There are many ways to classify power cables, such as by voltage, cross-sectional area, conductor core size, and insulation material.
Power Cable Types
1. Classification by Voltage
Cables are manufactured according to specific voltage levels, in the following order: 0.5, 1, 3, 6, 10, 20, 35, 0.60, 110, 220, and 330 kV.
Based on construction requirements, the structural characteristics of cable joints and terminals, and operation and maintenance procedures, power cables can be categorized as low-voltage power cables (1 kV), medium-voltage power cables (3-35 kV), and high-voltage power cables (60-330 kV).
Power Cable Types and Applications
II. Classification by Conductive Core Cross-sectional Area
my country's power cable conductor cores have 19 nominal cross-sectional areas: 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400, 500, 625, and 800 mm.
High-voltage oil-filled cables have six nominal cross-sectional areas: 100, 240, 400, 600, 700, and 845 mm.
III. Classification by Conductive Core
Single-core, three-core, four-core, five-core, and single-core cables are typically used to transmit single-phase AC and DC power, and can also be used in special applications (such as high-voltage motor lead-out cables). Oil-filled and gas-filled high-voltage cables of 60 kV and above are mostly single-core, while two-core cables are mostly used to transmit single-phase AC or DC power. Three-core cables are mainly used for three-phase AC power grids and are widely used in various cable lines below 35kV. Four-core cables are mainly used for low-voltage distribution lines and three-phase four-wire systems with neutral grounding (the cross-sectional area of the fourth core of a four-core cable is usually 40% of the cross-sectional area of the main core). Only cables with a voltage level of 1kV have two cores and four cores. The number of control cable cores ranges from one to dozens. 4. Classification by structural characteristics (1) Turnkey type. All cores are covered with full insulation material and placed in the same sheath. (2) Phase-split screen type, mainly phase-split screen type, generally used for 10-35kV voltage level, divided into oil-paper insulation type and plastic insulation type. (3) Steel pipe type The outer layer of the cable insulation layer adopts a steel pipe sheath, which is divided into steel pipe oil-filled and air-filled cable and steel pipe hydraulic and pneumatic cable. (4) Flat type. The cross section of the three-core cable is flat and is usually used for long submarine cables. (5) Independent type, the cable sheath has pressure, divided into user oil-filled cable and gas-filled cable.
IV. Classification and laying according to environmental conditions
According to the environmental conditions of cable laying, it can be divided into underground direct burial, underground pipeline, air, underwater river crossing, underwater ocean crossing, mine, high altitude, salt spray, large height difference, multiple movements, hot and humid, etc.
Environmental factors usually have certain special requirements for the protective layer, such as mechanical strength, corrosion resistance or increased softness.
VI. Classification by electrical properties
According to the nature of power transmission, it is divided into AC power cable and DC power cable. At present, the insulation of power cable is designed according to AC. The electric field distribution of DC power cable is different from that of AC power cable and requires special design.
VII. Classification by insulation material
1. Plastic insulated cable
Plastic insulated cable is simple to manufacture, light in weight, easy to make end and intermediate joints, small bending radius, and simple to lay. It is easy to maintain, resistant to chemical corrosion, and has certain water resistance. It is suitable for high profile and vertical laying. Plastic insulated cables include polyvinyl chloride insulated cables, polyethylene insulated cables and cross-linked polyethylene insulated cables. Polyethylene insulated cables are generally used for cable lines below 10kV, while cross-linked polyethylene insulated cables are mainly used for cable lines above 6kV and even 110-220kV. 2. Rubber cables Rubber has elasticity, stable performance, good electrical, mechanical and chemical properties, so it is mainly used for cable lines below 6kV. 3. Flame-retardant polyoxyethylene insulated cables 4. Oil and paper insulated power cables Oil-paper insulated power cables are widely used. They are widely used in 330 kV cables of various voltage levels. Oil-free paper insulated power cables use paper as the main insulating material and are fully impregnated with insulating oil-discharging agents. According to the different insulation structures and concentrations, oil-impregnated paper insulated power cables can be divided into the following categories: (1) Ordinary adhesive impregnated insulated cables. It is a commonly used oil-coated paper insulated cable. The free agent of this cable is a cat leaching agent mixed with low-voltage cable oil and rosin. According to the different structures, this type of cable can be divided into full-inclusion type, phase-separated lead (aluminum) clad type and phase-separated shielded full-inclusion type. The multiple cores of the cable share a metal sheath. This type of electrical coupling is mainly used for voltage levels of 10KV and below. Each insulating core of the phase-separated lead (aluminum clad cable) has a metal sheath. The insulating cores of the phase-separated shielded sensitive cable are each provided with a shielding layer and share a metal sheath. The latter two cables are mainly used for voltage levels of 20-35kV. (2) Drip insulation cable. This is a sticky waste paper insulated cable with higher insulation sensitivity. It is made by dripping and impregnation after impregnation. The drip insulation is suitable for voltage levels below 10kV and occasions with large current drops.
(3) Do not drip and soak cable. Its structure and size are the same as those of the drip-dry insulation cable, but it is made by leaching with a submerged leaching agent. The unsaturated solvent is a mixture of low-bed cable oil, some plastics and synthetic wax. Unsaturated impregnated cable is suitable for high-loss cable lines and tropical areas with voltage levels not exceeding 10kV.
(4) Hydraulic oil-impregnated paper insulated cables, including self-contained inflatable cables and steel tube inflatable cables. The cable impregnant is generally low-viscosity cable oil. Oil-filled cables are used for lines of 35kV and above.
(5) Pneumatic oil-transported paper insulated cables, including self-contained inflatable cables and steel tube inflatable cables. They are mainly used for cable lines of 35kV and above.
Power cables contain a lot of content and are a huge subject. If you want to understand them in depth, you can only explore and learn slowly by yourself. I hope this article can give you a more comprehensive understanding of wires and cables. Similarly, it is best if they can be used reasonably in your daily life.
