2025-11-13
Classified by voltage level:
The function of power cables is to transmit and distribute electrical energy. The two most important technical parameters of electrical energy are capacitance and voltage, especially voltage, i.e., voltage rating. The rated voltage of a cable is usually expressed as u₀/u, where u₀ is the design voltage between the cable core conductor and the metal outer sheath or metal shield, also called phase voltage, and u is the design voltage between the core conductors, also called line voltage.
In my country, there are 19 types of cables classified according to their rated voltage level. Power cables are generally divided into the following four categories based on voltage level:
(1) Low-voltage power cables, U≤1kV, 0.6/1, 1/1kV;
(2) Medium-voltage/medium-high-voltage power cables, 6kV≤u≤35kV, 3.5/6, 6/6, 6/10, 8.7/10, 8.7/15, 12/15, 12/20, 18/20, 18/30, 21/35, 26/25kV;
(3) High-voltage power cables, 63kV≤U≤220kV, 36/63, 48/83, 64/110, 127/220kV;
(4) Ultra-high-voltage power cables, U≥330kV.
For on-site withstand voltage tests of 190/330kV and 290/500kV power cables, whether DC or AC, the reading voltage Uₛ is determined primarily by the cable parameter u₀/u, in addition to considering the cable's structural type and insulation material. Locating faults in the main insulation and sheath insulation of power cables generally involves applying different voltage levels to the faulty cable; the maximum test voltage is also determined based on the cable parameter u₀/u.
Classification by Insulation Material:
Power cables are mainly composed of two parts: conductors and insulators. Currently, the conductor material is mainly aluminum and copper, while the insulation material is more varied, determining the structural type and main performance of the power cable. They are generally classified into two main categories: oil-impregnated paper-insulated power cables and plastic-insulated power cables, which are described below:
Oil-impregnated Paper-insulated Power Cables:
Oil-impregnated paper-insulated power cables are a type of cable with a long history of application and wide distribution. Their insulation material is a composite of insulating paper and an insulating impregnating agent. Depending on the impregnating agent and structure, there are several types.
Ordinary Adhesive Oil-impregnated Paper Cables: Their insulating impregnating agent is a mixture of low-voltage cable filament and rosin. They are widely used in voltage levels of 35kV and below. Structurally, they are usually divided into two types: uniform sheathed and phase-separated lead (aluminum) sheathed. For 10kV and below, the insulated cores all have a metal (lead or aluminum) sheath, which is the phase-separated lead (aluminum) sheathed type. Each insulated core of a 20-35KV cable has a metal (lead or aluminum) sheath, i.e., it is divided into lead (aluminum) sheathed type. The cable structure is shown in the figure.
