moored under electricity pylons, boat hull vibrating!

[Jim Riley]

But was he actually stealing, did his "demand" on the system drop the output at the far end of the cables. And how did they know? If it was a "pattern over time" that triggered the visit his barn wasn't mobile.

[dmr]

 

No, because the canal is a different distance to each line this give the 50Hz. The vectors rotate in a.c. and are out of phase by 120 degrees so don't cancel giving 150Hz - best to think of it in the time domain anyway.

 

Its a linear system, if we add (or subtract) two (or 3) bits of 50Hz electricity then we get a different size bit of 50Hz electricity. Adding is a linear operation. Only a non linear system can generate a new frequency. Draw it out in the time domain!

 

..............Dave

[AndrewIC]

Tootling along the Macclesfield one summer in fine dry weather, there is a stretch that runs under power cables. I was steering with my forearm resting aling the shiny brass tiller tube, and started to get tiny shocks off the tube!

[Tiggs]

 

Its a linear system, if we add (or subtract) two (or 3) bits of 50Hz electricity then we get a different size bit of 50Hz electricity. Adding is a linear operation. Only a non linear system can generate a new frequency. Draw it out in the time domain!

 

..............Dave

 

3 phase waveform diagram

 

As you can see 3 peaks in every 1/50th of a second (sorry US diagram for so 60 Hz). i'm not going to argue anymore, no matter what you say I know I am right.

[Greylady2]

But was he actually stealing, did his "demand" on the system drop the output at the far end of the cables. And how did they know? If it was a "pattern over time" that triggered the visit his barn wasn't mobile.

Helicopter pylon inspection they have a lot of techy stuff to check hotspots.

 

I saw them 3 week ago doing it very low altitude.

[zenataomm]

But was he actually stealing, did his "demand" on the system drop the output at the far end of the cables. And how did they know? If it was a "pattern over time" that triggered the visit his barn wasn't mobile.

 

Yes they knew they were losing something along the way and a helicopter with infra red imaging had focussed on the barn.

He was done for stealing because he'd built an apparatus for the sole purpose of harvesting somebody else's property.

[Greylady2]

Yes they knew they were losing something along the way and a helicopter with infra red imaging had focussed on the barn.

He was done for stealing because he'd built an apparatus for the sole purpose of harvesting somebody else's property.

Clever Farmer, he should of put some pretend solar panels in his fields and sold the power back to them.

 

Where theirs muck theirs money.

 

Edit : this is only humour you electric people.

Edited July 4, 2016 by Greylady2

[zenataomm]

This was long before solar panels, and the fact he was a retired officer in The REME with more than the necessary qualifications and experience which didn't bode well in his defence for supporting a "Didn't understand what was going on .... Yer 'onour!" plea.

 

I did consider something similar under the clothes of my Butty, but knowing my luck I'd have induced the wrong field and ended up with a giant electro magnet which in turn would sink the boat under the weight of all the discarded bicycles and supermarket trollies reacting to it.

[dmr]

 

3 phase waveform diagram

 

As you can see 3 peaks in every 1/50th of a second (sorry US diagram for so 60 Hz). i'm not going to argue anymore, no matter what you say I know I am right.

 

But this is a technical discussion, one can argue about politics (though no longer on this forum) but one can't really argue about engineering because no matter how much one does argue the result can not be changed.

OK, if we have three guitars and each plays a middle C at the same moment then what note would we hear?????

I know of at least one forum member who does have three guitars on his boat so maybe he will help here.

 

..............Dave

[sharpness]

I know of at least one forum member who does have three guitars on his boat so maybe he will help here.

 

..............Dave

But does he have 3 hands to play them all at once?

[dmr]

But does he have 3 hands to play them all at once?

 

Strictly he would need 6, but maybe he could just move really quickly.

 

...............Dave

[NilesMI]

Yes. If guitar strings of the same frequency, but different phase, interfered with each other to create a note of different, higher, frequency we would all have to play in phase. Somehow.

 

But my explanation would be analytical.

 

 

Tiggs is correct that the pylons will carry three separate phases and that the time interval between the successive phases is 1/150th of a second. But it doesn't follow that the net effect of the 3 phases added together is a field with a frequency of 150Hz.

 

In general if you add two sinusoids which have the same period, the result will be a sinusoid with different amplitude and phase, but the same period.

 

The maths is shown here

 

Clearly, adding a third sinusoid with the same period, will result in yet another change of amplitude and phase, but the period will be unchanged.

 

Dave123's boat was sitting in a field which was oscillating at 50Hz.

Edited July 5, 2016 by NilesMI

[Tiggs]

 

But this is a technical discussion, one can argue about politics (though no longer on this forum) but one can't really argue about engineering because no matter how much one does argue the result can not be changed.

OK, if we have three guitars and each plays a middle C at the same moment then what note would we hear?????

I know of at least one forum member who does have three guitars on his boat so maybe he will help here.

 

..............Dave

 

OK Dave, I get it now. I was wrong and you are right. I was thinking about it in the wrong way.

 

The field you would end up with would be zero if the distance to each wire was the same, if you look at a peak of one phase the other two cancel it out. What you end up with is a field from the nearest one is partially cut back from the other two and what you get is a 50Hz field.

[Phil Ambrose]

OK, guitars aside, I can recall that when I was racing (cycle) on more than one occasion during a 24 hour race when traveling across the fens it was not uncommon to feel a tingle nor to see pylons gently arcing to the ground, particularly in warm humid weather this was of course during the night. We would joke about "getting a buzz out of it"

Phil

[Bod]

Should you get the chance, watch the high voltage pylons on a foggy night, the blue arcing and buzzing, can be spectular.

I have felt this slight vibration on the brass hatch rails when passing under high tension cables, only happens when the wires are in use.

 

Bod

[I Spartacus]

I knew someone who made a battery charger out of some coaxial cable and PTFE tape and charged his battery over a few days

BT lines run off DC I think he tried to use that as well but got caught. It is funny that plants and trees grow much faster

under HV power lines, I don't think it would do the body much good living in a high magnetic field all the time

[dmr]

I have heard that in the days of the Berlin wall a man crossed from East to West by dropping down from a pylon on to a cable and pulling himself along the cable over the wall. Only effect reported was a tingling in his bumhole, but if I was hanging on a cable with armed guards everywhere I reckon my bum would tingle regardless of the electricity.

 

.............Dave

[Chewbacka]

Live working on HV cables by helicopter.

Have a look at this video from about 1:10 where you can see the spark from the HV cable as the man & helicopter charges up.

He has an impressive suit as well.

[Dave123]

Interesting video!

and I am impressed by the amount of knowledge everyone has on here about so many topics it seems!!

[MankySteve]

It is funny that plants and trees grow much faster

under HV power lines

Probably just because people don't go messing about with tress under pylons also don't tend to built on colleration doesn't allways mean causeation.

 

There no sciencetific evidence between the effects of low level EM fields and human health.

[tree monkey]

Probably just because people don't go messing about with tress under pylons also don't tend to built on colleration doesn't allways mean causeation.

There no sciencetific evidence between the effects of low level EM fields and human health.

I used to mess with trees under power lines all the time, mind you I was paid to do it

[cuthound]

In the early years of my career, when I was a power maintenence technician, the room we used to stay in had a 1MW transformer in it and 10 2000 amp DC rectifiers (to provide float and charging for the batteries.

 

Never did me any harm, except for growing another head.

[dunfixing]

Not that I recommend it.

But it is possible to get free electricity from overhead power lines, all you need is a coil of wire and a suitable step down transformer.

The effect on your boat is through induction and your steel would act as an electro magnet, add a coil of wire and you have a transformer.

I would not recommend you try as it could be dangerous if you do it well enough.

[tidal]

Some years ago I sailed a steel salty boat along a stretch of river crossed at intervals by power lines.
The effect on the two deck compasses was, to say the least, quite dramatic.

 

Whist they seemed to have no lasting ill-effects I had them swung again just in case.

 

 

I lived directly under some power lines for the first 12 years of my life and the buzzing they created in mist and fog is one of my most abiding memories

[ditchcrawler]

I know a boater who will not moor under them, to use his words "They do my head in"