30 Jan
2011
30 Jan
'11
8:05 p.m.
Hi,
On 31/01/2011, Brian Lanning <brianlanning at gmail.com> wrote:
In the US, two separate 110 legs are delivered to the
house. When we
need 220, the magic of constructive interference is applied, and we
get 220. The 220 is delivered to the appliance as two separate 110
wires, a neutral wire, and sometimes a separate ground wire for
safety.
This doesn't look quite right to me, but it is probably close enough
for most applications.
Because of this arrangement, sometimes appliances (I
believe, maybe
I'm wrong) will pull 110 from one of the legs to power electronics in
the appliance.
But I think european 220 doesn't work this way. Is one 220 leg
delivered to the house? And the electronics work off that 220 leg?
Or are two 110 lines delivered and every outlet gets the sum of those
two 110 lines?
In Europe, a typical property is supplied with a single 230V RMS AC
single phase and neutral supply. If you pay enough money and/or are
small industrial etc, you can get a three phase and neutral supply.
Each phase is 230V RMS AC phase to neutral, 400V RMS AC phase to
phase.
The only way to get 110V RMS AC is through a stepdown transformer.
If it's not two separate legs, I'm thinking
that it will be impossible
to wire an american 220 appliance to work with european 220. Is this
right?
I don't know enough about american 220V applicances.
Many switch mode power supplies will work happliy with both 230V and
110V. The 110/230 switch only ever seemed to switch in a secondary
capacitor after the bridge rectifier for the HV DC supply to the
switching circuitry. I guess it was difficult to get 300VDC+
capacitors for a while. Adding a second capacitor (in series) meant
that each capacitor only ever saw about 1/2 the DC voltage, and hence
kept the smoke in.
Simon
--
------------------------------------------------------------------------
"Well, an engineer is not concerned with the truth; that is left to
philosophers and theologians: the prime concern of an engineer is
the utility of the final product."
Lectures on the Electrical Properties of Materials, L.Solymar, D.Walsh