Rossi
Your friend's problem might be similar to the one our EMC lab had in
California during the dry season. We were measuring ambient radiated
broadband noise in the .1-200 MHz region that had not been there
earlier in the year. We checked building wiring, we replaced some
fluorescent light balasts, we looked for corrosion on AC power
terminals and ground lugs - no improvement. The noise on the
spectrum analyzer looked like a group of lines sweeping across the
screen, which would become stationary when the spectrum analyzer
trigger was set to LINE. The interference made a buzzing noise on
the receiver.
The local power company said the noise was caused by dirty power line
insulators. The dust and dirt accumulates during dry weather and
makes an intermittent conductive path. The high voltage arcs over
this poor path, making the characteristic spark-gap emitter noise we
were seeing on the spectrum analyzer.
The power company came by and washed off the insulators on the power
poles, and once they were clean, we did not experience the
interference.
Hope this helps. BTW, they used special trucks and I believe a
non-conductive liquid to do the job.
Best regards
Tom Cokenias
T.N. Cokenias Consulting
P.O. Box 1086
El Granada CA 94018
tel 650 726 1263 fax 650 726 1252
Rossi Giuseppe wrote:
>
> Dear collegue
> I've got a question to which I'm not able to responde:
> A friend of mine is complaining about the EM radiated
> (not conducted) noise coming from a electrical generation
> power plant ( I do not know the exact translation, hope
^^^^^^^^^^^
?????
> that is anyway clear) He told me that the phenomena
> is particulary annoying in case of dry weather and that
> there is no noise in case of rain or fog.
>
> Could you give me any hint or point me toward something to read ?
Nute: [email protected]
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