On Fri, 17 Jul 2009 20:42:30 +1200, Miche >
shouted from the highest rooftop:

>In article >,
> bob in nz > wrote:
>
>> On Thu, 16 Jul 2009 21:54:20 -0500, "Pete C." >
>> shouted from the highest rooftop:
>> >
>> >bob in nz wrote:
>>
>> <snip>
>>
>> >> We have what's called 3-phase power and no-one can explain it to me.
>> >
>> >Nothing magic about three phase power.
>> >
>> >Your ordinary table lamp as an example plugs into a 120V single phase
>> >circuit, there are two wires, one "hot" which is the 120V AC source and
>> >one "neutral" which is the return to complete the circuit. With three
>> >phase power there are three separate "hot" lines that come into the
>> >building along with one common "neutral".
>> >
>> >The reason you sometimes loose power to parts of the house is that
>> >outside of three phase motors, virtually everything you have in the
>> >house runs on single phase power and is hooked up to one of the three
>> >"hot" lines coming into the house. A falling tree in a storm can land on
>> >and break or short out just one or two of the three lines on the
>> >distribution poles, so you may still have some powered. Outside of three
>> >phase motors, there isn't much that actually uses three phase power in
>> >it's entirety.
>> >
>> >In the US we use single phase power for homes and three phase power for
>> >commercial and industrial buildings. With single phase power, even
>> >though all primary utility power distribution is three phase, the single
>> >phase low voltage feeders that feed a house are fed by transformers that
>> >only receive power from one of the three primary lines on the pole, so a
>> >tree taking out one of the primary lines will either take out all of
>> >your power or none of it.
>> >
>> >This is a very simplistic explanation, so no flack from those of you who
>> >know the details, I know them too.
>>
>> Many thanks for that. Even I can understand it now. Turns out that one
>> of our neighbour's trees had shorted out one of the lines but not the
>> others.
>>
>> BTW - we run on 240v in New Zealand.
>
>230V, 50Hz.
>
>3-phase is 400V.

Shows what I know ;-)b


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una cerveza mas por favor ...

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