Knowledge of Power Cable Structure
The power cable generally consists of a wire core, an insulating layer and a protective layer. The wire core is used for conducting electricity, and the insulating layer is used to insulate the core conductor from the protective layer to prevent leakage of electricity; the protective layer is used to prevent the cable insulation from being damaged and damp, and to prevent the outflow of the liquid insulation (insulating oil).
Cable core has two kinds of copper core and aluminum core. Wire core section shape has circular, semi-circular and fan-shaped three kinds. Three-core and four-core low-voltage cable multi-purpose fan-shaped core. According to the variety and specifications of the cable, the wire core can be made into a single-stranded entity or a twisted wire core. The twisted wire core is made up of round single wire and forming single wire.
1. Plastic insulated cables are commonly include PVC, polyethylene and cross-linked polyethylene, etc.
1) PVC insulated cables
The installation process is simple, the installation maintenance is convenient, can adapt to the high drop difference laying, has the non-combustibility, the working temperature has the obvious influence to its mechanical performance. Generally used in 6kv and the following systems.
2) PE insulated cable
It is suitable for high drop laying, good process performance, easy to process, but easy to delay and burn, heat easy to deform, prone to stress cracking. Use less.
3) XLPE cable
The XLPE cable has high allowable temperature, so it has high allowable current and good heat resistance. It is suitable for laying with high drop, easy installation and maintenance, corona resistance and poor performance of free discharge. Cross-linked polyethylene cable has been more and more widely used in various voltages.
2. Rubber insulated cable
Rubber insulated cable is flexible, flexible and suitable for disassembly and assembly, but it has poor performance of corona resistance, ozone resistance, heat resistance and oil resistance, so it can only be used as low voltage cable.
Protective layer structure
In order to prevent mechanical damage, electrochemical corrosion and moisture intrusion, the cable core and insulation layer of the power cable have a tight protective layer.