Basic Structure and Main Classification of Power Cables

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Power cables are a vital component of modern electrical systems, enabling safe and reliable transmission of electrical energy from power sources to loads. From residential buildings and industrial plants to renewable energy facilities and high‑voltage transmission networks, power cables form the backbone of electricity distribution. A power cable is specifically designed for power transmission and typically consists of a conductor, insulation, shielding, and protective covering. Unlike signal or communication cables, power cables are engineered to carry high currents while maintaining insulation integrity, mechanical strength, and thermal stability. They are primarily installed in urban underground power grids, power station outgoing lines, and similar applications. According to voltage level, power cables can be classified into low voltage, medium voltage, high voltage, and extra‑high voltage categories, with insulation materials including polypropylene, cross‑linked polyethylene (XLPE), and others.

Basic Structure

The basic structure of a power cable generally comprises four essential components: conductor, insulation, shielding, and protective sheath.

Conductor (Core)

The conductor is usually made of copper or aluminum to ensure excellent electrical conductivity. It is the conductive part of the power cable, responsible for transmitting electrical energy and serving as the main component of the cable.

Insulation Layer

The insulation layer electrically isolates the conductor from the earth and between conductors of different phases, ensuring safe power transmission. It is an indispensable part of the power cable structure. Insulation materials include oil‑impregnated paper, plastics (PVC, polyethylene, XLPE), and rubber. The insulation prevents current leakage and withstands high voltages.

Shielding Layer

Power cables rated at 15 kV and above generally include a conductor shield and an insulation shield. These shielding layers help distribute the electric field uniformly, reduce partial discharge, and protect the insulation from stress.

Protective Sheath
The protective sheath safeguards the power cable against ingress of external impurities and moisture, as well as direct mechanical damage. It provides mechanical protection and environmental resistance.

Main Classification

By Voltage Level

Low Voltage Power Cable – Suitable for fixed installation in AC 50 Hz transmission and distribution lines with rated voltages up to 3 kV. Commonly used for internal power distribution in buildings. Yongshang’s Low Voltage Power Cable series offers excellent conductivity and reliable insulation for residential and commercial applications.

Medium Voltage Power Cables – Generally refer to cables rated at 35 kV and below. This category includes PVC, polyethylene, and XLPE insulated cables. Yongshang’s Medium Voltage Power Cables are designed for stable operation in urban distribution networks and industrial facilities.

High Voltage Power Cables – Rated at 110 kV and above. These include polyethylene and XLPE insulated cables. Yongshang’s High Voltage Power Cables are engineered with advanced materials to ensure long‑term reliability in critical transmission lines.

Extra‑High Voltage Cables – Rated from 275 kV up to 800 kV.

Ultra‑High Voltage Cables – Rated at 1000 kV and above, mainly used for backbone grid transmission.

By Insulation Material

Oil‑impregnated Paper Insulated Power Cables – These use oil‑impregnated paper as the insulation. They have the longest service history, offering safety, reliability, long service life, and low cost. The main drawback is the limitation in laying height difference. Since the development of non‑draining paper insulation, this limitation has been overcome, allowing continued widespread use.

Plastic Insulated Power Cables – The insulation layer is extruded plastic. Common plastics include PVC, polyethylene, and XLPE. Plastic cables have a simple structure, convenient manufacturing, light weight, and easy installation without height difference restrictions. They are widely used as medium and low voltage cables and are increasingly replacing viscous oil‑impregnated paper cables. The main disadvantage is the phenomenon of treeing breakdown, which limits their use at higher voltages.

Rubber Insulated Power Cables – The insulation layer is made of rubber compounded with various additives, fully mixed, extruded over the conductor, and then vulcanized by heating. These cables are flexible and elastic, suitable for frequent movement and applications requiring small bending radii. Common rubber compounds include natural rubber‑SBR blends, EPDM, and butyl rubber.

Other Important Types

Aluminum Alloy Cable – With improved bending performance, creep resistance, and corrosion resistance, Aluminum Alloy Cable ensures stable continuous performance during prolonged overloading and overheating. It is lighter in weight and has lower material costs. It is an excellent lightweight alternative to copper cables in many applications.

Aerial Insulated Cable – Designed for overhead power distribution, Aerial Insulated Cable provides enhanced safety against short circuits and reduces power outages caused by tree branches or wildlife contact. It is widely used in rural electrification and urban overhead line conversions.

Hebei Yongshang Cable Group’s Power Cable Portfolio

Hebei Yongshang Cable Group offers a full range of power cables, covering Low Voltage Power Cables, Medium Voltage Power Cables, High Voltage Power Cables, Aluminum Alloy Cables, and Aerial Insulated Cables. Our products are built with advanced materials and precision engineering, ensuring stable performance and reliable quality. Featuring excellent conductivity, robust insulation layers, and outstanding heat and weather resistance, Yongshang’s power cables are ideal for industrial, commercial, and infrastructure applications, serving power transmission and distribution in diverse scenarios. Our cables have been successfully applied in numerous large‑scale projects, including the Beijing 2022 Winter Olympics, the Beijing National Library Phase II renovation, the Qingdao Metro, and the Beijing Metro, achieving excellent results. With a commitment to quality and innovation, Hebei Yongshang Cable Group continues to empower the world’s power infrastructure.