The BPL modeling I have done couples energy onto the power lines in the same
fashion as a sparking insulator. In this case, it appears that the horizontal
wiring and the vertical ground wires both contribute to the emissions.
There is also a vertical component caused by the E field gradient at the wire
vs the lower E field present near the ground.
Ed Hare, W1RFI
ARRL Laboratory Manager
225 Main St
Newington, CT 06013
Member: ASC C63 EMC Committee
Chairman: Subcommittee 5, Immunity
Chairman: Ad hoc BPL Working Group
Member: IEEE SCC-28 RF Safety
Member: Society of Automotive Engineers EMC/EMR Committee
> -----Original Message-----
> From: firstname.lastname@example.org [mailto:email@example.com]On
> Behalf Of Jim Brown
> Sent: Monday, July 19, 2004 9:39 AM
> To: firstname.lastname@example.org
> Subject: RE: [RFI] Power Line Noise in Indonesia
> On Mon, 19 Jul 2004 12:43:08 -0000, David Robbins K1TTT wrote:
> >Since you say that the noise is better when it rains there are two
> >possible explanations. First, the insulator surfaces are cracked or
> >have arc damage, in this case the rain is filling the gaps
> and causing
> >steady current instead of arcing. These should be replaced. The
> >is that the insulators are dirty. In this case the arcing is between
> >gaps in the contamination, when it rains the gaps are bridged or the
> >contamination is washed off for a while, once the surface dries the
> >noise starts again. Power washing can remove contamination
> >shutting off the line, but must be repeated regularly if you are in a
> >marine or heavy industrial area that contaminates them quickly. I
> >also seen some surface treatments that can help prevent surface
> >contamination, but not sure how widely these are available.
> While we're on this general topic -- one of my pro audio engineering
> friends has pointed out corona discharge as a chronic problem in
> coastal areas. Can someone address the mechanics of this problem
> and arcing at insulators in general?
> I am of the opinion that it is the vertical downlead (running
> down the
> pole to earth) from protection devices that does most of the
> of noise that is coupled from protection devices to this
> "ground" lead.
> Based on the height of a typical pole, this downlead is going to be a
> most efficient as an antenna between roughly 5 MHz and 10 MHz.
> Thoughts anyone?
> Jim Brown K9YC
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