Ziehesh wrote: ↑09 Jul 2026, 02:05
A good investigation, is it the energy company with a Rode Schwarz spectrum analyzer? Or the GIE?
Try to take the Am receiver to walk along the 0.4 kv line, perhaps somewhere micro-sparking, although in theory the analyzer would have caught, but not always.
And another option is to look for an electric motor, or a pump, most often they are such strong interference in the network, thyristors, or a variable frequency drive.
Recently I started investigating the electrical network by myself using an AM receiver. I used a battery-powered portable radio (Colon RX-8866, AM/FM/SW1-6), mainly tuned to 500 kHz AM, as a simple interference detector.
When the entire area lost power, I repeated exactly the same measurements around my house.
1)Almost all of the previously detectable noise disappeared.
2) My house wiring became silent.
3) Wall outlets became silent.
4) Utility poles that normally produced noticeable AM noise became much quieter (almost no noise).
All of the above was repeated at least a couple of times.
However, even with the whole area de-energized, the underground cable coming from the transformer still produced strong noise when the radio was brought very close to it.
The transformer's grounded neutral (PEN) also continued to produce detectable noise at close range, even though the transformer was completely shut down.
When I powered my PC from a portable power station (with no utility power available), the AM radio immediately detected noise around the power cable of the station itself, which makes me think of two things:
1)Almost all portable power stations and UPSs are not able to provide crystal-clear power quality as advertised, including expensive ones. This made me think that portable power stations also generate noise, which could explain why testing them never changed the main symptom.
2) There might still be significant RF noise present even after the entire area is de-energized. But if that's true, why didn't the UCRF detect anything?
Finally, there is one more observation.
Whenever the utility company performs work somewhere on the electrical network, even if it is not on my own feeder, the behavior of my PC can change dramatically for several hours.
The only possible explanation I could think of is that all 10 kV transformers connected to the same 35 kV network are electrically linked. If one of them generates radio-frequency interference, it could potentially couple onto other lines and propagate through the distribution network.
Another possibility is poor electrical connections or invisible sparking somewhere on the network.
After walking roughly 300 meters around my house, I couldn't find one obvious, strong source. I only found a couple of power poles (not even fed by my transformer) that produced noticeably more AM noise than any of the poles on my own line. When the power was off, they also became silent.
I would really appreciate any ideas about the investigation.