Hello! As a supplier of 20kV Composite Post Insulators, I’m often asked about their flame resistance. Let’s break down how these units perform under fire conditions.
Material Composition and Flame Resistance
A 20kV Composite Post Insulator consists of:
Fiberglass core: High mechanical strength with a melting point exceeding 600°C, providing structural integrity during thermal exposure.
Silicone rubber housing: Inherently flame-retardant due to:
High oxygen index (typically >28%), requiring elevated oxygen concentration to sustain combustion.
Char formation: When exposed to flames, it generates a protective char layer that shields the core and halts fire spread.
Compliance with Fire Safety Standards
These insulators typically meet UL94 V-0 certification, indicating:
Self-extinguishing within 10 seconds after flame removal.
Zero flaming drips during vertical burning tests.
Additional validation often includes glow-wire ignition testing (GWIT >775°C), simulating electrical fault-induced overheating to ensure no ignition occurs.
Real-World Performance Factors
Environmental conditions significantly impact flame resistance:
Contamination accumulation (e.g., dust, pollutants): Can create conductive paths, leading to arcing and localized heating. Regular cleaning mitigates this risk.
Long-term degradation: UV exposure or extreme temperatures may reduce silicone rubber’s flame retardancy. Our formulations include UV stabilizers and age inhibitors to maintain performance over decades.
Comparison with Other Insulator Types
Porcelain insulators: Non-combustible but brittle; shatter under mechanical stress or thermal shock, posing fragmentation hazards during fires.
Composite insulators (10kV/35kV): Share similar flame-retardant mechanisms but differ in design. Higher-voltage models (e.g., 35kV) incorporate thicker silicone layers for enhanced arc resistance.
Design Enhancements for Fire Safety
UL94 V-0 compliant silicone: Prevents flame propagation and drip ignition.
Fiberglass core treatment: Fire-resistant resins boost thermal stability up to 300°C without compromising dielectric strength.
Hydrophobic recovery: Post-fire, silicone surfaces restore water repellency, minimizing contamination-related fire risks.
Applications and Selection Guidance
Ideal for:
Substations in wildfire-prone regions.
Industrial zones with high pollution levels.
When selecting insulators:
Prioritize UL94 V-0 or IEC 60695 GWIT-certified units.
Verify third-party test reports for flame resistance and tracking resistance.
References
· UL 94-1985: Test Standard for Flammability of Plastic Materials (V-0 classification criteria).
· IEC 60695-2-12: Glow-Wire Ignition Temperature (GWIT) Test Methodology.
· Silicone Rubber for High-Voltage Insulators: Aging and Fire Performance (Journal of Electrical Engineering, 2023).
· Thermal Stability of Fiberglass-Reinforced Composites in Fire Conditions (Materials Science Reports, 2024).
