Group: alt.2eggs.sausage.beans.tomatoes.2toast.largetea.cheerslove · Group Profile
Author: Larry GreenLarry Green Date: Aug 22, 2008 17:54
Humbug wrote:
> On Sat, 16 Aug 2008 07:39:49 -0700, muddy cat gmail.com>
> wrote:
> >> In article <332da49n1aujppddvab0neb5ltq5ap392d@ 4ax.com>,
>> Richard Sherratt NOTHINGHEREbrunsley.com.au> wrote:
>>>>> Three phase voltage in a 230-240 volt system is actually around 400
>>> volts. One of the times we lived in Germany (Bielefed, I think), the
>>> oven had a three-phase 400 volt supply. Thre square root of 3 is
>>> involved.
>> One of our standards in the US it's 480 VAC phase to phase and 277 VAC
>> phase to ground or neutral if one is required
>
>> (ground and neutral are not the same thing).
>
> Exactly so.
>
>> Lower voltages are derived from a transformer and the standard is 208
>> VAC phase to phase and 120 VAC phase to neutral. This is not the same as
>> household power.
>
> Does that mean all household supplies are coupled with a transformer?
>
Yes
> That sounds terribly inefficient.
Yes ;-)
Up here in the Great White North the power runs on poles beside the street and
where the power needs to be split off to feed a house they install a large, oil
filled, transformer to drop the power. The also have large open switches
(similar to all the open blade switches you used to see in the 50's horror
movies) mounted on the poles that can be thrown to switch off circuits.
The system is not particularly efficient and has problems. The power is prone to
flicking on and off around here in high winds and thunderstorms as the cables
swing in the wind and touch one another. They also have a habit of dropping
power if a pole gets hit by a car! In winter you can hear the transformers
buzzing and crackling if it is damp and misty or they are coated in ice.
The transformers also give off a tremendous fireworks display if they get struck
by lightening! I remember standing at the bedroom window during one storm and
a bolt of lightning hit a power pole in the parking area to our apartment
building. There was a brilliant white flash followed immediately by a large
blue/green fireball full of red/orange sparks then there was a double boom, one
from the thunder and the other from the exploding transformer! It was
spectacular to say the least!
--
Larry the Limey
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