
Custom LSR overmolded fitting for vacuum interrupters, made of industrial-grade liquid silicone rubber via injection molding. It has excellent insulation, high and low temperature resistance, arc aging resistance, closely fits the interrupter shell, and effectively improves the operation safety and service life of power equipment.
Material
Industrial LSR
Hardness
Shore A 60-80
Temperature
Certifications
Applications
-50°C ~ +200°C
Colors
Red, Black, Customizable
# Liquid Silicone Rubber Overmolded Insulation Protective Fitting for Vacuum Interrupter
The Liquid Silicone Rubber (LSR) Overmolded Insulation Protective Fitting for Vacuum Interrupter is a high-performance electrical insulation component designed to enhance the operational reliability and extend the service life of medium and high-voltage vacuum interrupters. Custom-engineered for precision overmolding directly onto vacuum interrupter ceramic or metal housings, this fitting eliminates air gaps between the interrupter surface and insulation layer, effectively suppressing partial discharge, preventing surface creepage, and resisting environmental degradation in harsh operating conditions.
Unlike traditional assembled epoxy or heat-shrink insulation sleeves, this LSR overmolded fitting forms a permanent, molecular-level bond with the interrupter substrate via a controlled injection molding process, delivering 360° seamless protection. It meets the strict insulation requirements of 10kV to 110kV power distribution and transmission systems, with core selling points including ultra-low partial discharge levels (<10pC at rated voltage), excellent high and low temperature resistance, and a 30-year expected service life under continuous electrical load. The product is tailored to fit standard and custom vacuum interrupter sizes for circuit breakers, reclosers, contactors, and load break switches.
The fitting is manufactured from high-purity, electrical-grade liquid silicone rubber formulated specifically for high-voltage insulation applications, with the following material characteristics:
The cured LSR insulation layer delivers consistent mechanical and environmental resistance across extreme operating conditions:
The overmolding process is optimized to ensure zero defects and strong adhesion to the vacuum interrupter substrate:
The seamless overmolding process eliminates micro-air gaps between the insulation layer and vacuum interrupter surface, a common cause of partial discharge in traditional assembled sleeves. With PD levels consistently below 10pC under rated operating voltage, the fitting avoids long-term insulation degradation caused by corona discharge, reducing the risk of interrupter failure by 85% compared to non-overmolded insulation solutions. This performance meets the strictest requirements of IEC 62271-100 for high-voltage switchgear.
Unlike epoxy resin insulation, which becomes brittle at temperatures below -20°C and softens above 120°C, the LSR fitting maintains stable mechanical and electrical properties across a -60°C to +200°C temperature range. It resists salt spray corrosion, UV radiation, acid rain, and fungal growth, making it suitable for outdoor installations in coastal, high-altitude, desert, and cold-climate regions. The material’s inherent hydrophobicity ensures that surface water forms discrete droplets rather than continuous films, preventing flashover even in heavy rain or high-humidity environments.
The overmolded fitting integrates creepage extension sheds, mounting positioning slots, and sealing interfaces into a single component, eliminating the need for separate gaskets, adhesive bonding, or sleeve assembly during switchgear production. The integrated structure reduces assembly time by 70% compared to traditional multi-part insulation solutions, while eliminating potential failure points caused by misaligned sleeves or degraded adhesive bonds over time.
The high elasticity of LSR (300% minimum elongation at break) allows the fitting to absorb mechanical stress caused by short-circuit current impact, switch operation vibration, and thermal expansion mismatch between the vacuum interrupter’s ceramic housing and metal switchgear frame. It will not crack or delaminate after 10,000 mechanical switching operations or 10g random vibration testing per IEC 60068-2-6, making it ideal for applications in high-vibration environments such as wind turbine switchgear and railway traction systems.
This LSR overmolded insulation protective fitting is widely used in medium and high-voltage electrical equipment where vacuum interrupters are deployed, including:
The fitting is custom-molded to match the specific dimensions of your vacuum interrupter, with standard models available for all mainstream interrupter sizes from 10kV to 110kV. When placing an order, provide the interrupter’s ceramic housing outer diameter, end flange dimensions, required creepage distance (minimum 20mm/kV for pollution level III areas, 25mm/kV for pollution level IV), and switchgear mounting interface dimensions to ensure a perfect fit.
All LSR overmolded insulation protective fittings undergo a strict multi-stage quality control process to ensure compliance with international and industry standards:
We offer a 5-year warranty against material defects and manufacturing faults, with long-term performance guarantees available for custom projects, supported by 15 years of LSR overmolding expertise in the electrical insulation industry. Our engineering team provides custom design support to optimize the fitting’s profile and material formulation for your specific application requirements.