[RFI] RFI from HIGH voltage power lines

Fri Jun 1 10:31:17 PDT 2012

There are a wide range of voltages used for dc, see
http://en.wikipedia.org/wiki/List_of_HVDC_projects for a good list.  The
voltage used would depend on distance and how much power they need to
transmit.  The big advantage of dc for wind power would be not having to use
synchronous generators, this should make the wind end of the circuit easier
to control since they don't have to worry about controlling frequency, in
addition to the reduced losses and other dc advantages.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: Dale Svetanoff [mailto:svetanoff at earthlink.net] 
Sent: Friday, June 01, 2012 16:01
To: RFI Services' Michael Martin; Jim Miller KG0KP; RFI Reflector
Subject: Re: [RFI] RFI from HIGH voltage power lines


As always, good info and advice.  I do have a comment and a related

The comment: I don't know the situation in all parts of the country, but
here in Eastern Iowa, there might be two (2) power companies involved with
some power transmission poles.  A few years ago, I contacted my power
provider, Alliant Energy, about a nasty RFI problem (20 over S9 on 160m)
that I had traced to a pole about 1 mile from my house.  Alliant reacted
very quickly and I even got a call from the crew chief who told me that the
RFI by the pole was so bad, he could not hear the local AM station (WMT, 5
kW) on his radio in the truck.  I later got another call to tell me that the
problem was determined to not be an Alliant issue, but was actually the
responsibility of another company that owns the higher voltage transmission
lines further up the pole.  (Alliant's lines run at 12.5 kV, and these other
lines were running at 34.5 kV.)  Luckily, the Alliant crew chief explained
that I would not have to make another call to report the interference.

The other power company, ITC (as I recall), actually contacted me after my
S-meter went down to S-1 on 160m and told me that the problem had been a
broken wire that connected a lightning arrestor to ground.  The racket was
caused by arcing between the two ends across the break.  I was grateful to
both power companies, but I mention this instance as a "heads-up" to anyone
who may end up dealing with more than one power company for a given RFI
situation.  May their luck be at least as good as mine was.

Now, my question:  Mike, do you happen to know the story of high voltage DC
power lines?  Late last year, I received an info sheet from a company that
is proposing to construct a high voltage DC transmission system across a
large part of Iowa to carry wind-generated power from the western part of
the state into Illinois.  One of the proposed routes passes near my
property.  (Two things were not defined:  How high is "high" voltage and
just how close to my property.)  I went to the web site and even called an
800 number, but no joy on either issue.  I am guessing that "high voltage"
in this case may mean 1 megavolt, or close to it.  Possible?   Next, corona
issues.  Obviously, no 60 Hz hum with the corona, but I suspect plenty of
discharge streamers.  Comments?  Any insight or info appreciated.

Thanks in advance.

73, Dale
Sr. EMC Engineer


> [Original Message]
> From: RFI Services' Michael Martin <mike at rfiservices.com>
> To: Jim Miller KG0KP <JimMiller at STL-OnLine.Net>; RFI Reflector
<RFI at Contesting.com>
> Date: 6/1/2012 10:01:10
> Subject: Re: [RFI] RFI from HIGH voltage power lines
> Hey Guys,
> The rule is basically, the more insulators the better prepared they 
> are
> the voltage. The number of insulators can be an indication of the 
> approximate voltage but that is not reliable. 230kV is going to have a 
> string of insulators about 8 feet long. That would mean they can apply
> limit. Many times, especially newer construction, they will build in 
> over kill to allow for future growth. The best way to figure the 
> voltage is to follow them back to the station and look at the 
> equipment just inside the fence. Usually the equipment will be marked 
> in some way to help you determine the voltage. Google Earth is a good 
> tool to use to figure out
> direction of the closest station.
> On the average I'd guess, from your description, the range of 138kV.
> a guess.
> As far as noise (RFI) issues, the wood poles are key. Wood shrinks and 
> the loose hardware due to that shrinkage is the main issue of concern. 
> The higher voltage adds to the level and distance it will travel 
> because of
> lesser amount of Line equipment to help filter or dissipate the noise 
> as
> is radiated and conducted down the line.
> RFI caused by power lines isn't usually held to a higher level of
> because of the line voltage, so don't consider that a plus. 
> It is my experience that a utility that is concerned about being a 
> good neighbor, or however you want to refer, is going to fix the issue
> of the voltage. As long as the RFI locating process isn't shot gunned, 
> the cost for repairs on any voltage system is minimum. The costs are 
> usually elevated because of the process they use to locate them and 
> eliminate the sources.
> I know of situations where a utility has spent hundreds of thousands 
> on repairs and not touch the source and then some that spare no 
> expense to learn the correct way to do it to eliminate excessive cost of
> As someone else suggested, go to the area where you are concerned with 
> and setup camp or park and perform the hobby. If you get noise call 
> the
> and see first-hand what to expect from the provider if the condition
> Michael C. Martin
> RFI Services
> 6469 Old Solomons Island Rd
> Tracys Landing, MD 20779
> www.rfiservices.com
> 240-508-3760
> _______________________________________________
> RFI mailing list
> RFI at contesting.com
> http://lists.contesting.com/mailman/listinfo/rfi

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