lower voltage and hence large currents, a
distribution "pig" transformer only serves one or at most a few
houses.
That's silly. The size of a transfomer depends on KVAs, not voltage.
The size of the wire depends on voltage.
Current, actually.
For 115V you need wires 4 with
times cross section to get the same power loss as for and equivalent
power load at 240V (and it gets even better with three phase)
Makes no sense.
[...]
I didn't express myself very well.
what I meant was
The size of the wire depends on voltage. For 115V you need wires with
four times cross section to get the same power loss as for an equivalent
power load at 240V (and it gets even better with three phase)
So for 240V you can install fewer transformers and run longer drops (reducing maintenance
costs) and still come out ahead on energy loss and amount of copper used.
My house in the USA has 240 volt input from the
neighborhood distribution transformer. Houses in Europe also get 240
from their transformer. Both transformers step some kilovolts down to
240.
No, down to 415 3 phase wye in UK. (and here in NZ) they run that
along the street and tap off single phase feeds or three phase
feeds as required.
for example
at 415V three phase 1 MVA
the phase current is 1389 A
allowing a 10 kW loss (which is 1%) the cable can have a resistance of
1.73 milliohms
so that's 4 conductors of 478 S conductivity so 2314 S total. (IE
total conductivity of the 4 conductors in parallel)
at 240V "split" phase 1MVA
the phase current is 4167 A and the 1% loss occurs at only 0.288
millohms resistance, so that's three conductors of 3472 S so about
10416 S total conductivity.
looks about 4.5 times as much copper is needed to do the same job.
It looks to me like you are comparing apples and oranges. You are comparing 415 volt, 3 phase distribution in the UK to 240 volt, single phase distribution in the US.
yes, theat's the whole point
> We don't distribute power at 240 volts.
I was trying to use Larkins terminilogy, he said 240V I know thats
really 120-0-120 and I treated it as such. the three phase used in UK
is 240 to neutral, 415 between phases, I called it 415 to follow the
convention established by Larkin, that's also what they write on the
transformers.
> As has been explained, we use a transformer for typically 1 to 4 homes.
Or a "whole block" aparrently, whatever that means.
I expect if you compared the losses overall you would find they are
comparable. The US system has more, smaller transformers, the UK
system has fewer, larger transformers.
The discussion started off being about how using higher voltage allows
thiner wires.
--
When I tried casting out nines I made a hash of it.