Use

Communication cable refers to the cable used for short-range audio communication and long-range high-frequency carrier and digital communication and signal transmission, and is one of the five major cable products in China. According to the purpose and scope of use of communication cables, they can be divided into six series of products, that is, urban communication cables (including paper-insulated urban telephone cables, polyolefin-insulated polyolefin-sheathed urban telephone cables), long-distance symmetrical cables (including paper-insulated high-and low-frequency long-distance symmetrical cables, copper-core foamed polyethylene high-and low-frequency long-distance symmetrical cables and digital transmission long-distance symmetrical cables), coaxial cables (including small coaxial cables, medium coaxial cables and micro coaxial cables), submarine cables (including symmetrical submarine cables and coaxial cables traditional cable type, ribbon array type and skeleton type), RF cable (including symmetrical RF and coaxial RF).

Model

(1), the city communication cable product model:

CPEV-S

(2), coal mine special communication cable product model:

MHYVR

(3) Shielded communication cable:

HYVP   HYAP   MHYVP   MHYVP   MHYVRP   RVSP(屏蔽双绞线)

(4) Armored communication cable:

HYA53   MHYA32   MHYV22   MHYAV22   MHYAV32   HYAT53   HYV22   HYV32   HYA32

HYV53   HYVP22   HYAP22   HYAP32   MHYVP22   MHYVP32   MHYVRP22   MHYVRP32

(5) Flame-retardant communication cable:

ZR-HYA ZRA-HY-THE ZRC-HY WDZ-HYA ZR-YJYR

Classification

Symmetrical communication cable

The communication loop is composed of two symmetrically arranged wires. High frequency and low frequency. The highest transmission frequency of the former can reach 800 kHz, which corresponds to 180 telephones that can be opened in one loop. The highest transmission frequency of the latter is generally less than 252 kHz, which is equivalent to 60 telephones that can be opened in one loop. The electromagnetic field of the symmetrical communication cable is in an open state (Figure 1). The attenuation and loss of the loop at high frequency are large, and the mutual interference and external interference between the loops are large, so it is difficult to improve the transmission frequency and capacity.

Long-distance symmetrical communication cables are composed of four-wire groups of different numbers and different insulation structures. The common form of the four-wire group is the star winch group, and some use the complex pair winch form (Figure 2). Insulation includes paper tape insulation, paper-rope (paper tape and paper rope) insulation, polyethylene rope-belt insulation, polystyrene rope-belt insulation and foam polyethylene insulation. High-frequency long-distance symmetrical communication cable transmission frequency is high, so the structural performance of the cable is higher. Generally, the rope-insulated star twisted four-wire group structure is adopted. Insulation materials commonly used polystyrene, polyethylene. Paper tape rope insulation is generally used for low-frequency symmetrical communication cables below 252 kHz.

Telephone cable is used in the city, suburbs and industrial and mining enterprises and other smaller areas of the telephone connection of the symmetrical communication cable, often called the city telephone cable. Its main feature is the number of pairs (up to thousands of pairs, usually hundreds or dozens of pairs). Due to the low frequency of use and the short communication distance, the wire diameter is thinner than the long-distance communication cable, generally 0.5mm. There are three types of wire group structures for telephone cables: twisted pair group, star twisted pair group and complex twisted pair group. According to its core insulation and sheath materials, it can be divided into paper insulated lead sheathed cables, polyethylene insulated composite sheath cables, ointment filled waterproof cables, all-plastic cables, etc. Two insulated wire cores in a telephone cable are twisted into pairs at a certain pitch to form an insulated wire pair. The two insulated wires in the wire pair have different colors (usually red and white) to distinguish them when wiring. The core structure of telephone cables is generally divided into two types: concentric type and unit type (Figure 3). Twist pitches of adjacent pairs in the same layer should be different to reduce interaction during calls. A pair of signs (blue and white, respectively) is provided on each floor for easy identification during wiring. In more than 80 pairs of cable often placed in the spare wire pair to replace the defective wire pair. The unit type cable is twisted into a basic unit by 50 pairs or 100 pairs and corresponding preliminary pairs, and then twisted into a cable core by several basic units. After drying, squeeze the upper sheath to make the cable (see figure).

Overhead telephone cables shall be self-supporting, with steel cables bearing the weight of the entire cable. Since the 1960 s, waterproof cables have been developed in which plastic cables are filled with grease to prevent moisture and moisture.

In order to improve the moisture resistance and stability of communication cables, integrated cable sheaths have been widely used in urban telephone cables since the 1970 s. There are three basic types. ① Alpeth: Extrude a layer of polyethylene sheath outside the cable core, and then longitudinally wrap 0.2mm corrugated aluminum tape on the ground. After being filled with polyisobutylene insulation compound, apply a layer of thermoplastic adhesive layer, and extrude a layer of polyethylene sheath on the outermost surface. ② Stalpeth: Wrinkled aluminum strip is longitudinally wrapped with a layer of corrugated steel strip, covered with a layer of thermoplastic material, and the outermost layer is extruded with a layer of polyethylene sheath. ③ Lepeth: The cable core is covered with a layer of polyethylene sheath, which is covered with a layer of viscous thermoplastic material, and the outermost layer of lead pipe is extruded.

coaxial communication cable　　

The communication circuit (coaxial pair) is composed of two inner and outer conductors insulated from each other, and then twisted by one or more coaxial pairs. Coaxial cables are mostly used as long-distance communication trunks, opening multiple carrier communications or transmitting television programs, and are also used for efficient data information transmission.

The two conductors in the coaxial pair are completely concentric, and there is no electromagnetic field outside the outer conductor (Figure 4). Therefore, the attenuation of the transmission signal and the mutual interference between the coaxial pairs are small, and the performance of anti-external interference is also higher than that of the symmetrical cable. Its transmission frequency can reach more than 10~100 MHz. The model of coaxial communication cable is divided according to the size of coaxial pair, there are micro coaxial cable inner conductor diameter n/outer conductor diameter d of 0.6mm/2mm, 0.9mm/3.2mm, etc.), small coaxial cable (n/D = 1.2mm/4.4mm, etc.), medium coaxial cable (n/D = 2.6mm/9.5mm, etc.), large coaxial cable (n/D = 5mm/18mm, 11mm/41mm, etc.).

The inner conductor of the coaxial pair in the coaxial communication cable is copper, and the cross section is cylindrical and solid. In order to improve the mechanical strength (for example, when used as a submarine cable), there are also bimetallic inner conductors with a steel core copper outer layer. The outer conductor is generally made of copper strip, and the common forms are wrinkled edge type, indentation type, tooth locking type, etc. The outer conductor needs good flexibility, high stability and simple processing technology. The insulation of the coaxial to the inner and outer conductor should have a low dielectric coefficient and low dielectric loss, and should also have a certain mechanical strength to support the outer conductor so that it remains concentric with the inner conductor. In order to eliminate the interference between coaxial pairs due to incomplete concentricity, the outer conductor needs to be covered with a shielding layer and then twisted into a cable. The shielding layer is mostly double-layer wrapped steel strip.

Communication Cable Chromatography

core chromatogram

The core chromatogram of the cable can be divided into two categories: ordinary chromatogram and full chromatogram.

Common chromatographic communication cable

Ordinary chromatographic pair concentric communication cable has been rarely used.

Full chromatographic communication cable

The meaning of full color spectrum refers to any pair of core wires in the cable, which can be identified by the tie color of each unit and the color of the wire pair. In other words, the wire pair can be found by giving the wire number, and the wire number can be said by taking out the wire pair.

Full chromatogram twisted pair concentric cable core (rarely used)

Full chromatogram twisted pair unit core

① Full chromatogram twisted pair unit core chromatogram is most used in all plastic local telephone cables. It is composed of white (code W), red (R), black (B), yellow (Y) and purple (V) as the leading color (representing line A), blue (Bl), orange (O), green (G), brown (Br) and gray (S) as the circulating color (representing line B) and ten colors, called 25 pairs of basic U units.