Brian,
The last paragraph is particularly interesting. Variable speed drive
motor controllers are well known noise generators, primarily because
they are generally very poorly installed in a manner that their wiring
forms loops with a large loop area, establishing strong magnetic fields
that strongly couple harmonics of the square waves used to control the
motors. The fix is to reduce the size of the current loop.
It would be interesting to know if any of this might be part of the
problem at the wind farm near ZL6QH. I'm forwarding this email to the
RFI reflector.
73, Jim K9YC
On Fri,4/1/2016 5:22 AM, Brian Miller wrote:
Thanks Frank
I was previously the chair of the Quartz Hill User Group responsible for the
ZL6QH station.
We undertook measurements of the noise from the wind farm at the ZL6QH site. A
report on our measurements is published at
http://www.zl6qh.com/rf-noise-measurements-quartz-hill-2009-v3.pdf .
The ZL6QH wind farm used Siemens 2.3 MW variable speed turbines. We believe
the noise was generated by the water cooled electronic power converter
technology that was used to convert the variable output of each turbine to the
fixed voltage and frequency of the national grid.
Our observations suggested that a HF contest station would have be located at
least several km from a wind farm using these turbines to reduce the
interference to an acceptable level on the low frequency bands.
But not all turbines are this noisy. We also conducted some HF radio frequency
noise measurements at the Meridian Energy Te Apiti wind farm (near Palmerston
North) in October 2005 but found no evidence of any significant noise being
radiated by the turbines, even at locations within 100 metres of the nearest
turbines. Unlike the turbines at Quartz Hill, the Te Apiti turbines were a
fixed speed design and did not use a separate power converter unit
73
Brian VK3MI ZL1AZE
------------------------------
Message: 7
Date: Wed, 30 Mar 2016 15:59:34 -0400 (EDT)
From: donovanf@starpower.net
To: TopBand List <topband@contesting.com>
Subject: Re: Topband: Wind Farming
Message-ID:
<990159030.6273859.1459367974629.JavaMail.root@starpower.net>
Content-Type: text/plain; charset=utf-8
The Quartz Hill Contesters -- once very well known as ZL6QH --
were forced to shut down their spectacular contesting location
by the RFI from a wind farm installed in the same location as
their contest station.
http://zl6qh.com/logs/Quartz%20Hill%20Pictures%20-%20%20March%202010.pdf
73
Frank
W3LPL
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