Low voltage power cable structure and advantages

A cable is a conductor covered with an insulating layer, a protective layer, a shielding layer, etc. for transmitting power, signal current, and signal voltage. According to the voltage, it can be divided into high-voltage cables and low-voltage cables. Compared with low-voltage overhead lines and low-voltage overhead insulated lines, low-voltage cable lines have higher costs and are more difficult to lay and maintain. However, due to their reliable operation, no poles, no ground occupation, no unsightly appearance, and less external influence, etc. It is widely used in low-voltage power distribution systems.

Low voltage wire insulation structure

It consists of three parts: the core, the insulating layer and the protective layer. The wire core is used to conduct current and is generally formed by twisting multiple copper wires or multiple aluminum wires. Low-voltage cables are available in single-core, double-core, three-core, and four-core types. Two-core cables are used for single-phase lines, three-core and four-core cables are respectively used for three-phase three-wire lines and three-phase four-wire lines, and single-core cables can be applied to single-phase lines or three-phase lines as required. Commonly used low-voltage cable core cross-sectional areas are 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240 mm, etc.

1. Insulation layer

An insulating material with a specific function of withstand voltage in cables. The insulation layer is divided into two types: core insulation and tape insulation: the insulation covering the core is called core insulation; the insulation of the multi-core cable's insulated cores combined and then covered is called tape insulation. The tape insulation is separated from the protective layer to form reliable ground insulation. The insulating layer is usually made of oil-impregnated paper, plastic, rubber, etc.

(1) Paper-insulated cables are cables with impregnated cable paper as insulation, which are collectively referred to as paper-insulated cables. According to the situation of paper impregnation, it can be divided into: ① oil-impregnated paper insulated cable; ② dry insulated cable; ③ non-drip cable.

(2) Cables whose insulating layers are extruded and cross-linked by thermoplastic plastics, collectively referred to as plastic cables, are widely used. Plastic cables can be divided into three types: PVC cables, polyethylene cables and XLPE cables. Cables with natural styrene-butadiene rubber, butyl rubber and ethylene-propylene rubber as insulating layers are called rubber cables. Low-voltage cables with a voltage level of 1kV can use paper-insulated cables and plastic cables, and plastic cables are often used; low-voltage cables with a voltage level of 0.5 kV mostly use rubber cables.

2. Protective layer

One or more layers of metallic or non-metallic material covering the outside of the cable. The protective layer is used to protect the insulating layer from damage by external force and intrusion of moisture during transportation, laying and use.

(1) Paper insulated cable protective layer. The protective layer of the paper insulated cable is divided into two parts: the inner sheath and the outer sheath. The inner sheath is directly extruded on the insulating layer, which not only protects the insulation from moisture, but also prevents the outflow of insulating oil, and has a certain mechanical strength. There are three types of inner sheaths: lead, aluminum and polyvinyl chloride. The outer sheath protects the inner sheath to increase the cable's ability to withstand mechanical external forces and anti-corrosion. The outer sheath includes an inner liner layer, a metal armor layer and an outer quilt layer. The inner liner layer protects the metal sheath from being damaged by the metal armor layer, and anti-corrosion measures can be added; the metal armor layer can withstand mechanical external forces; the outer quilt layer can protect the armored metal from external corrosion.

(2) Plastic cable protective layer. Usually a PVC sheath is used over the plastic insulation.

(3) The protective layer of the rubber cable. The protective layer of the rubber cable is divided into an inner sheath and an outer sheath. There are three types of inner sheath: PVC sheath, neoprene sheath (non-flammable rubber) and lead sheath; the outer sheath is divided into three types: steel tape armor, rubber sheath and plastic sheath.

Advantages of electrical wire low voltage

1. Small footprint, all kinds of wires rotating in mid-air are messy, occupying a lot of space in visual effects, however, power cable manufacturers say that power cables can be laid in soil, tunnels and indoors without erecting Electric poles, because of their small insulation distances, save a lot of space and don't spoil the look of the place you're going.

2. The reliability of power cables is high. The protective layer of power cables is not only waterproof, but also prevents the erosion of cables by other impurities, reducing the impact of climate and surrounding environment. The cable manufacturer tells you that the insulation layer ensures the independence of power transmission between cables. stability and stability.

3. There is a lot of room for improvement. With the continuous improvement of power capacity and voltage of power cables, the use value is also increasing, and the demand for this has also increased to a certain extent.

4. Once laid, the maintenance workload is relatively small. The power cable manufacturer tells you that the installation channel of the power cable does not need to be exposed, so the corresponding damage is also reduced, and the maintenance of it is also less than that of ordinary wires.

5. For large distributed capacitance, the conductive core materials used in the power cord are all highly conductive. There are usually multiple conductive cores inside the cable. Compared with the overhead line of the same cross-section, the power cord per unit length has a larger capacity.

6. The possibility of electric shock is small. The conductive core of the power cable is wrapped by an insulating layer, a shielding layer and a protective layer. With layer-by-layer protection and its installation method, the aging speed of the line will be slowed down, and the possibility of damage will also be reduced. Reduce the possibility of electric shock.