FlightAware Discussions

High voltage line disturbance?

Hi,

I have behind my house at 5/10 meters a high voltage line (THT 400000V), do you think that the radius of these lines (50Hz) can disturb the ADS-B signal in 1090Mhz ?

And if yes they can disturb, put the antenna at a height higher than the high tenssion lines, can solve the problem ?

Thanks.

50 Hz is too low a frequency to be a problem i think.

Also how would you get higher than 10 m? :slight_smile:

If anything they’ll just block some part of the sky a little bit.
But they should have enough air in between to allow signals through.

If you have other buildings or trees around you, placing the antenna higher than them will definitely help.
Be sure to check this thread out: What is the Maximum Range I can Get?
Seeing the horizon from where the antenna is, that’s what you want.

400kv should be much higher than 5-10M. The towers are normally 10+m wide and 40-50m high.

They could cause a number of issues.
If they are used for Internet access then they use much higher frequencies.

I think the magnetic and electric fields could also affect unshielded equipment. The FA dongles are not shielded.

You can use rtl-sdr apps to see what the noise levels are.

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I’m not aware of any data transfer on power lines except for inside the house solutions.

You’ll most likely want a 1090 MHz filter pretty much no matter where you are.
(I’m partial to just going for a filtered LNA, but that’s just me: https://github.com/wiedehopf/adsb-wiki/wiki/Useful-items-for-purchase)

Très Haute Tension THT (French) = Extra High Voltage EHV (English)

Due to safety requirements, the minimum distance to ground at lowest point of conductor of a EHV line should be greater than about 9m. This is the lowest point on the sag. At supports, it is much higher (about 20m), as the wire is a catanary due to long span (250m ~ 400m between towers)

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Permissible Minnimum ground clearance (Zmin in above sketch) of conductors of Electrical Lines

KV Ground Clearance Over Highway
66 KV 6.1 Meter 8.0 Meter
132 KV 6.1 Meter 8.6 Meter
220 KV 7.0 Meter 9.8 Meter
400KV 8.8 Meter 10.8 Mete
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BPL Broadband Over Power lines.


They can also use them to monitor smart meters and other devices.

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Hmm, don’t think below 100 MHz is much of a problem as typical ADS-B antennas don’t pick that up well.
Also radiated power shouldn’t be that high?

Thanks to all for your reply !

I have my Antenna on the top of my roof (it’s a house), i used a 1090 filter and an Amplificator (this one : the Uptronic 1090MHz ADS-B Ceramic Filtered Preamp).

In fact I asked myself this question because I noticed that in the axis of the high voltage lines, I capture less well, while it’s this axis which is totally cleared (fields) and without any obstacle apart from the power lines.

You have pretty much equal range in all directions looking at your stats.

Have you checked how the terrain is?: What is the Maximum Range I can Get?
Even fields can have rising terrain.

Any interference would affect all directions!
So if the power lines are a problem, it’s just because they are an obstacle.

You can get problems if an insulator on the power line is failing and starting to arc over. This acts as a spark transmitter radiating wide band interference.
It will affect lower frequencies more than high frequencies and I would think it is unlikely to cause a problem with ADSB. Usually you can hear an insulator that is failing especially if it is misty. Power companies are usually pretty good (in the UK at least) at replacing failing insulators if reported. They don’t want them to fail catastrophically and then have a power outage. Power outages cost them money in fines from the regulators.

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Even if the insulator is not failing, when humidity is high, there is a discharge ove insulator surface, called corona discharge.

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Power lines don’t put out too much un-controlled, HF, interference, all those are losses to them and minimized - even the Corona ones.

What they have is communications over the wires, in the old times it was used a RF carrier in the range of hundred kHz. I used to do preventive maintenance on their equipment.

Lately all that (or almost all) was converted to optical communications - the lightning protection conductor is a composite fiber optical/steel one:

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The line traps were used to separate/inject communication frequency carrier signal (40 kHz to 1000 kHz) to power line which also carried power frequency (50 or 60 Hz) current.

The line trap were basically parallel resonant circuit comprising of coils & capacitors.

Picture below shows these line traps: the cylindrical things hanging from tower cross-arms.

They were out there, and may still be in ‘selected’ US states. I seem to recall reading that most were being shut down due to the severe interference they caused.

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Isn’t that beautiful?
The injection capacitors were on the ground, part of the capacitive voltage transformers.

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