Mohammad_Pirzadi
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The question about "wireless power transmission" (should be better designated inductive coupling) has been already answered. You need to calculate actual field parameters. Probably 95 to 99.9 percent of the magnetic field generated inside the tube will shorted by the steel wall. So it's very little of "power transmission".
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Instead of "thinking" you should better start to calculate.
Talking about "waves" is already confusing the problem, for distances below some 1000 km, there's only a magnetic near field. Respectively the potential EM problem reduces to a pure M field problem. But as a matter of fact, steel has high µr and only very small part of the magnetic field can penetrate the tube wall.
If you can give dimensions the dimensions of your reference pipe, someone might be motivated to do the calculation. However, as already mentioned, I believe that this calculation is an essential part of your project job, and in my view the thing to start with.
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Making resonant transmitter and receiver coil circuits is all very well, but you seem to read magical properties into it.
Most notably, a resonant coil can only receive a field that actually reaches through the tube wall. On the transmitter side, it frees the driver circuit from supplying reactive power to the coil inductance, it does not reduce the resistive coil losses or the eddy current losses in the pipeline tube.
Instead of "thinking" you should better start to calculate.
GPS = Global Positioning by Satellite but I said GPR.
GPR = Ground Penetrating Radar.
Intense but narrow beam pulses are directed into the ground from a mobile (sometimes hand held) device and the timing and intensity of echoes gives you the distance to and density of underground structures. GPR would tell you where the pipe was but not the PIG inside it but if the PIG vibrated the pipe wall in some way it would show as a modulation on the GPR reflection and that could be used to find it's location.
VLF acoustic waves may pass through the wall of the pipe but EM waves will be highly attenuated as FvM explained. If say 99.9% of the signal didn't reach the outside of the pipe, the chances of the remaining 0.1% being detected through 5m of soil as well is almost zero.
Brian.
The difficulty is that the inductive coupling between two coils only works provided there is nothing in the way that provides a much easier and shorter magnetic path for the magnetic field than through the remote coil.
View attachment 133696
A two inch steel pipe (shedule 40) has a 3.9mm wall.
A twelve inch shedule 40 steel pipe has a 10.3mm thick wall.
Larger pipes are even thicker.
As stated earlier, the main near field coupling medium at these frequencies will be completely magnetic.
It seems pretty unrealistic to expect the available energy from a couple of AA cells to magnetically penetrate at least 4mm of mild steel.
If you try to induce an eddy current around the circumference of the pipe, I cannot see how there would be much of a magnetic field extending beyond the pipe itself. The magnetic flux will find a much easier path through the steel than radiating out externally.
In answer to an earlier question about what moves the pig. The pig is like a free piston in the pipe, it moves along the pipe as the fluid moves. Sometimes there might be a different type of fluid ahead and behind the pig, so you can use the same pipeline to alternately transfer very different fluids with very little mixing.
In a gas pipeline, water or condensate sometimes accumulates at low spots which can be a problem. Passing a pig through the line powered by differential gas pressure, will sweep any water ahead of the pig and clear the line. This is often done on a routine basis.
otherwise I see the best solution being to induce a current into the pipe by treating it as the secondary of a very low impedance transformer.
which frequencies can pass metals and soil with the lowest attenuation???s
So vague the question, so incomplete the answer.DC (zero frequency) is blocked by a conducting enclosure- the electric field is not felt outside.
no, but it's something likes that.Is this related to cable location?
So vague the question, so incomplete the answer.
E-field is blocked, DC M-field passes conductive enclosures, but is affected by ferromagnetic metals.
That depends on the coupling medium, and what you are trying to do.
Three possibilities.
Direct electrical coupling through stakes driven into the ground.
Magnetic coupling through coils.
Electromagnetic coupling through antennas.
All are very different and each presents unique problems.
do you have any functional idea??? I'm so tired by this project but I must complete it till February 2017.Found a manufacturer's article giving some quantitative data about relation of wall thickness and detection distance. https://www.pigging.tools/Aprodit-Article2-en_Using_Devices_for_Finding_a_Pig.html
It shows that the intended project specification is basically feasible, but also that the field attenuation by the pipe walls is rather challenging. It seems usual to specify the detection range of low frequency electromagnetic pig transmitter/receiver systems by a free a air range. This allows a simplified calculation of design properties.
Thanks a lot, I think utilizing of magnetic field is the only way. in this way, I am thinking on Wireless Power Transmitter (WPT) method. now I have 2 questions:Electric currents can be sent through soil directly, mainly due due to moisture, most soils are electrically conductive to a greater or lesser extent.
If you drive stakes into the ground separated by some reasonable distance, and pass a current between them, the current does not all travel in a direct path, but spreads out horizontally and vertically in a large cross section.
These currents can be detected at a distance by driving other stakes into the ground, so its possible to communicate through the ground directly without wires over some short distance. All this requires a direct electrical connection to the ground. Its interesting, but not particularly useful.
Another method is to generate a low frequency magnetic field around a coil. If there is another coil in the vicinity, the signal can be received. The magnetic field always takes the easiest path, and may be readily distorted by magnetic objects.
And that would be very unfortunate for you if one coil is surrounded by a thick steel pipe. In this case the coupling will be entirely magnetic, no direct connection to the ground is requires, so hand held receiver is possible.
Third method is by electromagnetic propagation (radio waves) which is also non contact, but it requires a very log antenna at very long wavelengths to work efficiently. At 22 Hz a half wave antenna would need to be roughly 7,000 Km long, which is obviously a practical impossibility.
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