From Insulation to Conduction: How to Resolve the Performance Paradox in Composite Post Insulator Housing Materials?

As a composite post insulator supplier, I’ll clarify the electrical conductivity characteristics of housing materials—critical for insulation performance.

Core Electrical Properties

Ultra-Low Bulk Conductivity

Housing materials (typically silicone rubber) act as insulators with volume resistivity of 10¹²–10¹⁵ Ω·cm.

Prevents current leakage through the material body, avoiding power losses or thermal runaway.

Surface Resistivity Maintenance

Surface resistivity prevents tracking currents along the insulator.

Hydrophobicity repels water, disrupting conductive pollution layers (e.g., industrial deposits, coastal salt).

Maintains >10¹¹ Ω surface resistance even in wet conditions.

Dielectric Constant Optimization

Low relative permittivity (εᵣ ≈ 2.8–3.5) minimizes:

Capacitive coupling between conductors

Energy storage in the material

Reduces dielectric losses and partial discharge risks.

Performance in Applications

Transmission Lines (e.g., 126kV models):

High volume resistivity withstands electrical stresses at extreme altitudes.

Distribution Systems (e.g., 66kV units):

Low εᵣ enables compact designs for pole-mounted transformers.

Material Science Insights

Product-Specific Validation

Our 126kV and 69kV Line Post Insulators undergo:

• 1,000-hour salt fog tests (IEC 62217)
• Hydrophobicity class HC1–HC2 verification
• Dielectric loss tangent measurements (<0.2%)

Conclusion

The synergy of high volume resistivity, sustained surface hydrophobicity, and optimized dielectric constant ensures reliable insulation.

These material properties enable composite post insulators to outperform porcelain/glass equivalents in harsh environments.

References

• IEEE Std 1462-2002 (Polymer Insulator Applications)
• IEC 61109 (Composite Insulator Test Criteria)
• Silicone Rubber for High-Voltage Insulators(CIGRE TB 442)
• Kumagai, S. Aging Mechanisms in Polymer Insulators