Plane problem of electrostatics.
The diameter of the cable with insulation is 20mm (for all cables).
The insulation thickness is 2 mm.
Relative permittivity of individual insulation ε = 3.3;
Relative permittivity of common insulation ε = 3;
Voltage applied UA = 9.8 kV, UB = -4.9 kV, UC = -4.9 kV.
Determine the field strength, potential in cable and in insulation.