Power cables are cables used to transmit or distribute high-power electric energy in power systems. With the rapid development of the petrochemical industry worldwide, plastic insulated power cables have become a common type of low-voltage power cables due to their simple manufacturing process, convenient construction and maintenance.
Power cables are cables used to transmit or distribute high-power electric energy in power systems. With the rapid development of the petrochemical industry worldwide, plastic insulated power cables have become a common type of 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 that defects such as bruises, scratches, crushing, and breakdown will occur. In order to ensure fixed-length production, reduce waste, 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 hot welding method uses an electric soldering iron with appropriate power to fuse the insulation with the heat of the soldering iron. 1.1 Low-voltage polyvinyl chloride insulated cable
Polyvinyl chloride material is a thermoplastic material. When used as a cable insulation layer repair, hot welding should be used. In order to ensure and enhance the electrical and mechanical properties of the repaired part, the repaired part is wrapped with a single layer of insulating tape, and the wrapping should be flat.
1.2 Low-voltage cross-linked polyethylene insulated cable
Cross-linked polyethylene material is a thermosetting material. After silane cross-linking, the insulating molecules are reticularly cured. Before the insulated wire core is boiled and cross-linked, the insulation damage is repaired by hot welding, and then the repaired part is wrapped with transparent tape to prevent the repaired part from falling off; after the insulated wire core is boiled and cross-linked, the insulation layer should be repaired by hot welding first, and then overlapped with high-voltage self-adhesive tape with a withstand voltage level of 35kV, and the high-voltage tape must be wrapped flat.
2 Heat shrink tube repair method
The heat shrink tube repair method is to put a heat shrink tube of suitable size on the defect point, heat shrink and tightly wrap the defect.
Regardless of whether the insulation material is thermoplastic polyvinyl chloride or thermosetting cross-linked polyethylene, the insulated wire core with a nominal cross-section of less than 10mm2 should be repaired with heat shrink tube. After the heat shrink tube repair is completed, it should be wrapped with insulating tape.
3 Comparison of repair methods
The hot welding repair method uses tools such as electric soldering irons to repair, and the insulation layer performance can reach the level of a complete cable, but the repair process is relatively complicated and requires the operator to have a high level of technology.
For wire cores with smaller cross-sections, it is difficult to ensure the quality of the repair if the hot welding method is used for repair. The heat shrink 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 product voltage 3.5kV/5min withstand voltage test must be carried out. The above repair method is only applicable to smaller insulation damage. For serious defects such as scratches, crushing, and bumps, repairs shall not be carried out to ensure product quality.