Classification by Voltage Level
Based on voltage levels, power cables can be categorized into medium-to-low voltage cables (35 kV and below), high-voltage cables (above 110 kV), extra-high voltage cables (275–800 kV), and ultra-high voltage cables (1000 kV and above). Additionally, they can be classified by current type into AC cables and DC cables.
Classification by Insulation Material
1. Oil-Impregnated Paper Insulated Power Cables: These cables utilize oil-impregnated paper as their insulating medium. They boast the longest history of application among cable types. They are safe, reliable, offer a long service life, and are cost-effective. Their primary drawback is that their installation is restricted by elevation differences (head). However, with the development of non-draining (non-dripping) impregnated paper insulation, this limitation regarding elevation differences was resolved, allowing oil-impregnated paper insulated cables to continue enjoying widespread application.
2. Plastic Insulated Power Cables: These cables feature an insulating layer composed of extruded plastic. Commonly used plastics include polyvinyl chloride (PVC), polyethylene (PE), and cross-linked polyethylene (XLPE). Plastic cables possess a simple structure, are easy to manufacture and process, are lightweight, facilitate convenient installation, and are not subject to limitations regarding installation elevation differences. Consequently, they are widely used as medium-to-low voltage cables and show a trend toward replacing viscous oil-impregnated paper cables. Their most significant drawback is the susceptibility to "treeing breakdown" phenomena, which limits their application at higher voltage levels.
3. Rubber Insulated Power Cables: The insulating layer of these cables consists of rubber blended with various compounding agents; this mixture is thoroughly compounded, extruded over the conductive core, and then cured through heating (vulcanization). These cables are soft and highly elastic, making them suitable for applications involving frequent movement or requiring small bending radii during installation.
Commonly used rubber compounds for insulation include natural rubber-styrene-butadiene rubber (SBR) blends, ethylene-propylene rubber (EPR), butyl rubber, and others.
Classification by Voltage Level (Detailed)
1. Low-Voltage Cables: Suitable for fixed installation in power transmission and distribution lines operating at an AC frequency of 50 Hz and a rated voltage of 3 kV or below, used for the conveyance of electrical energy.
2. Medium-to-Low Voltage Cables (Generally referring to 35 kV and below): Includes polyvinyl chloride (PVC) insulated cables, polyethylene (PE) insulated cables, cross-linked polyethylene (XLPE) insulated cables, and similar types. 3. High-voltage cables (typically 110 kV and above): Polyethylene cables, cross-linked polyethylene (XLPE) insulated cables, etc.
4. Ultra-high-voltage cables (275–800 kV).
5. Extra-high-voltage cables (1000 kV and above).
