Basic knowledge of the hottest cable

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Basic knowledge of cables

wire and cable: it is usually twisted by several wires or groups of wires [at least two wires in each group], similar to rope. Each group of wires is insulated from each other and often twisted around a center, and the entire outer surface is covered with a highly insulated covering layer. It is mainly used for transmitting, distributing electric energy or transmitting electric signals

wires and cables are mainly composed of the following four parts

1. Conductive core: made of high conductivity materials (copper or aluminum). According to the requirements of laying conditions on the flexibility of the cable, each wire core may be twisted by a single wire or multiple wires

2. Insulating layer: the insulating material used as cable should have high insulation resistance. The commonly used insulating materials in cables can judge whether a material is transparent, including oil impregnated paper, PVC, polyethylene, cross-linked polyethylene, rubber, etc

3. Sealing sheath: protect the insulated wire core from damage by machinery, moisture, moisture, chemicals, light, etc. For insulation susceptible to moisture, lead or aluminum extruded sealing sheath is generally used

4. Protective covering layer: used to protect the sealing sheath from mechanical damage. Generally, galvanized steel strip, steel wire or copper strip, copper wire, etc. are used as armor to wrap outside the sheath (called armored cable), and the armor layer plays the role of shielding electric field and preventing external electromagnetic wave interference at the same time. In order to avoid the corrosion of steel belt and steel wire by the surrounding medium, they are generally coated with asphalt or wrapped with jute layer or extruded polyethylene and PVC sheath

II. Wire and cable specification

wire and cable specification is the meaning of the representation of the number of cores and cross-sectional dimensions of wires and cables. The complete naming of wires and cables is usually complex, so people sometimes use a simple name (usually the name of a category) combined with the model and specification to replace the complete name. For example, "low voltage cable" represents all plastic insulated power cables of 0.6/1kv grade. The type spectrum of cables is relatively perfect. It can be said that as long as the standard model and specification of wires and cables are written, the specific products can be defined

III. application classification of wires and cables

(I) classification by insulating materials, such as oil impregnated paper insulated cables, PVC cables, XLPE cables, etc

(II) according to the purpose, it is divided into power cable, communication cable and control cable. It is applied to power system, information transmission system, mechanical equipment and instrument system respectively

1. Power system

the power system reserves a distance of 20mm. The wire and cable products used in the system mainly include overhead bare wires, bus bars (buses), power cables (plastic cables, oil paper power cables (basically replaced by plastic power cables), rubber sheathed cables, overhead insulated cables), branch cables (replacing some buses), electromagnetic wires, and electrical equipment wires and cables for power equipment

2. Information transmission system

the wires and cables used in the information transmission system mainly include local telephone cables, television cables, electronic cables, radio frequency cables, optical fiber cables, data cables, electromagnetic cables, power communication or other composite cables

3. Mechanical equipment, instrument and meter system

this part is applied to almost all products except overhead bare wires, but mainly power cables, electromagnetic wires, data cables, instrument and meter cables, etc

(III) according to product classification, it is divided into five categories

1. Bare wires and bare conductor products

the main features of this category of products are: pure conductor membrane materials: bipolar membrane electrodialysis membrane, high-performance lithium battery membrane, high-voltage reverse osmosis composite membrane materials, high-selectivity nanofiltration membrane materials metal, no insulation and sheath layer, such as steel cored aluminum stranded wire, copper aluminum busbar, electric locomotive line, etc; The processing technology is mainly pressure processing, such as smelting, calendering, drawing, stranding/tight pressing stranding, etc; The products are mainly used in suburbs, rural areas, user mainlines, switchgear, etc

2. Power cable

the main features of this kind of products are: extruding (winding) the insulation layer outside the conductor, such as overhead insulated cable, or several cores stranded (corresponding to the phase line, zero line and ground wire of the power system), such as overhead insulated cable with more than two cores, or adding a sheath layer, such as plastic/rubber sheathed wire and cable. The main process technologies include drawing, stranding, insulation extrusion (wrapping), cabling, armor, sheath extrusion, etc. different process combinations of various products are different

22. Pressure plate [compression plate]

products are mainly used for the transmission of strong electric energy in power generation, distribution, transmission, transformation and power supply lines, with large current (tens of amps to thousands of AMPS) and high voltage (220V to 500kV and above)

3. Wires and cables for electrical equipment

the main characteristics of this kind of products are: a wide range of varieties and specifications, a wide range of applications, and the use voltage is more than 1KV. In the face of special occasions, new products are constantly derived, such as fire-resistant cables, flame-retardant cables, low smoke halogen-free/low smoke low halogen cables, anti termite, anti mouse cables, oil/cold/temperature/wear-resistant cables, medical/agricultural/mining cables, thin-walled wires, etc

4. Communication cables and optical fibers

from simple telegraph cables in the past to thousands of pairs of voice cables, coaxial cables, optical cables, data cables, and even combined communication cables. The structure size of this kind of products is usually small and uniform, and the manufacturing accuracy is high

5. Electromagnetic wire (winding wire)

is mainly used for various motors, instruments and meters

IV. what is the difference between wires and cables

in fact, there is no strict boundary between "wire" and "cable". Generally, products with few cores, small diameter and simple structure are called wires, those without insulation are called bare wires, and others are called cables; The larger conductor cross-sectional area (more than 6 mm2) is called large wire, the smaller one (less than or equal to 6 mm2) is called small wire, and the insulated wire is also called cloth wire. However, with the expansion of the scope of use, many varieties of "cable in cable" and "cable in cable". Therefore, there is no need to strictly distinguish. In daily habits, people call household cloth wires wires wires and power cables for short cables

the wire is composed of one or several soft wires, covered with a light and soft protective layer; The cable is composed of one or several insulated conductors, which are covered with a tough outer layer made of metal or rubber. Cables and wires are generally composed of three parts: core wire, insulating sheath and protective sheath

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