Features and Advantages of Aluminum Alloy Cable
May 10,2022
Power cables are used for the transmission and distribution of electrical energy. They are commonly utilized in urban underground power grids, generating station lead lines, internal power supply for industrial and mining enterprises, and underwater power transmission lines across rivers and seas.
By Voltage Level:
Low and Medium Voltage Cables: These include cables rated up to 35 kV.
High Voltage Cable Types: These are cables rated above 110 kV.
Extra High Voltage Cables: These range from 275 kV to 800 kV.
Ultra High Voltage Cables: These are rated at 1000 kV and above.
Additionally, cables can be categorized into AC cables and DC cables based on the type of current.
By Insulation Material:
Oil-Impregnated Paper Insulated Power Cables: These cables use oil-impregnated paper as insulation and have the longest history of use. They are safe, reliable, durable, and cost-effective. The main drawback is that their installation is restricted by drop height. However, the development of non-dripping impregnated paper insulation has resolved the drop height limitation issue, allowing these cables to continue being widely used.
Plastic Insulated Power Cables: These cables have insulation layers made from extruded plastics, such as PVC, polyethylene, and cross-linked polyethylene. Plastic cables are simple in structure, easy to manufacture, lightweight, and convenient to install without restrictions on drop height. They are widely used for medium and low voltage applications and are increasingly replacing impregnated paper cables. The major limitation is the occurrence of treeing breakdown, which restricts their use at higher voltages.
Rubber Insulated Power Cables: These cables have an insulating layer made of rubber combined with various additives, which is then extruded onto the conductive core and vulcanized. They are flexible, elastic, and suitable for frequently moved installations with small bending radii. Common rubber materials used for insulation include natural rubber-styrene-butadiene rubber blends, ethylene-propylene rubber, and butyl rubber.
By Voltage Level:
Low Voltage Cables: Suitable for fixed installation in AC 50Hz distribution lines with a rated voltage of up to 3 kV.
Medium and Low Voltage Cables: Generally refer to cables rated up to 35 kV, including PVC insulated cables, polyethylene insulated cables, and cross-linked polyethylene insulated cables.
High Voltage Cables: Generally refer to cables rated 110 kV and above, such as polyethylene cables and cross-linked polyethylene insulated cables.
Extra High Voltage Cables: Rated from 275 kV to 800 kV.
Ultra High Voltage Cables: Rated at 1000 kV and above.
Any power cable consists of three basic components: the conductive core, insulation layer, and protective layer.
Conductive Core:
The core is the conductive part of the power cable, used to transport electrical energy and is the main component of the cable. The loss in the core is determined by the cross-sectional area and conductivity of the material. To reduce losses, the core is generally made of copper or aluminum, which have high conductivity.
Insulation Layer:
The insulation layer electrically separates the core from the ground and between different phases, ensuring safe energy transmission. It isolates the core conductor from the protective layer to prevent leakage. The insulation layer must withstand high electrical stress and is susceptible to partial discharge due to unavoidable air bubbles. These discharges can cause ozone corrosion, so the insulation must have good corona resistance. Currently, cross-linked polyethylene dominates as insulation material for cables rated up to 110 kV.
Shielding Layer:
Power cables rated 15 kV and above generally include conductor shielding and insulation shielding layers. For cables rated 6 kV and above, shielding layers help contain the electromagnetic fields generated by the current within the cable, protecting surrounding components. In the event of cable damage, leakage current will flow along the shielding layer to the grounding network, providing protective functionality.
Protective Layer:
The protective layer safeguards the power cable from external impurities, moisture, and mechanical damage. It includes inner and outer protective layers that shield the insulation layer. The quality of the protective layer directly affects the cable's lifespan. The concentric layer located between the armor layer and metal sheath, as well as the filling material in high voltage cables, also serves as part of the protective layer.
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