Anyone with Roger's Lite accounts?

[James Knott]

Lennart Sorensen wrote:
> On Mon, Apr 17, 2006 at 06:10:23AM -0400, James Knott wrote:
>> Broadband over power lines is a very bad idea.  It tends to cause a lot
>> of interference to licenced radio services.  The broadband service uses
>> the same spectrum as many radio services and since the power lines
>> weren't designed to carry those frequencies, they act like antennas.
>>
>> There are a couple of battles going on in the U.S. about this right now.
> 
> What if they only do it where the power lines are underground?

There's still potential leakage within the building.
> 
> There seems to be a number of places in europe using it without major
> complaints about radio interference.  There also doesn't seem to be many
> places left in europe with above ground power wires.  They also have the
> advantage there, that by running double the voltage, the need a lot less
> transformers around (although they are bigger), since you can run a lot
> further from the transformer before the voltage drop is significant.
> This makes it much cheaper to install the network gear at the
> transformer for an area than it is here where we have a transformer
> every few hundred meters.

You don't appear to understand quite how our electrical system is
configured.  What we have here, is a 240V distribution network, with the
center point grounded.  This means that when the two sides are balanced
there is no current in the grounded "neutral" wire.  Even when they are
not perfectly balanced, only the difference current is carried by the
neutral wire. As a result of this, the transmission efficiencies are
comparable.  It also means that consumer level devices generally have
only 120V in them, which is far safer than 240V.  As far as I know, this
sort of system doesn't occur in Europe.  Also, European transformers
will be larger, due to the lower power line frequencies, which required
more iron than 60 Hz power.  Transform core size is determined by power
levels and frequency and not by voltage.


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