Power cable accessories
The use of power cables has more than 100 years of history. In 1879, American inventor TA Edison wrapped a jute on a copper rod and threaded it into an iron pipe, then filled it with an asphalt mixture to make a cable. He laid the cable in New York and pioneered underground power transmission. The following year, the Englishman Carende invented the asphalt-impregnated paper-insulated power cable. In 1889, the British SZ Ferranti laid a 10 kV oil-impregnated paper insulated cable between London and Dettford. In 1908, a 20 kV cable network was built in the UK. Power cables are becoming more and more widely used. In 1911, 60 kilovolt high-voltage cables were laid in Germany, and the development of high-voltage cables began. In 1913, the German M. Hochstedt developed a component-phase shielded cable, which improved the electric field distribution inside the cable, eliminated the tangential stress on the insulating surface, and became a milestone in the development of power cables. In 1952, Sweden laid a 380-kilovolt ultra-high-voltage cable in a northern power plant, and realized the application of ultra-high-voltage cables. By the 1980s, 1100 kV and 1,200 kV UHV power cables had been made.
Basic structure of power cable:
The basic structure of a power cable consists of a core (conductor), an insulation layer, a shield layer, and a protective layer.
The core is the conductive part of the power cable and is used to transport electrical energy. It is the main part of the power cable.
Insulation layer is to electrically isolate the core from the ground and cores of different phases from each other to ensure the transmission of electrical energy. It is an indispensable part of the power cable structure.
15KV and above power cables generally have conductor shields and insulation shields.
The protective layer
The role of the protective layer is to protect the power cable from the invasion of foreign impurities and moisture, and to prevent external power from directly damaging the power cable.
The main advantage
1 occupies less land. It is usually buried in the soil or laid indoors, in trenches and tunnels, the insulation distance between lines is small, no towers are used, it occupies less land, and basically does not occupy space on the ground.
2High reliability. Affected by climatic conditions and surrounding environment, transmission performance is stable and reliability is high.
3 It has more favorable conditions for the development of ultra-high voltage and large capacity, such as low temperature and super-conductive cables.
4 Large distributed capacitance.
5 Low maintenance workload.
6 The possibility of electric shock is small.
Model of power cable
1. Capitalize the first letter of Chinese Pinyin to indicate the type of insulation, conductor material, inner sheath material, and structural characteristics. For example, Z stands for paper (zhi); L stands for aluminum (lv); Q stands for lead (qian); F stands for phase separation (fen); ZR stands for flame retardance (zuran); NH stands for refractory (naihuo).
2. The outer cover is composed of numbers, and has two digits. No number means no armor layer and no outer layer. The first digit indicates the armor, and the second digit indicates the outer cover. For example, the thick steel wire armor fiber is indicated as 41.
3. The order of the cable model according to the cable structure is generally: insulation material; conductor material; inner sheath; outer sheath.
4. Cable products are indicated by model, rated voltage and specifications. The method is to add the specified voltage, core number and nominal cross-sectional area after the model.
(1) Category: H——City communication cable
(2) Insulation: Y-polyethylene insulation
YF-foam polyolefin insulation
YP-Foam / Solid Skin Polyolefin Insulation
(3) Inner sheath: A——plastic coated aluminum tape bonded shielding polyethylene sheath
S——Aluminum, steel double-layer metal tape shielded polyethylene sheath
V——Polyvinyl chloride sheath
(4) Features: T-filling with petroleum paste
G-high frequency isolation
(5) Outer sheath: 23——Double-layer anticorrosive steel tape wrapped with polyethylene outer covering
33——Single layer of fine steel wire armored polyethylene quilt
43——Single-layer thick steel wire armored polyethylene quilt
53——Single-layer steel strip wrinkled longitudinally sheathed polyethylene outer covering
553——Double-layer steel strip wrinkled longitudinally sheathed polyethylene outer covering
2) BV copper core PVC insulated wire;
BLV aluminum core PVC insulated wire;
BVV copper core PVC insulated PVC sheathed wire;
BLVV aluminum core PVC insulated PVC sheathed wire;
BVR copper core PVC insulated flexible wire;
RV copper core PVC insulated installation cord;
RVB copper core PVC insulated flat cable
BVS copper core PVC insulated twisted flexible cord;
RVV copper core PVC insulated PVC sheathed flexible wire;
BYR polyethylene insulated flexible wire;
BYVR polyethylene insulated PVC sheathed flexible cord;
RY polyethylene insulated flexible wire;
RYV polyethylene insulated PVC sheathed flexible cord
3) WD: halogen-free low-smoke type
ZR: flame retardant