# Bushing insulator

3-phase bushing insulators 10kV rated are installed on the transformer tank cover.

Problem Type:
3D extrusion electrostatics.

Geometry:

Given:
Relative permittivity of air ε = 1,
Relative permittivity of oil ε = 2.2,
Relative permittivity of insulator ε = 6,
phase A electric potential UA = 10000*√2/√3 * cos(0) = +8165 V,
phase B electric potential UB = 10000*√2/√3 * cos(120) = -4082 V,
phase C electric potential UC = 10000*√2/√3 * cos(240) = -4082 V.

Problem:
Find the maximum field strength at the insulator and the electric field distribution.

Solution:
To find the maximum field strength it is enough to simulate the electrostatic field at the moment of maximum voltage at the specific phase insulator. Phase A insulator maximum field simulation is presented (for phases B and C similar approach should be used).

Results:
Electric field strength distribution at the surfaces of the insulators is presented at the picture below.

See the bushing_insulator.pbm problem in the Examples folder.