[Lowfer] PLC?

[lowfer@mailman.qth.net]

At 02:12 PM 02/12/2004, Dexter McIntyre W4DEX wrote:
>Have I heard my first PLC?  If so it sounds flaky to me.
>
>Recorded between 1800 and 1830Z 12feb04 on 186 kHz with loop NW/SE:
>
>http://w4dex.com/temp/186khz12feb04.wav
Dex:
This "could be" PLC of the "trip blocking" genre...
(It is not Telemetering, and it is not "trip initiating" PLC,
and there is no intelligence conveyed, obviously)

Trip-blocking PLC is called "Relaying" by the power industry,
and consists of "single frequency" transmitters and receivers looking 
across each segment of a
path between major substations or generating plants to substations, etc.

It is silent until a major disturbance causes a "fault"on one section of the
path.  Then all transmitters "fire" at once to BLOCK tripping breakers.
The lone breakers that WILL trip are the ones that are on each side of the 
"fault"
as they will not hear each other due to that fault.

The rest of the "path" from generating plant to major cities or substations 
will
not be "tripped out" and will continue to get power "back fed" from other
sections of the grid.

NOW.... the question to be asked is.... did this signal occur during a 
storm that
might have been within 100 miles of you?    It seemed to be occurring a bit 
too often
but perhaps could have been keyed by an overly sensitive substation line 
relay.....

That's about as far as we can take this........ on the PLC idea, that 
is....   :-)

Perry    w8au           (FirstEnergyCorp/Telecomm/ret)