Power Line Structure

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Even a P3A plagued with compass errors is still flyable (this is the 3rd craft DJI sent me...which is still defective)

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I tried once to take off close to a high voltage power line and my bird said NO WAY and didn't even arm the motors. I live out in the country and besides the road is a 14,400v power line and if I get too close my P4 want to align it's self with the lines, I was about 30 feet above them in a hover and the bird slowly flew directly over them and stayed there and maintained altitude on it's own, I was able to bring it back but I had to push far on the stick. The magnetic flux generated from the lines will screw with your bird. So Northern guy, if you are close to 230 k volt line your birds compass will be affected, if you don't believe this go with a hand compass and stand close to these lines and report back to us what the needle did.
 
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This happened to me several weeks ago. I tried to launch near main voltage lines because its right next to an open filed thats great for practicing. I was getting compass errors and GO would not even arm the props for flight. Did my compass calaberation and didn't fix it. I then went to another field about 100yds away and everything was fine. Confusing thing is I launched from that same point about a month prior, on a late afternoon and had no issues. I think it just depends at that moment if high voltage electricity is flowing through those lines. I'm guessing it just fluctuates throughout the day.
 
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Magnetic induction would vary with the amperage, or load.
 
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I too have had compass error problems, but mine were caused by flying above 15m steel streetlight poles at about 25m. I still don't understand why it has to switch from gps to atti on a compass error. It is certainly disconcerting when it suddenly changes & begins to drift with the wind. That is a good reason why we all need to be proficient in flying atti mode. Any large steel structure will become magnetised by the earth's field, and/or any current flowing through the conductors in a high voltage line, but my experiences suggest that it is the [semi]permanent magnetisation of the actual structure which causes the most problems.
 
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I too have had compass error problems, but mine were caused by flying above 15m steel streetlight poles at about 25m. I still don't understand why it has to switch from gps to atti on a compass error. It is certainly disconcerting when it suddenly changes & begins to drift with the wind. That is a good reason why we all need to be proficient in flying atti mode. Any large steel structure will become magnetised by the earth's field, and/or any current flowing through the conductors in a high voltage line, but my experiences suggest that it is the [semi]permanent magnetisation of the actual structure which causes the most problems.
It has to switch to ATTI because without the compass, it doesn't know which way it's pointing. GPS only tells it where it is at any given time, not which way to go.
 

Mark The Droner

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Yes. It's like waking up hungover in pitch darkness after sleeping on the floor at a frat house. You know where you are, but which way is the door?
 
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People, 230 kV AC lines really won't do anything to your compass, during this flight section no errors were reported. AC changes polarity 60 times per second, thus a compass remains still. If I was flying over a dc line that's another story.


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People, 230 kV AC lines really won't do anything to your compass, during this flight section no errors were reported. AC changes polarity 60 times per second, thus a compass remains still. If I was flying over a dc line that's another story.


Sent from my iPad using PhantomPilots
That's right. The frequency response of the magnetometers irolls off well below 60 HZ. But, I was surprised to find out that some power lines have a magnetic field that oscillates within the magnetometers frequency response. The oscillation in this plot is 1.44 HZ
upload_2016-10-24_16-25-23.png

and is occurring when the P3 comes close to these power lines.
upload_2016-10-24_16-26-28.png


My theory is that this 1.44 HZ oscillation is excited when load and generator is slightly out of phase. I'm just rambling here, I know almost nothing about electric power generation and delivery. But, I do know this is just a magnetic field, not an electromagnetic field, since at 1.44 HZ this is clearly the near field effect.
 
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People, 230 kV AC lines really won't do anything to your compass, during this flight section no errors were reported. AC changes polarity 60 times per second, thus a compass remains still. If I was flying over a dc line that's another story.


Sent from my iPad using PhantomPilots
Your right about the dc volts and EMF. AC will cause electrical fields EF, but they still affect the compass, these fields will not travel as far as emf (dc) but still will cause your birds compass to be affected (if you are close enough). Many of us have had this condition affect our bird.
 
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I have powerlines right next to my home I have flown near them but not over them with no problem
 
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It's also worth noting that technology is changing and some high voltage transmission lines now have DC power flowing through them.
 
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That's right. The frequency response of the magnetometers irolls off well below 60 HZ. But, I was surprised to find out that some power lines have a magnetic field that oscillates within the magnetometers frequency response. The oscillation in this plot is 1.44 HZ
View attachment 67657
and is occurring when the P3 comes close to these power lines.
View attachment 67658

My theory is that this 1.44 HZ oscillation is excited when load and generator is slightly out of phase. I'm just rambling here, I know almost nothing about electric power generation and delivery. But, I do know this is just a magnetic field, not an electromagnetic field, since at 1.44 HZ this is clearly the near field effect.

Interesting, thats quite the array of low voltage lines on the pole, some maybe 66kV and some other lower voltage stuff on the arms. Multi circuit and a whole bunch of harmonics going on.
 
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