LSR Material Selection and Manufacturing for Cable Accessories

Cable accessories (cold-shrink/hot-shrink terminations, joints) are critical components in power transmission systems. LSR has become the core insulation material due to excellent electrical insulation, weather resistance, and processing precision.

1. Cable Accessory Material Requirements

1.1 Electrical Requirements

• Volume resistivity: greater than 1x10^15 ohm-cm
• Dielectric strength: greater than 20 kV/mm
• Dissipation factor: less than 3x10^-3 (50Hz)
• Relative permittivity: 2.8-3.5

1.2 Mechanical Requirements

• Tensile strength: greater than 6 MPa
• Elongation at break: greater than 200%
• Tear strength: greater than 15 kN/m
• Hardness: 40-60 Shore A

1.3 Environmental Requirements

• UV aging resistance, Ozone resistance
• Temperature range: -50 to 150 degrees
• Flame retardancy: UL94 V-0/V-1

2. LSR Material Selection

2.1 Insulation-Grade LSR

For cable termination and joint main insulation, volume resistivity greater than 1x10^15, typical hardness 40-50 Shore A

2.2 Stress Control Grade LSR

For stress cones and stress control layers, high permittivity (8-15), non-linear resistance characteristics

2.3 Semiconductive Grade LSR

For shielding layers, volume resistivity 10^2 to 10^5 ohm-cm, carbon black filled

2.4 Flame-Retardant Grade LSR

For outdoor terminations, UL94 V-0 rating, aluminum hydroxide/platinum catalyst system

3. Manufacturing Process

3.1 Cold-Shrink Termination

1. LSR injection molding of insulation tube
2. Inner wall silicone grease application
3. Expansion onto support tube (ratio 2-4x)
4. Quality inspection (dimensions, appearance, electrical)

3.2 Joint Production

1. Injection mold main insulation body
2. Injection mold stress cone
3. Assemble shielding layer and stress cone
4. Complete electrical testing

4. Mold and Process Control

• Wall thickness uniformity: difference less than 0.3mm
• Concentricity: less than 0.2mm
• Surface roughness: Ra less than 0.4 micrometers
• Injection pressure: 40-80 MPa
• Mold temperature: 160-190 degrees
• Cure time: 40-90 seconds

5. Quality Inspection

• Routine: Appearance, dimensions, hardness
• Electrical: Power frequency withstand, partial discharge (less than 5pC)
• Type tests: Load cycling, salt spray, UV aging, water vapor permeation

Conclusion

LSR applications in cable accessories continue to expand. Correct material selection and strict process control are essential for long-term reliability. With grid upgrades and renewable energy development, high-performance LSR cable accessories face growing market opportunities.