Requirements for the Installation of Heat-Shrinkable Power Cable Accessories

　　Heat-shrinkable power cable accessories are characterized by their compact size, reliable performance, strong adaptability, and ease of installation. They are suitable for indoor and outdoor terminations and intermediate connections of power cables.

1. The allowable ambient temperature range for using heat-shrinkable power cable accessories is –40°C to +70°C.
2. The installation of heat-shrinkable cable accessories must be completed in one continuous operation to avoid moisture ingress. For 10KV and below cables, the heat-shrinkable termination should be completed within four hours.
3. During the fabrication of cable terminations and intermediate joints, the following parts must be kept dry and clean:
4. The hands of the construction personnel should always remain clean.
5. Before making cable terminations, all necessary tools should be prepared, and the construction personnel should be familiar with the use, inspection, and precautions of various tools.
6. The construction site should have sufficient lighting, and the lighting equipment must comply with safety regulations.
7. When there are live electrical equipment nearby, appropriate safety measures should be taken.
8. The construction site must comply with fire safety regulations. Fire extinguishing equipment should be available on-site, and precautions must be taken to prevent fire and explosions when using blowtorches.
9. It is recommended to use a propane torch as the heating tool. The flame should be yellow with moderate temperature and a large heating area. If using a gasoline torch with a high-temperature blue flame, maintain an appropriate distance from the material, control the temperature, and avoid scorching.
10. All heat-shrinkable components are made of polymer materials through special processes. The material begins to shrink at 110°C to 120°C, with a shrinkage rate of over 50%. The material will not be affected by short-term exposure to 140°C, but prolonged local overheating can damage or even burn the material, affecting its performance.
11. When starting to shrink the components, the flame should slowly approach the material and move around it to ensure uniform radial shrinkage. Then, slowly extend the flame in the direction of shrinkage to preheat the material, which helps achieve uniform shrinkage. Follow the recommended starting point and direction of shrinkage in the installation procedure. Shrinking from the bottom up helps eliminate gas and enhances sealing.
12. To ensure a tight bond and strong adhesion between the heat-shrinkable tubing and the wrapped material, preheat the wrapped area and the adhesive sealing section before sliding on each layer of tubing. Then, clean with a cleaning agent to remove flame soot deposits and ensure good contact between layers.
13. Do not arbitrarily cut heat-shrinkable tubing.
14. The areas where heat-shrinkable accessories come into contact with metal components (e.g., lead sheath, terminals) should be carefully roughened and cleaned with a cleaning agent.
15. Construction should not be carried out in rainy or foggy weather. If the cable is found to be wet or damp, remedial measures should be taken.
16. During construction, damage to the cable sheath and insulation is strictly prohibited.
17. The cable should not be moved until the heat-shrinkable intermediate joint has completely cooled down.

Causes of Cable Termination Overheating:
　　Poor quality in the fabrication of cable intermediate joints can lead to overheating. Specific situations include:
1. Loose crimping of the cable termination's crimp connector, resulting in excessive contact resistance and overheating during operation.
2. Asymmetric geometric positioning of the three-phase crimp connectors, creating an asymmetric electric field that accelerates insulation aging.
3. Residual air bubbles in the insulation filler and heat-shrinkable tubing generated during fabrication, leading to partial discharge under the electric field and eventual insulation breakdown.
4. Incomplete removal of metal burrs after crimping during the fabrication of cable terminations, causing corona discharge during operation and eventual insulation breakdown.