Nanodielectric HVDC Cable Insulation — Space-Charge Trapping

HVDC Cable Insulation

Applied DC voltage 300 kV

Nanofiller trap density 15%

Simulation speed 3×

Show field vectors

Live Readouts

Field enhancement factor1.00×

Trapped charge fraction0%

Simulated stress time0 h

How it works

Under sustained DC stress, charge carriers injected from the inner conductor drift through the polymer insulation and pile up as space charge. That accumulated charge distorts the electric field away from its clean geometric shape — sometimes enhancing it far from the electrode where the insulation never expected the stress, a leading cause of electrical treeing and premature HVDC cable failure.

Cylindrical Poisson:  (1/r) d/dr( r dφ/dr ) = -ρ(r) / ε
Continuity + traps:   ∂n_free/∂t = -(1/r)∂(r·μE·n_free)/∂r + S_inj - k_trap·n_free
                       ∂n_trap/∂t = k_trap·n_free
Field enhancement:    FEF = max|E(r)| / [V / (r₁·ln(r₂/r₁))]

The simulator solves Poisson's equation on 24 concentric shells between the conductor (r₁) and the grounded sheath (r₂) every physics step, using the resulting field to drive carrier injection and drift, then a fraction of the free carriers becomes permanently trapped each step.

Nanofiller trap density — real HVDC nanocomposite insulation blends in MgO or Al₂O₃ nanoparticles, whose interfaces create deep (~1 eV) trap states. At 0% the polymer is "plain" — injected charge drifts freely deep into the bulk and the field profile drifts far from its safe geometric shape. Turned up, carriers get immobilised right where they're injected, forming a thin compensating layer that keeps the bulk field close to ideal.
Applied DC voltage — sets the boundary condition φ(r₁)=V; higher voltage drives faster injection and a higher baseline field.
Field enhancement factor — the ratio of the true peak field (from the Poisson solve) to the field a pristine, charge-free coaxial insulator would have. Values well above 1× flag a real breakdown risk.

Shell colour encodes charge: grey is neutral insulation, teal is mobile free charge, amber is charge a nanofiller trap has pinned in place.

Neutral insulation Mobile free charge Trapped charge

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