P4 & medium voltage overhead power lines

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I have to fly on a field in which, along a side, there's a medium voltage overhead power line.

The poles are high about 10 meters. The flying height will be not less than 50 meters from the ground below. The take-off point is close to the power line.

My idea is to manually take off and to reach the flight altitude (50 meters) avoiding passing near the power line, and, only reached 50 meters, to start the automated flight with Litchi.

There may be interferences ? At what distance ? I will stand with remote control almost just under the power line...
 
I would advise against flying anywhere close to power lines of any description. The EMF they generate will almost certainly screw with the RC and the Drone. I recently crashed my P4 on a Litchi Mission when the drone was about 20m away from power lines, it went totally out of control, couldn't regain control at all and it ended up upside down in the field.
 
I presume you're in the USA. I would think that your typical 110kv US cables do not generate a huge signal and you'd be OK at >100 feet above them. Our UK National Grid system carry both 275 and 400kv so produce substantially more EMF and I would not be flying within 1/4 of a mile of them in any direction. I regularly fly near local wooden poles that carry 11kv and have never had an issue..
 
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The line is 20 kV.

I am very confused about the issue because I read very mixed opinions. On YouTube is full of videos of people using drones for inspecting high-voltage lines very closely without problems and there are people who said they had lost control of the drone just a few dozen meters away from a medium-voltage line.

What is the truth ?
 
There are many threads on this topic and from my own experience, unless you are very close, nothing will happen. I routinely fly near an 11kv line on the way to my favourite filming spot and have zero issues. A chap posted a video of a litchi flight that flew within metres of what looked a 220kv line and it kept going. Obviously you need to be sensible when planning your flight but there is a bit of hysteria regarding emf and the like.
 
My guess is that it is not going to be the electric field that causes problems, but rather the magnetic field that may affect the compass. Since the magnetic field is determined purely by the current, not the voltage, there may be little direct correlation between interference and line voltage. For similar power transmission, higher voltage lines run at lower current (since P = VI), but on the other hand higher voltage lines are typically intended to run at higher power. Actual line load may also be quite variable, which may explain the disparate results that have been reported.
 
I found this one.


compbt.gif


With a 20 kV power line a safety distance of 30 meters from the line should be enough. Or am I wrong ?
 
My guess is that it is not going to be the electric field that causes problems, but rather the magnetic field that may affect the compass. Since the magnetic field is determined purely by the current, not the voltage, there may be little direct correlation between interference and line voltage. For similar power transmission, higher voltage lines run at lower current (since P = VI), but on the other hand higher voltage lines are typically intended to run at higher power. Actual line load may also be quite variable, which may explain the disparate results that have been reported.
The frequency of the magnetic field is 60 Hz which is too high to have any affect on magnetometers in the P4. At least if the P4 has one of the commonly used magnetometers. But, then I was surprised to learn that power lines sometimes do have lower frequency magnetic fields. Here is the Z axis magnetometer data from an incident where the compass was the cause.
upload_2017-4-7_4-32-19.png


That frequency is 1.5 Hz and it occurred as the AC was flying past some power lines.
upload_2017-4-7_4-33-40.png

I'm not a power distribution guy but I'm supposing the load and source were in some kind feedback loop. Either that or the load varied at 1.5 Hz
 
The frequency of the magnetic field is 60 Hz which is too high to have any affect on magnetometers in the P4. At least if the P4 has one of the commonly used magnetometers. But, then I was surprised to learn that power lines sometimes do have lower frequency magnetic fields. Here is the Z axis magnetometer data from an incident where the compass was the cause.
View attachment 80022

That frequency is 1.5 Hz and it occurred as the AC was flying past some power lines.
View attachment 80023
I'm not a power distribution guy but I'm supposing the load and source were in some kind feedback loop. Either that or the load varied at 1.5 Hz

I haven't seen any specifications on the bandwidth of the accelerometers, or on their response to 60 Hz magnetic fields. But even if they are designed to ignore alternating fields, if the alternating field strength becomes too high then the response of the sensor may become non-linear. I wonder if the observed 1.5 Hz variation in the sensor output is actually in the sensor response rather than a real frequency component in the magnetic field.
 
I haven't seen any specifications on the bandwidth of the accelerometers, or on their response to 60 Hz magnetic fields. But even if they are designed to ignore alternating fields, if the alternating field strength becomes too high then the response of the sensor may become non-linear. I wonder if the observed 1.5 Hz variation in the sensor output is actually in the sensor response rather than a real frequency component in the magnetic field.
That's a good point. If I can get some time maybe I'll set up an experiment. Shouldn't be too hard to split and place one side of an AC cord next to the magnetometers. Then drive various loads to see if there is an effect on the mag data.
 
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I planned a flight that does not come close less than 50 meters from the 20 kV line.

I hope it's enough...
 
I presume you're in the USA. I would think that your typical 110kv US cables do not generate a huge signal and you'd be OK at >100 feet above them. Our UK National Grid system carry both 275 and 400kv so produce substantially more EMF and I would not be flying within 1/4 of a mile of them in any direction. I regularly fly near local wooden poles that carry 11kv and have never had an issue..
Actually, this didn't jibe with my memory -- I recall from somewhere that the US uses 500kV quite a bit for efficient long-distance transmission. Checking Wikipedia (and assuming it's correct), it states that in the US HV transmission lines are generally 230-500kV.

So the EM interference risks sound to be about the same as in the UK.
 
The line is 20 kV.

I am very confused about the issue because I read very mixed opinions. On YouTube is full of videos of people using drones for inspecting high-voltage lines very closely without problems and there are people who said they had lost control of the drone just a few dozen meters away from a medium-voltage line.

What is the truth ?
20kV is nothing. The power lines overhead in your neighborhood -- in the US -- carry 7-10kV, which is stepped down by that transformer on the pole near your house to 3-phase 220.

If 20kV produced enough EM radiation to mess up your Phantom -- similar to an EMP in general concept -- then there would be thousands upon thousands of out of control, crashing drones, everywhere.
 
I've flown near power lines quite frequently without any difficulties. Check the last 30 seconds of the video below. (At about the 2:50 point)

I was doing a live track and never considered the power lines that I drove under. (The whole video kind of boring.. just me driving around in my Jeep). But note at the end, the Phantom wasn't bothered in the least by the proximity to high voltage lines.

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