Cable insulation electric stress
Electric field strength distribution in the insulation of a three-phase power cable with sector-shaped conductors, including the conductor geometry and grounded metal screen.
How can the electric field strength distribution be computed in the insulation of a three-phase cable with sector-shaped conductors?
Treat the multi-layer paper insulation as an equivalent homogeneous dielectric, and solve the electrostatic problem at the instant when the phase voltage is at its maximum.
- High-voltage power cables
- Cable insulation layers
- Cable dielectric structures
Simulation Problem
- Problem Type
- Plane-parallel Electrostatics
- Geometry
- Three-phase cable with sector-shaped conductors, outer diameter Ø44 mm, including insulation and screen layers.
- Given
- Filler relative permittivity ε = 2.8
- Insulation relative permittivity ε = 4
- Line voltage 10 kV, screen potential 0 V
- Task
- Compute the electric field strength distribution in the insulation.
- Solution
The oil-impregnated paper insulation consists of many layers with different permittivities; to simplify the calculation, the multi-layer structure is replaced with a homogeneous insulation.
- Results
The figure shows the electric field distribution across the cable cross-section at the instant when the potential of phase A (the upper conductor) reaches its maximum.
This field pattern is typical of three-phase cables with sector-shaped conductors, regardless of insulation type. Regions 1-3 are characteristic regions of the insulation, with region 2 having the highest field strength.
Reference: Dmitry Arsenyev, Simon Dubitsky, Dmitry Kiesewetter, Victor Malyugin. Numerical Simulation and Calculation of Resistance of Laminated Paper-Impregnated Insulation of Power Cables. Energies 15, no. 19 (2022): 7403.
