Jump to content

Independant earth electrodes


baltoche
 Share

Recommended Posts

Dear electician friends,

 

Suppose I have got two horizontal ground grids laid at the same depth and separated by a distance "d". How to calculate "d" so that my grids are independant from each other, meaning that I can bond them together and calculate an equivalent resistance by 1/(1/R1+1/R2) ?

 

With my thanks !

Link to comment
Share on other sites

Hi again,

 

there are still many ways to understand you description... I suppose at least that a grid consists of many wires in the ground.

 

If the resistance of one grid results mainly from spreading the current near the wires, then you need only the other grid to be a few wire diameters away. That is, you could just as well have a single grid with twice as many wires and obtain half the reistance - logically enough for this case.

 

If you have enough wires that the resulting resistance resembles one big solid electrode occupying the same ground area, then the second grid must be a few area diameters away from the first one.

Link to comment
Share on other sites

I indeed assumed that a grid consisted of a loop (with intermediate crossbonds) of round copper or steel buried in the ground and occupying a given surface (Lxl). During an MV fault, part of the fault current will be dissipated in the ground through this grid (called A). At the same time, another part of the fault current will dissipate in the same ground through another nearby grid (called B). I guess that my influence zone related to grid A depends on the fault current dissipated through A besides the geometry of the grid itself. Same case for grid B.

Is there a way to assess the respective influence zones of grids A and B from a geographical point of view so as to assess the overlap between them ?

 

Thanks and Regards.

Link to comment
Share on other sites

Suppose that you bury enough wire length, so the mesh behaves nearly as a solid sheet, which you model as a radius=R hemisphere only because it's manageable. Choose R for 2piR2 = L*l for instance.

 

For some current injected by electrode A raising a voltage V there, you get a voltage V/n at the electrode B distance from A by n*R, so choose n.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.