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impedance of a pipe, skin effect
Original poster: =?iso-8859-1?Q?=C1lvaro?= Aballe <aaballe-at-eupecespana-dot-com>
Dear tesla experts,
First of all, I should say that I am a chemist (no familiar with what you
may normally talk here). However, I think you can help me a lot.
I would like to know what is the impedance of a pipeline (about 10-mile
long buried pipe (0.375 inches thick) made of steel (ferromagnetic)
carrying natural gas or oil).
There is a rectifier having one of these leads connected to the pipe, and
the other lead connected to a grounding system: so a 120Hz rectified
current is going through the ground into different points of the pipe (with
damaged coating) and coming back to the rectifier through the pipe.
I understand that I should not considered the system as a transmission line
because is too short (10 miles or so) compared to the current frequency
(120Hz).
Is the impedance for a pipeline the same as for a cylindrical conductor (no
hollow)? That is; is the Z= (1+j)/(s·d); s=conductance, d=skin depth,
valid?. Can I apply this equation even for low frequencies such as 120Hz?
From Z= (1+j)/(s·d), I can obtain the internal inductance and the surface
resistance..Are there any other factors to consider (external inductance,
coupled inductance)?
Thanks a lot.
Alvaro Aballe