> > First, to get common names:
> > Hot = one Phase
> > Neutral = Protective Ground
> > Ground = Ground (the starpoint on 3 phases connected to earth at the
> 'generator')
> > Hot and Ground are the basic wires to tap power,
> Wrong... HOT and NEUTRAL provide the power legs. Earth Ground is only for
> protection and does not carry any power.
Ok, I just couldn't figure it out by myself (and no dictionary was able :),
but that's the reason why I put this definition table upfront - so just
read my not with switched names.
> The power company generates three phase because it is more efficient.
> However, in most residential areas they only provide a single phase. It
> doesn't make economic sense for them to string three wires when a single
> phase will suffice.
Shure it makes a lot of sense, since the balancing of the load will
be better _and_ of course the price of the wire wil be way lower
due higer voltage (400V/415V instead of 230V/240V) and inherent
caracteristicas of 3~ vs 2~ transmission (would take some pages to
describe).
Over here only 3~ power lines are supplied, no matter if comercial
or residential area or building - even in the most rural places 3~
is standard (for new installations).
> The single phase (high voltage) is fed into a simple center tapped
> transformer where it provides 240 VAC for high power appliances and
> 2-phases each with 120 VAC for lighting and general use.
Not 230V/115V ?
> In the early days, it was common for manufactures to use the device chassis
> or frame as a conductor. They would tie the Neutral wire to the chassis
> (under the assumption that the potential was near 0V) and save a few
> pennies in the manufacturing process. The problem was, it was possible to
> put the plug in the socket upside-down.
> Today, most devices have polarized plugs so that can't happen.
That's exactly what I tried to explane: plugs here in Germany are NOT
polarized (since the our system is no descender of an DC system, and
for an AC plus Protective Ground System it isn't needed to distinguish
the power lines, as long as the Protective Ground is defined)
> The neutral line should NEVER be fused. If that fuse happened to blow and
> the one on the HOT(s) leg didn't, the device would still be hot (even with
> a blown fuse). This would cause an unsafe condition.
a) true, if Neutral is true a grounded line - from your schematics it
isn't defined (unless you don't connect neutral via an anchor to 'True'
Ground - which must be tha same at the generator, whitch lead to the
conclusion that your 'highvoltage' lines are 2 phases of a 3~ system (*))
b) true as long as you look for fixed installed fuses within the fixed
household installation.
c) not true if it is about fuses within an electronic device (after the
power outlet/plug) - where 'Hot' and 'Neutral' is no longer defined -
at least when using systems that allow symetric interchange of the two
power lines (as used in most Europe). And AFAIR this kind of devices
are to be connected, and the fuse we are talking about are Fuses within
the devices.
(*) But if this is true, that these are 2 phases of a 3~ system
(and the Neutral is tied to 'True' Ground), then you only need
200V (208V) to get 115V (120V) on each coil of the transformer.
Gruss
Hans
Hey, Sallam, couldn't this power thing be a good addition for
VCF 3.0? A speach about how to operate Eq. from a different
country (and power system) in an acceptable and safe fashion ?
Maybe if Philip and me (possible with a thirs, US guy) team up
to give an outline of the different circumstances to remember
when using foreign (old) computers ? There might be some need.
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HRK
Received on Tue Apr 20 1999 - 13:17:21 BST