On-site repair Guide for Damaged Cable Sheaths

- GUANGSHUNCABLE -

The construction environment for cables is often very "bad" : it may be in newly-built power plants, outdoor railways, or in cable trays or tunnels. However, the commonly used plastic welding gun for repair requires 220V AC power. But in field projects, power supply is often lacking. Even if there is, the cable laying location is random and power supply is troublesome.

The solution is crucial: The construction unit must prepare a small generator for the field and select a high-quality plastic welding torch - the nozzle has a large heating area and can heat up quickly, which can improve efficiency.

In addition, complex terrains such as mountainous areas will make the repair more difficult. In fact, reducing damage is more important than repairing: equipping sufficient construction personnel and using professional laying equipment for regular wiring to lower the probability of sheath damage from the source.

A. Don't rush to repair the damaged cable! The first step is to confirm whether the interior is damaged. If the interior is already damaged, a repair cover alone is of little significance. Moreover, repairs should be carried out promptly, especially during the rainy season in the south. Delaying may allow moisture to seep in, causing the conductors to turn black and the entire cable to be scrapped.

The laid cables should also be properly inspected, maintained and stored to prevent their lifespan from being shortened due to external factors before being powered on.

B. Complete tools and materials for easier repair: For on-site repair, sufficient tools and materials must be prepared. Essential items include plastic welding torches, high-voltage insulating tape, waterproof tape, and sealing materials such as the skin peeled off from the end of the cable.

C. Different materials of cables require different repair methods:

Thermosetting materials such as cross-linked polyethylene cannot be melted and reused, and can only be repaired with high-voltage insulating tape series.

Thermoplastic materials such as polyethylene and polyvinyl chloride can be melted at high temperatures and reused. On-site materials are available. By cutting the stripped corner sheath materials into thin strips, the insulation and sheath of low-voltage cables can be repaired, and the quality can meet the normal usage requirements.

Low-voltage cables: Only when the damage is minor, with only the insulation and sheath damaged and other structures intact, can they be repaired.

Medium and high voltage cables: More stringent requirements. When laying, handle with care. If the sheath is damaged, the internal insulation may have been compromised. There was once a case where a cable with multiple damaged outer sheaths was returned to the factory for testing, resulting in excessive partial discharge and breakdown. Therefore, when the sheath of medium-voltage power cables is damaged, it is best to cut it to make an intermediate joint or replace the cable to avoid leaving hidden dangers.

Some projects use long-length single-core cables to reduce intermediate joints, which can be laid over long distances, in complex terrains, and with insufficient personnel and equipment, making it more likely for the sheath to be damaged. If ordinary tape is used to wrap it casually at this time, it is extremely irresponsible and may cause insulation breakdown during the completion test or later operation.

Although the technical requirements for cable sheath repair are not high, it is related to the safe operation and service life of the cable. Only by making thorough preparations in advance, choosing the right methods and treating different cables differently can the repair be completed efficiently and with high quality on site, ensuring the "healthy" operation of the cables.