Estimation of Electric Field in Some Geometric Boundaries
- In a uniform field gap, the average field E is the same throughout the field region whereas in non-uniform field gap, E is different at different points of field region.
- Uniform field distribution is present between 2 spheres of equal diameter when the gap distance is less than the diameter of the sphere.
- Spherical electrodes are frequently used for HV measurement and for triggering in impulse voltage generation circuits.
- In absence of space charges, the average field E in on uniform field gap is maximum at the surface of conductor which has smallest radius of curvature.
- It has minimum field E, at the conductor having large radius of curvature.
- In this case, field is non uniform and asymmetrical as in the case of most practical HV components used in electric power system.
- The mean electric field over ‘d’ distance a between two conductors with a potential difference of V12 is
Eav
= V12/d
In non uniform fields, the maximum electric field Em. is always higher than average value. For some common field configurations, the maximum value of Em and field E. enhancement factor f given by Em/Eav Are presented in table 1 below :
