IR cameras are a very useful feature to detect connections that
are getting hot, due to contact resistance increase.
Almost all the source of HF RFI is sparking noise caused by current
"arcing" over between one of the conductors and ground. This
usually only happens with the medium (15-48kV) voltage distribution
lines and the even high voltage lines (> 55kV).
The arcing doesn't produce any significant heating, and hence won't
register on an IR camera. It does produce ultrasonic noise, which
can be detected very close to the source.
73, de -KR- N6RCE
n6rce@arrl.net
-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On Behalf
Of Mike@RFI Services
Sent: Thursday, March 10, 2005 5:19 PM
To: 'Jim P'; richard@karlquist.com; rfi@contesting.com
Subject: Re: [RFI] PG&E IR line fault detection advertisements
I think the power co employee that said that about transformers was
possible a little unhappy.
IR is used by power companies to detect poor current carrying
connections as well as detection of insulators that are breaking down.
They are frequently responsible for early detection of major problems
and avoiding catastrophic failures in transmission & distribution
systems.
As for RFI, it isn't a good tool for locating or detection of the
source. However, the hotspots they detect are sometimes found to be RFI
sources. Rarely is the cause of an RFI complaint located by using IR.
This doesn't mean never.
I have, several times, worked with IR equipment vendors and tested the
usefulness of IR to locate RFI sources. Typically what we do is go
through a neighborhood and make a list of all the IR detected spots.
Then we locate all the RFI sources. Rarely are they the same. Not even 1
in 10 matches.
This isn't done in a lab with "high dollar equipment", but in the field
on actual sources.
If our test matched at least 75% of the time I would own IR equipment
for use in detecting RFI sources. Don't get me wrong, IR is great and is
a tool no power company should or can do without. It just isn't a useful
tool for RFI. It would be great to ride down the road and see the
hotspots and solve the RFI problems. It just isn't happening.
Have a great week end,
Michael C Martin
RFI Services
6469 Old Solomons Island Rd
Tracy's Landing MD 20779
240-508-3760 Tel
410-741-5153 Fax
mike@rfiservices.com
www.rfiservices.com
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