• Zhejiang Zuoke Electric Technology Co., Ltd

Key Points and Precautions for Purchasing Cold Shrink Cable Accessories

1. Basic Parameter Matching: Voltage Rating and Cable Size

• Voltage Grade Confirmation

  Common voltage levels include 1–10kV (Um=12kV), 35kV (Um=40.5kV), and 110kV. Purchasers must select accessories with rated voltage not lower than the cable’s operating voltage. For 10kV systems, choose 10kV cold shrink terminals/joints; for 35kV lines, use 35kV full-set accessories. Using low-voltage products on high-voltage cables causes insulation breakdown, while over-specifying high-voltage models increases unnecessary costs.
• Cable Cross-Section Range

  Cold shrink accessories have applicable cross-section ranges (e.g., 25–50mm², 70–120mm², 150–300mm²). Confirm the cable’s nominal cross-section (single-core or three-core) and select accessories with matching or compatible ranges. Avoid forced installation of undersized accessories (causing excessive tension and rupture) or oversized products (resulting in insufficient radial pressure, poor sealing, and electrical gaps).
• Core Type and Structure

  Distinguish between single-core and three-core cables. Three-core cables require cold shrink branch sleeves and integrated three-core terminals; single-core applications need separate single-core accessories. Also confirm cable insulation material (XLPE/EPR), outer sheath type (PVC/PE), and armored/non-armored structure to select matching grounding and sealing components.

2. Material Quality and Performance: Core of Product Reliability

• Main Body Material

  Premium cold shrink products use silicone rubber (SiR) or ethylene-propylene-diene monomer (EPDM).

• Silicone rubber: Excellent high-voltage insulation, heat resistance (–60°C to 200°C), anti-aging, and hydrophobic properties; ideal for outdoor and high-altitude areas.

• EPDM rubber: Superior mechanical strength, tear resistance, oil resistance, and cost-effectiveness; suitable for indoor, tunnel, and direct-buried scenarios.

  Avoid low-grade recycled rubber products—they exhibit poor elasticity, rapid aging, and severe shrinkage after 1–2 years, leading to failure.

• Expansion Ratio and Elasticity

  Qualified cold shrink joints/terminals require expansion ratio ≥100% (ideally 200–300%). Higher expansion ensures sustained radial pressure on cables, preventing interface discharge and water intrusion. Check elasticity: premium products rebound quickly without permanent deformation after compression.
• Stress Control System

  High-quality accessories integrate integral stress cones (injection-molded with insulation, no gaps) for uniform electric field distribution and partial discharge suppression. Inferior products use separate stress tapes or poorly bonded cones, causing electric field distortion and breakdown risks.
• Sealing and Waterproofing

  Middle joints need three-layer sealing (core insulation, inner sheath, outer sheath). Outdoor terminals require integrated waterproof skirts and reliable bottom sealing. Verify IP68-rated waterproof performance for direct-buried and submerged applications.

3. Application Environment Adaptability: Site-Specific Selection

• Temperature Environment

• High cold (≤–30°C): Select low-temperature-resistant silicone rubber models to avoid hardening and cracking.

• High heat (≥40°C): Choose heat-stable materials with long-term heat resistance ≥90°C and short-circuit tolerance (250°C for ≤5s)哈尔滨政务服务网.

• Humidity and Water Conditions

• Direct-buried/waterproof: Select fully sealed joints with metal or high-strength plastic shells.

• Coastal/salt-fog areas: Use salt-spray-resistant EPDM or anti-corrosion coated accessories.

• Special Environments

• High altitude (>1000m): Select altitude-derated products to compensate for reduced dielectric strength.

• Polluted/chemical zones: Choose anti-corrosion, anti-ultraviolet, and anti-ozone models.

• Flammable/explosive sites (mines, petrochemical): Use flame-retardant (FR) and fire-resistant (FR) cold shrink accessories with fire barriers哈尔滨政务服务网.

4. Product Type and Structure: Terminals vs. Joints

• Cold Shrink Terminals

• Indoor terminals: Compact structure, no need for extra weather protection.

• Outdoor terminals: Equipped with umbrella skirts to enhance pollution and water resistance.

  Ensure matching with cable entry methods (cable trench, tunnel, overhead).

• Cold Shrink Middle Joints

• Straight joints: For cable extension.

• Insulated joints: For metal shield isolation.

• Transition joints: For connecting different cross-sections or insulation types.

  Choose bullet-type or molded-type joints for high mechanical strength and anti-tension performance.

• Accessory Completeness

  A full set should include: main body (terminal/joint), stress control tube, semi-conductive tape, insulating tape, copper grounding wire, heat-shrink closure, fixtures, and installation manual. Incomplete kits cause on-site delays and quality risks.

5. Qualification Certification and Quality Control

• Necessary Certifications

• National type test report (GB/T 9327, IEC 60502).

• Production license and ISO 9001 system certification.

• Third-party quality inspection (CMA/CNAS marked).

• For grid projects: access to national grid supplier lists.

• Key Test Items

  Verify reports for: AC/DC withstand voltage, partial discharge (<10pC), insulation resistance, thermal stability, aging resistance, waterproof and sealing performance. Reject products without valid test data.
• Appearance and Craft Inspection

• Smooth surface, no bubbles, cracks, or impurities.

• Uniform wall thickness, consistent elasticity.

• Clear marking: voltage, cross-section, manufacturer, production date, batch number.

6. Supplier and After-Sales: Long-Term Operation Guarantee

• Supplier Strength

  Choose professional manufacturers with ≥5 years of experience, mature production, and strict quality control. Avoid unknown small workshops with unstable quality.
• After-Sales Support

• Warranty: ≥15 years for high-quality products, ≥10 years for standard models.

• Technical support: on-site guidance, installation training, troubleshooting.

• Supply stability: ensure spare parts availability for 10+ years.

• Price vs. Value

  Reject overly low-cost products (below 50% of market average)—they use inferior materials and cut corners. Prioritize cost-performance over initial price.

7. Common Purchasing Mistakes and Avoidance

• Mismatched voltage/cross-section: Causes breakdown or loose fit.

• Ignoring environment: Selecting indoor models outdoors leads to premature failure.

• Incomplete kits: Missing grounding/tape causes rework and safety hazards.

• No certification: Risk of grid rejection and operational accidents.

• Blind price pursuit: Low-cost products lead to high long-term maintenance costs.

Summary