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Hi,

I am trying to generate plots for the electric and magnetic field inside a void in an 11kV three phase PILC (paper insulated lead covered cable). I'm new to COMSOL and running version 5.0. The model is 2D and the void is about 1mm in diameter (very small compared to the cable).

Basically I need help with:

- Choosing the relative permittivity (epsilon r) of the insulation and void in the cable. I have currently plotted the electrical field in the whole cable (which looks ok using a permittivity of 6 for the insulation) - but I cannot get the void to behave correctly. It should concentrate the field but at the moment the field exactly the same as without the void, not disturbance whatsoever. Any ideas what the er should be inside a void?

- Choosing the relative permeability of the insulation and void in the cable, basically so that I can do the whole thing over again with the magnetic field. I really have no idea what sort of values I need here.

- Plotting the field on the void surface and boundary ONLY, not in the whole cable as well. I'm new to COMSOL so don't quite know how to go about this. I think I need to define a new data set and then just plot that, but I'm not sure which data set type I need.

Btw, this model is just for a basic rough idea of what things look like, so the permeability and permittivity are just ball park figures for now.

Thanks in advance for any help.