Discuss low-voltage plastic insulated power cable insulation damage repair methods

Power cables are cables used to transmit or distribute high-power electrical energy in power systems
.
With the great development of the petrochemical industry in the world, plastic insulated power cables have become an important variety
in low-voltage power cables due to their simple manufacturing process, convenient construction and maintenance.
However, in the process of plastic insulation extrusion, it is inevitable to produce defective points such as bumps, scratches, crushes, and breakdowns, in order to ensure fixed-length production, reduce scrap, and ensure that the electrical performance of the finished cable meets the standard requirements, it is necessary to find a suitable insulation damage repair method
.

1 Hot welding repair method

The thermal welding method uses a soldering iron of suitable power to heat the insulation with
a soldering iron.

1.
1 Low-voltage PVC insulated cable

PVC material is a thermoplastic material, and should be used in the form
of heat welding when repairing the damage of the cable insulation layer.
In order to ensure and strengthen the electrical and mechanical properties of the repair, the insulation tape is used to carry out a single-layer overlapping wrapping of the repair, and the wrapping should be flat
.

1.
2 Low-voltage XLPE insulated cable

Cross-linked polyethylene materials are thermosetting materials, and the insulating molecules are solidified
in a network after silane crosslinking.
Before the crosslinking process of boiling water of the insulated core, the insulation damage repair is repaired by hot welding, and then the repair is wrapped with transparent tape to prevent the repair from falling off; After the crosslinking process of boiling water of the insulated core, the damage of the insulation layer should be repaired by hot welding method first, and then overlapped with high-pressure self-adhesive tape with a voltage resistance grade of 35kV, and ensure that the high-voltage tape winding must be flat
.

2 Heat shrinkable tube repair method

The heat shrinkable tube repair method is to put the heat shrinkable tube of suitable size at the defect point, heat shrink and tightly wrap the
defect.

Whether the insulation material is thermoplastic polyvinyl chloride or thermosetting cross-linked polyethylene, the insulating core with a nominal cross-section of less than 10mm2 should be repaired with a heat shrinkable tube, and after the heat shrinkable tube is repaired, it is wound with insulating tape
.

3 Comparison of patching methods

The thermal welding repair method is repaired by tools such as electric soldering iron, and the performance of the insulation layer can reach the level of the complete cable, but the repair process is relatively complex and requires the operator to have a high technical level
.
For wire cores with small cross-sections, if the hot welding method is used to repair, it is not easy to ensure the repair quality, and the heat shrinkable tube repair method
should be used.

In order to ensure that the electrical performance of the repaired insulated wire core meets the standard requirements, the insulation layer spark test and the finished voltage 3.
5kV/5min withstand voltage test
must be carried out.
The above repair methods are only suitable for small range of insulation damage, and for serious defects such as scratches, crushes, and bumps, in order to ensure product quality, it must not be repaired
.