01-04 2026
Description of Aging Resistance Performance of Cold Shrink Cable Accessories
Aging resistance is one of the core performance indicators of cold shrink cable accessories, which directly determines their service life, operational reliability, and long-term stability in power systems. Cold shrink cable accessories are mainly made of high-performance elastomer materials represented by silicone rubber and ethylene-propylene-diene monomer (EPDM), and are designed to withstand long-term environmental erosion, electrical stress, thermal cycling, mechanical vibration, and chemical corrosion. Excellent aging resistance ensures that the accessories can maintain stable electrical insulation, mechanical elasticity, sealing performance, and stress control effects under outdoor, underground, humid, high-temperature, or polluted environments for 30 years or longer. This article systematically explains the aging mechanism, key material properties, anti-aging design, test standards, and application performance of cold shrink cable accessories.
1. Aging Mechanism of Cold Shrink Cable Accessories
The aging of cold shrink products mainly includes thermal aging, ultraviolet aging, ozone aging, humidity and water absorption aging, electrical aging, and chemical corrosion aging. These factors act individually or synergistically to cause molecular chain breakage, cross-linking, hardening, cracking, elasticity loss, surface chalking, or insulation degradation of the polymer material.
Thermal aging is the most common form. Long-term operating temperature cycling causes the rubber molecular structure to relax, degrade, or cross-link excessively, resulting in increased hardness, decreased elongation, and loss of sustained shrinkage force.
Ultraviolet aging mainly occurs in outdoor applications. UV radiation destroys the chemical bonds of polymer materials, leading to surface cracking, color fading, chalking, and reduced hydrophobicity.
Ozone aging is particularly harmful to rubber materials. Ozone reacts with unsaturated molecular chains under mechanical stress, causing ozone cracking and significantly reducing mechanical strength.
Moisture and water absorption aging easily occurs in underground tunnels, direct burial, and wet environments. Water intrusion destroys the interface between the accessory and the cable, reduces insulation resistance, and accelerates hydrolysis and degradation of the material.
Electrical aging comes from long-term electric field intensity, partial discharge, and impulse voltage, leading to insulation treeing, carbonization, and even breakdown.
Chemical corrosion aging is caused by acid, alkali, salt fog, oil, and industrial waste gas, which erode the material surface and reduce sealing and insulation performance.
2. Material Basis of Aging Resistance of Cold Shrink Cable Accessories
High-performance raw materials are the prerequisite for excellent aging resistance.
Liquid silicone rubber (LSR) is the most widely used high-grade material. It has a stable Si-O-Si main chain structure, with bond energy much higher than that of C-C bonds, giving it outstanding heat resistance, UV resistance, and ozone resistance. It can work for a long time in the range of -60°C to 200°C, and maintains good elasticity and hydrophobicity after long-term aging. Silicone rubber naturally repels water and has excellent self-recovery ability of hydrophobicity, which can effectively inhibit moisture intrusion and surface flashover.
EPDM rubber has excellent heat aging, ozone aging, and water resistance. Its saturated molecular structure makes it highly resistant to ozone and weathering. It has good mechanical strength and tear resistance, suitable for buried and industrial environments.
High-quality cold shrink products use imported raw materials with precise formula systems, including anti-aging agents, anti-ozone agents, UV stabilizers, thermal stabilizers, and processing aids. These additives can capture free radicals, block photo-thermal degradation, delay oxidation reactions, and greatly improve comprehensive aging resistance.
In contrast, recycled rubber or low-quality materials lack effective anti-aging protection systems. They will quickly harden, crack, lose elasticity, and fail within a few years, bringing great hidden dangers to cable lines.
3. Structural Design for Improving Aging Resistance
In addition to material optimization, structural design also significantly enhances aging resistance.
The integral injection-molded stress cone avoids layered debonding and interface aging, ensuring uniform electric field distribution and reducing electrical aging risks.
The multi-layer composite insulation and shielding structure improves electric field distribution, reduces partial discharge, and slows down insulation degradation.
The high-rebound integral body structure maintains long-term radial pressure on the cable, preventing interface gaps caused by material shrinkage or thermal expansion and contraction, thus blocking moisture and dust.
Outdoor cold shrink terminals are equipped with integral umbrella skirts, which increase creepage distance, improve pollution flashover resistance, reduce UV and rain erosion, and extend outdoor service life.
The fully sealed waterproof structure of intermediate joints prevents water penetration, effectively slowing down hydrolysis aging and insulation deterioration in underground and waterlogged environments.
4. Test Standards and Evaluation Indicators of Aging Resistance
The aging resistance of cold shrink cable accessories is strictly verified according to international and national standards such as IEC 60502, GB/T 9327, GB/T 2951, etc.
Thermal aging test: Samples are placed in a high-temperature aging oven for 168 hours, 500 hours, or even 1000 hours at 135°C or 150°C. After aging, tensile strength, elongation at break, hardness change, and electrical performance are tested. Qualified products show elongation retention rate higher than 70% and no cracking, chalking, or bonding.
Ozone aging test: Under a certain ozone concentration and temperature, with static or dynamic stress applied for hundreds of hours, the surface should have no ozone cracks.
UV weathering test: Using xenon lamp or UV lamp accelerated radiation for thousands of hours, the surface has no cracking, chalking, or obvious performance degradation.
Heat shrinkage cycle test: Simulating long-term temperature rise and fall operation to verify dimensional stability and interface bonding reliability.
Water absorption and immersion test: After long-term immersion, the insulation resistance change rate and breakdown voltage performance are evaluated.
Electrical aging test: Including long-term voltage endurance test, partial discharge test, and lightning impulse cycle test to verify insulation stability.
Products that pass these tests can maintain stable performance for more than 30 years under normal operating conditions.
5. Long-Term Performance Performance After Aging
After long-term natural or accelerated aging, high-quality cold shrink cable accessories still maintain the following key properties:
Stable mechanical elasticity and shrinkage force: No permanent deformation, no loosening, and can maintain effective radial pressure to ensure cable clamping and interface sealing.
Excellent electrical insulation performance: Insulation resistance, breakdown strength, and partial discharge performance meet standard requirements, no insulation treeing or breakdown.
Reliable sealing and hydrophobicity: No water seepage, no moisture absorption, and the surface maintains good hydrophobicity to prevent pollution flashover.
Good environmental adaptability: No hardening, cracking, chalking, or bonding, adapting to high and low temperature cycles, UV radiation, ozone, humidity, and chemical corrosion.
In contrast, inferior products will rapidly age, leading to interface discharge, overheating, water ingress, insulation breakdown, and even power outages.
6. Conclusion
Aging resistance is a comprehensive reflection of material formula, manufacturing process, and structural design of cold shrink cable accessories. High-performance silicone rubber or EPDM materials, efficient anti-aging systems, precise injection molding processes, and optimized structural design jointly endow products with excellent resistance to heat, ozone, UV, humidity, electricity, and chemical corrosion. Strict type tests and long-term operational practice have proven that qualified cold shrink cable accessories can maintain stable electrical and mechanical properties for more than 30 years under various harsh environments.
In engineering applications, selecting cold shrink cable accessories with excellent aging resistance can significantly reduce line faults, lower maintenance costs, extend the replacement cycle, and improve the safety and reliability of power supply systems. For purchasers, designers, and construction units, aging resistance should be one of the core indicators for evaluating product quality, so as to ensure the long-term stable operation of cable lines.
