Cable thermal breakdown
QuickField simulation example
The insulation in a DC cable is subjected to both thermal and electric stress at the same time. Defects in insulation may cause a local overheating due to leakage currents. Calculate the electric current in the faulty insulation with a small defective area.
Problem Type
A plane-parallel problem of DC conduction.
Geometry
Given
Conductor potential U = 10 kV, shield potential U = 0 V.
Insulation temperature T = 80 °C. Hot spot temperatureTmax = 120 °C.
Electric conductivity of insulation σ depends on temperature, as shown on the plot below.
Task
Calculate the electric current in the insulation.
Solution
The model depth is taken to be 10 cm, which corresponds to the defect region axial length.
Results
| Total leakage current, I | |
| Normal | 1.278e-8 A |
| With defect | 1.282e-8 A |
Current density distribution in the insulation close to the thermal defect.
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