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What is cable, cable knowledge introduction


First, the definition of cable

Cable is a kind of wire products used to transmit electric energy information and realize electromagnetic energy conversion. Both conductor and insulation layer, sometimes also added to prevent moisture invasion of the tight inner protective layer, or also add mechanical strength of the outer protective layer, the structure is more complex, the product with larger cross-sectional area is called cable.

Two, cable classification

Cables include power CABLE, CONTROL cable, compensation cable, shielded cable, high temperature cable, computer cable, signal cable, coaxial cable, refractory cable, Marine cable, mining cable, aluminum alloy cable and so on. They are composed of single or multiple strands of wire and insulation layer, used to connect circuits, electrical appliances, etc.

Cables can be divided into DC cables and AC cables according to the system of photovoltaic power station. According to different uses and operating environment, the cables are classified as follows:

1. Dc cable

(1) Series cables between components.
(2) Parallel cables between clusters and between clusters to DC distribution box (bus box).
(3) Cables between DC distribution box and inverter.

The above cables are DC cables, which are laid outdoors more often, and need to be moisture-proof, sun-proof, cold-resistant, heat-resistant and UV resistant. In some special environments, acid and alkali and other chemical substances are also needed.

2. Ac cables

(1) Connecting cable between inverter and boost transformer.
(2) The connection cable between the boost transformer and the distribution device.
(3) Connecting cables between the distribution device and the power grid or users.

This part of the cable is AC load cable, indoor environment laying more, can be selected according to the general requirements of power cable selection.

Three, the cable model

1. Composition and sequence
The model composition and sequence of electric wires and cables are as follows: [1: type, use], [2: conductor], [3: insulation], [4: inner sheath], [5: structural features], [6: outer sheath or derivations], [7: Usage characteristics]
Items 1-5 and 7 are represented by pinyin letters, polymer materials are represented by the first letter of the English name, each item can be 1-2 letters; The sixth term is 1-3 numbers.

2. Common code
Purpose Code - not marked as power cable, K- (control cable), P- (signal cable);
Conductor material code - not labeled copper (may also be labeled CU), L- (Aluminum);
The inner sheath code -Q- (lead bag), L- (aluminum bag), H- (rubber sleeve), V- (PVC sheath), the inner sheath is generally not marked;
Outer envelope code -V- (polyvinyl chloride), Y- (polyethylene power cable);
Derived code -D- (no trickle), P- (dry insulation);
Special product code -TH- (humid hot zone), TA- (dry tropical zone), ZR- (Flame retardant), NH- (fire resistant), WDZ- (low smoke halogen free, enterprise standard).

3. The principle of omission

Omitted principle in the model: Copper is the main conductor material used in wire and cable products, so the copper core code T is omitted, except bare wire and bare conductor products. Bare wire and bare conductor products, power cable, electromagnetic wire products do not indicate the category of code, electrical equipment wire and cable and communication cable class is not listed, but listed small class or series code, etc.
The seventh item is a variety of special occasions or additional special use requirements of the mark, after the "-" with pinyin alphabet mark. Sometimes this item is put first to highlight it. Such as ZR- (flame retardant), NH- (fire resistance), WDZ- (low smoke halogen free, enterprise standard), TH- (hot and humid areas), FY- (termite prevention, enterprise standard) and so on.

4. Main content

1) SYV: solid polyethylene insulated radio frequency coaxial cable, coaxial cable, radio frequency signal transmission in wireless communication, broadcasting, monitoring system engineering and related electronic equipment (including comprehensive coaxial cable)
2) SYWV (Y) : physical foamed poly (B) insulated cable system cable, video (RF) coaxial cable (SYV, SYWV, SYFV) is suitable for closed-circuit monitoring and cable TV engineering
    SYWV (Y), SYKV cable TV, broadband network cable structure :(coaxial cable) single oxygen free round copper wire + physical foam polyethylene (insulation) + (tin wire + aluminum) + polyvinyl chloride (polyethylene)
3) Signal control cable (RVV sheath line, RVVP shielded line) is suitable for building intercom, anti-theft alarm, fire protection, automatic meter reading and other projects
    RVVP: Copper core PVC insulated shielded PVC sheathed flexible cable, voltage 250V/300V, 2-24 core Uses: instrument, meter, intercom, monitoring, control installatio
4) RG: physical foamed polyethylene insulated access network cable is used to transmit data analog signals in coaxial fiber hybrid network (HFC)
5) KVVP: PVC sheathed braided shielded cable, uses: electrical appliances, instruments, power distribution device signal transmission, control, measurement
6) RVV (227IEC52/53) : PVC insulated flexible cable, uses: household appliances, small power tools, instruments and power lighting
7) AVVR: PVC sheathed flexible cable for installation
8) SBVV: HYA data communication cable (indoor and external) is used for telephone communication and radio equipment connection and telephone distribution network distribution box wiring
9) RV, RVP: PVC insulated cable
10) RVS, RVB: suitable for household appliances, small power tools, instruments, meters and power lighting connection cables
11) BV, BVR: PVC insulated cable, use: suitable for electrical instrument equipment and power lighting fixed wiring
12) RIB: Speaker cable (RIB)
13) KVV: PVC insulated control cable, uses: electrical appliances, meters, power distribution device signal transmission, control, measurement
14) SFTP: twisted pair, transmission telephone, data and information network
15) UL2464: computer connection cable
16) VGA: monitor cable
17) SDFAVP, SDFAVVP, SYFPY: coaxial cable, special for elevator
18) JVPV, JVPVP, JVVP: copper core PVC insulated and sheathed copper wire, woven electronic computer control cable

Four, the main use of cable

Cables are mainly used for power supply; Transmission and distribution; Motors, electrical appliances and electrical instruments are wound around resistance to achieve electromagnetic energy conversion; Measuring electrical and physical parameters; Transmission of signals, information and control; For common antenna TV or cable TV systems; Used as a feed wire for transmitting and receiving antennas of radio stations or a connection wire for various radio frequency communication and test equipment.

Five, the main performance of the cable

1, electrical performance

Electrical CONDUCTIVITY - MOST products require good electrical conductivity, individual products require a certain resistance range.
Electrical insulation properties - insulation resistance, dielectric coefficient, dielectric loss, electrical resistance, etc.
Transmission characteristics -- refers to high frequency transmission characteristics, anti-interference characteristics, etc.

2. Aging performance

It refers to the ability of products and their constituent materials to maintain their original properties under the action of mechanical, electrical, thermal and other external factors, or under the action of external climatic conditions.

3. Thermal performance

Refers to the temperature resistance grade of the product, operating temperature heating and heat dissipation characteristics of electric power transmission cables, current carrying capacity, short circuit and overload capacity, thermal deformation and heat shock resistance of synthetic materials, thermal expansion of materials and dripping properties of impregnated or coated materials, etc.

4, corrosion resistance and climate resistance

Refers to resistance to electrochemical corrosion, biological and bacterial erosion, resistance to chemical drugs (oil, acid, alkali, chemical solvents, etc.) erosion, salt spray resistance, light resistance, cold resistance, mildew resistance and moisture resistance, etc.

5. Mechanical properties

Refers to tensile strength, elongation, bending, elasticity, softness, vibration resistance, abrasion resistance and mechanical force impact resistance.

6, other performance

This includes some material characteristics (such as hardness of metal materials, creep, compatibility of polymer materials) and some special use characteristics of the product (such as non-delay ignition, atomic radiation resistance, insect bite protection, delayed transmission, and energy damping, etc.).