How do silicone sealing gaskets, with their excellent electrical insulation and arc resistance, meet the safety sealing requirements of high-voltage electrical equipment?
Publish Time: 2026-02-17
In modern high-voltage electrical systems, such as smart grid equipment, new energy vehicle control units, photovoltaic inverters, and rail transit traction systems, the requirements for sealing materials far exceed the traditional scope of waterproofing and dustproofing. They must maintain structural integrity and electrical safety under harsh conditions such as high voltage, strong electric fields, partial discharge, and even sudden arcing. Silicone sealing gaskets, with their superior electrical insulation properties, excellent arc resistance, and stable physicochemical properties, have become the ideal choice for achieving "safety sealing" in high-voltage electrical equipment.1. High Dielectric Strength and Low Conductivity: Building a Reliable Insulation BarrierThe silicone molecular structure, composed of a stable Si–O backbone and nonpolar methyl side chains, endows it with extremely low electrical conductivity and extremely high volume resistivity. This means that it can withstand thousands of volts without breakdown even at a thickness of millimeters. This characteristic allows silicone sealing gaskets to form an effective electrical isolation layer between high-voltage joints, end caps, or housing flanges, effectively blocking leakage current paths between components at different potentials. This prevents short circuits, flashovers, or equipment damage caused by insulation failure, providing fundamental safety assurance for the system.2. Self-protective arc-resistant mechanism: Resisting electrical spark erosionDuring switching operations or fault conditions, instantaneous arcs may occur inside high-voltage equipment, reaching temperatures exceeding 3000℃, sufficient to carbonize most organic materials and form conductive paths. However, under the high temperature of the arc, the surface of silicone rapidly oxidizes to form a dense, hard, and highly insulating silica ceramic film. This "self-generated protective layer" not only isolates oxygen and inhibits further combustion but also effectively prevents the arc from spreading into the material, avoiding the formation of continuous conductive paths. According to ASTM D495 standard testing, high-quality silicone can withstand arcs for over 180 seconds, significantly better than traditional materials such as EPDM and neoprene rubber, greatly improving the fault tolerance of equipment under abnormal operating conditions.3. Wide Temperature Range Stability and Anti-aging Performance: Ensuring Long-Term ReliabilityHigh-voltage electrical equipment often faces extreme temperature cycling and long-term electric field stress. Silicone, thanks to the high bond energy of the Si–O bonds, maintains excellent elasticity and compression set over a wide temperature range. Even after long-term use in ozone, ultraviolet, or humid environments, it is not prone to hardening, cracking, or powdering. This stability ensures a consistently tight seal, preventing the intrusion of moisture, salt spray, or conductive dust, thus avoiding surface discharge or insulation degradation caused by contaminant accumulation and achieving safe operation throughout its entire lifecycle.4. Engineering Adaptability and System Integration: From Materials to Safety SolutionsIn practical applications, silicone sealing gaskets can be molded or punched into complex cross-sectional shapes to precisely match the mounting grooves of high-voltage housings, achieving a "zero-gap" seal. Its flexibility can compensate for minor deformations or assembly errors in metal components, while also exhibiting good interfacial compatibility with commonly used electrical materials such as epoxy resin, ceramics, and aluminum alloys. Some high-end products also achieve UL 94 V-0 flame retardant standards by adding flame-retardant fillers such as aluminum hydroxide, ensuring no release of toxic gases in extreme conditions such as fires, thus balancing functional safety and personal safety.In summary, silicone sealing gaskets are not only elastic seals but also multifunctional components in high-voltage electrical systems, integrating insulation, protection, weather resistance, and safety. Their unique electrical insulation and arc resistance enable them to build an invisible yet crucial safety barrier while ensuring efficient equipment operation, providing solid support for the reliable development of smart power and green energy infrastructure.
