Power line interference and other questions

[Reloader]

Thanks for the info. I plan on staying well above them to get to the other side of my property.

 

[jephoto]

Dumb question but does H go to a negative number if you launch from a high point and go down?

Yes.

 

[REStewart]

I have an MSEE with emphasis on the Power sector of EE. Your biggest danger is running into the lines, not picking up interference from them. The comment about current level increasing magnetic field is absolutely correct; but should only result in compass issues and only if you are dangerously close. An EE friend of mine working in computer design once asked me what high frequency was to a power engineer? I told him that most power engineers in North America would say 60.1Hz is high frequency!!

 

[David_Cambridge]

All high voltage lines are alternating current (Ac). The magnetic field is reversing itself 60 times per second. Unless something sudden happens I less than 1/60 of a sec, there should be no impact on the compas. In fact, when something has been magnetized, an alternating magnetic field is used to demagnetized the object.

 

[Unique]

I recently purchased a Phantom 4 mostly just to fly around on
Some property I own. There is a high power transmission line that runs across the property. Are there any issues to be concerned about other than collision? I would like to fly over the lines to reach the far side and f my property, but am a bit concerned with getting a lost signal.
Also the property is quite steep. Will the obstacle avoidance sense the hillside and avoid colliding with it?
Altitude: Is the altitude readout from the ground under the done, or from sea level?

I have flown over power lines for without loss of signal, or other major issues. I was shooting photos for a survey project so I was flying in a grid pattern taking shots at set time intervals. I loaded the photos into software which shows the position of the photos and saw that each time the drone passed the cables, it dropped a couple metres, then climbed back to the normal altitude. It repeated the same behaviour on each pass. I didn't notice it during the flight.

So it obviously affected some instruments in the drone, but not anything major. Whenever I fly over power lines, I just make sure there is plenty altitude over them to reduce risk. I'm always a little more cautious around power lines.

 

[REStewart]

Hey David, you are absolutely correct about AC magnetic fields. However, as you note there are asymmetrical events and traveling wave phenomena that can affect electronics. Power line inspection and monitoring is very effectively done with drones proving interference is not a major issue. My thought was just be cautious and pay attention. The biggest risk to a UAS still is running into the line and crashing.

 

[Andy9]

If you care to read carefully, my confusion was what was the difference on “ height above ground and elevation above launch point”. Don’t know where you read me claiming to be airline pilot.

OK. You should know by now the difference. However let me put another example. The difference is important where the ground is not absolutely horizontal. And such is almost everywhere.
Let's say that you take off on a big meadow and hoover at 10m. It seems that the ground is levelled which is seldom true. Usually it goes up and down and if you fly in straight line for a few hundreds meters, eventually you can hit the ground having those 10m on the display. That's why it is important to have the drone in VLOS.