There are a wide variety of cables with diverse classification methods. From the most commonly used dimensions, cables can be classified by voltage level, insulating material, conductor material and application purpose, which are introduced one by one below.

I. Classification by Voltage Level

This is the most basic classification method. Low-voltage cables are used in power distribution systems of 1kV and below, commonly found in homes, shops and ordinary factories, and are the most frequently encountered type in daily life. Medium-voltage cables are used in 6kV to 35kV power distribution networks, connecting substations and regional distribution rooms. High-voltage cables are used in 66kV to 220kV transmission lines, undertaking power transmission between cities or regions. Extra-high-voltage cables are used for 330kV to 750kV, and ultra-high-voltage cables are used for 1000kV and above, mainly for long-distance, large-capacity backbone power grid transmission.

II. Classification by Insulating Material

The insulating material determines the performance and application scenarios of the cable. PVC insulated cables are the most common type, with low price and good flame retardancy, but the maximum operating temperature is relatively low, only 70°C to 90°C, suitable for general indoor environments. XLPE insulated cables are the main products in current engineering, with high temperature resistance grade up to 90°C, large current-carrying capacity and good mechanical properties, widely used in various power projects. Rubber insulated cables are soft and elastic, suitable for occasions with frequent movement and frequent bending, such as welding machine cables and crane cables. Mineral insulated cables are entirely made of inorganic materials, with extremely strong fire resistance, which can continuously supply power for more than 3 hours in a 950°C flame, and are used in places with extremely high fire protection requirements such as fire protection systems and high-rise buildings.

III. Classification by Conductor Material

Copper core cables have good electrical conductivity, low resistivity, less heat generation and high mechanical strength, and are the most widely used type. Aluminum core cables are light in weight and low in price, but have smaller current-carrying capacity under the same cross-sectional area, and are mostly used for large-cross-section overhead lines with cost sensitivity. Aluminum alloy cables are alternative products developed in recent years. By adding alloy elements to the aluminum matrix and undergoing special treatment, their mechanical properties and creep resistance are greatly improved, and the comprehensive cost performance is better than pure aluminum cables.

IV. Classification by Application Purpose

Power cables are used for power transmission and are the main force in the cable family. Control cables are used in the control loops of electrical equipment, with a large number of cores, small cross-section, and often with a shielding layer. Communication cables are used to transmit voice and data signals, including telephone lines, network cables, coaxial cables and optical fiber cables. Fire-resistant cables can maintain power supply for a certain period of time in flames, and are used in fire protection systems. Flame retardant cables can prevent the spread of flame when encountering fire, and are used in crowded places. Special cables are designed for special environments, such as high-temperature resistant cables for the metallurgical industry, cold-resistant cables for alpine regions, waterproof cables for underwater engineering, and rodent and termite resistant cables for field or underground environments.

V. Classification by Structural Features

Armored cables add a steel tape or steel wire armor layer outside the insulation layer to enhance the mechanical damage resistance, suitable for direct burial or occasions subject to external forces. Non-armored cables have no metal protective layer, are light in weight and low in price, suitable for indoor cable tray or conduit laying. Single-core cables are used for single-phase AC or DC power transmission, three-core cables are used for three-phase AC power grids, and 4-core and 5-core cables are mostly used in low-voltage power distribution systems.

Summary: Cables have multiple classification dimensions. In actual type selection, factors such as voltage level, usage environment, laying method, current-carrying capacity requirement and economic cost should be comprehensively considered to select the most suitable cable type.