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Basic Knowledge of Wires and Cables, Application Classification and Meaning of Letter Designations
创建于2025.11.14
Translation of Wires and Cables Terminology
There is no strict boundary between "wires" and "cables".
Typically, products with a small number of cores, small outer diameter, and simple structure are called wires. Those without insulation are referred to as bare wires, while others are called cables.
Conductors with a larger cross-sectional area (over 6 square millimeters) are known as large wires, and those with a smaller cross-sectional area (6 square millimeters or less) are called small wires. Insulated wires are also termed wiring cables.
II. Different Types of Cables
(1) Categories
- H – Urban communication cables
- HP – Distribution cables
- HJ – Central office cables
(2) Insulation
- Y – Solid polyolefin insulation
- YF – Foamed polyolefin insulation
- YP – Foam/solid-sheathed polyolefin insulation
(3) Inner Sheath
- A – Polyethylene sheath with plastic-coated aluminum tape bonded shielding
- S – Polyethylene sheath with aluminum-steel double-layer metal tape shielding
- V – Polyvinyl chloride (PVC) sheath
(4) Features
- T – Petroleum jelly filling
- G – High-frequency isolation
- C – Self-supporting type
(5) Outer Sheath
- 23 – Double-layer anti-corrosion steel tape armoring with polyethylene outer covering
- 33 – Single-layer fine steel wire armoring with polyethylene outer covering
- 43 – Single-layer thick steel wire armoring with polyethylene outer covering
- 53 – Single-layer corrugated steel tape longitudinal armoring with polyethylene outer covering
- 553 – Double-layer corrugated steel tape longitudinal armoring with polyethylene outer covering
III. Cable Model Codes
- Application Code
- Insulation Code
- Conductor Material Code
- Inner Sheath Code
- Derivative Code
- Outer Sheath Code
- Special Product Code
- Rated Voltage
IV. Cables for Different Purposes
- SYV
- SYWV(Y)
- RVVP
- RG
- KVVP
- RVV (227IEC52/53)
- AVVR
- SBVV, HYA
- RV, RVP
- RVS, RVB
- BV, BVR
- RIB
- KVV
- SFTP
- UL2464
- VGA
- SYV
- SDFAVP, SDFAVVP, SYFPY
- JVPV, JVPVP, JVVP
V. Armoring and Outer Sheath Numbers for Power Cables
- 0: None
- 1: Interlocked armoring with fiber outer covering
- 2: Double-layer steel tape with PVC outer covering
- 3: Fine round steel wire with polyethylene outer covering
- 4: Thick round steel wire
- 5: Corrugated (crimped) steel tape
- 6: Double aluminum (or aluminum alloy) tape
- 7: Copper wire braiding
- 8: Steel wire braiding
VI. Application Classification of Wires and Cables
1. Power Systems
The wire and cable products used in power systems mainly include: overhead bare wires, busbars (buses), power cables (plastic cables, oil-paper insulated power cables – mostly replaced by plastic power cables, rubber-sheathed cables, overhead insulated cables), branch cables (replacing some busbars), magnet wires, and wires/cables for electrical equipment in power systems.
2. Information Transmission Systems
Mainly include: telephone cables, TV cables, electronic cables, RF cables, optical fiber cables, data cables, magnet wires, power communication cables, and other composite cables.
3. Mechanical Equipment and Instrumentation Systems
Nearly all wire and cable products (except overhead bare wires) are used in this field, with a focus on power cables, magnet wires, data cables, and instrumentation cables.
VII. Product Classification of Wires and Cables
1. Bare Wires and Bare Conductor Products
Key features: Pure conductive metal, no insulation or sheath (e.g., aluminum-conductor steel-reinforced wires, copper-aluminum busbars, electric locomotive wires). Processing techniques mainly involve pressure processing (smelting, calendering, drawing, stranding/compacted stranding). Applications: Suburban and rural areas, main user lines, switch cabinets, etc.
2. Power Cables
Key features: Insulation layer extruded/wrapped around the conductor (e.g., overhead insulated cables); or multiple cores stranded (corresponding to phase wires, neutral wires, and ground wires in power systems – e.g., overhead insulated cables with 2+ cores); or additional sheath layers (e.g., plastic/rubber-sheathed wires and cables).Main technologies: Drawing, stranding, insulation extrusion (wrapping), cabling, armoring, sheath extrusion (process combinations vary by product).Applications: High-voltage power transmission in power generation, distribution, transmission, transformation, and supply lines; large current (tens to thousands of amps) and high voltage (220V to 500kV+).
3. Wires and Cables for Electrical Equipment
Key features: Diverse specifications and wide applications; most used at voltages ≤1kV; new products continuously developed for special scenarios (e.g., fire-resistant cables, flame-retardant cables, low-smoke halogen-free/low-smoke low-halogen cables, termite/mouse-proof cables, oil/cold/heat/wear-resistant cables, medical/agricultural/mining cables, thin-walled wires).
4. Communication Cables and Optical Fibers
Evolved from simple telephone/telegraph cables to multi-pair telephone cables, coaxial cables, optical fibers, data cables, and even composite communication cables. Features: Small and uniform structural dimensions, high manufacturing precision requirements.
5. Magnet Wires (Winding Wires)
Mainly used in various motors, instruments, and meters.
VIII. Specifications and Models of Wires and Cables
- RY: Polyethylene-insulated flexible wires
- BV: Copper-core PVC-insulated wires
- RV: Copper-core PVC-insulated flexible installation wires
- RV: Copper-core PVC-insulated connection cables (wires)
- BLV: Aluminum-core PVC-insulated wires
- BYR: Polyethylene-insulated flexible wires
- BVR: Copper-core PVC-insulated flexible wires
- BVS: Copper-core PVC-insulated twisted flexible wires
- RVB: Copper-core PVC-insulated flat connection flexible wires
- RYV: Polyethylene-insulated PVC-sheathed flexible wires
- BYVR: Polyethylene-insulated PVC-sheathed flexible wires
- BVV: Copper-core PVC-insulated PVC-sheathed wires
- BLVV: Aluminum-core PVC-insulated PVC-sheathed wires
- AVR: Tinned copper-core polyethylene-insulated flat connection flexible cables (wires)
- RVB: Copper-core PVC flat connection wires
- RVS: Copper-core PVC twisted connection wires
- RVV: Copper-core PVC-insulated PVC-sheathed round connection flexible cables
- ARVV: Tinned copper-core PVC-insulated PVC-sheathed flat connection flexible cables
- RVVB: Copper-core PVC-insulated PVC-sheathed flat connection flexible cables
- RV－105: Copper-core heat-resistant (105℃) PVC-insulated connection flexible cables
- AF－205, AFS－250, AFP－250: Tinned silver PVC-fluoroplastic insulated high-temperature-resistant (-60℃~250℃) connection flexible wires
IX. Meaning of Wire and Cable Specification Notation
Specifications are expressed using number of cores, nominal cross-sectional area, and voltage level.
1. Specification Notation for Single-Core Branch Cables
Number of cables in the same circuit × (1 × nominal cross-sectional area), 0.6/1kVExample: 4×(1×185)+1×95 0.6/1kV
2. Specification Notation for Multi-Core Stranded Branch Cables
Number of cables in the same circuit × nominal cross-sectional area, 0.6/1kVExample: 4×185+1×95 0.6/1kV
3. Explanation of Wire and Cable Specifications and Models
Notes:
- B (B) – The first "B" denotes wiring; the second "B" denotes glass fiber braiding.
- V (V) – The first "V" denotes polyethylene (plastic) insulation; the second "V" denotes polyethylene sheath.
- L (L) – Aluminum; no "L" denotes copper.
- F (F) – Composite.
- R – Flexible wire.
- S – Twisted pair.
- X – Rubber insulation.
Insulated Wires (Conductors) 〔1〕〔2〕〔3〕〔4〕〔5〕
- 〔1〕Code: B – Wire (sometimes omitted).
- 〔2〕Conductor: T – Copper core (default if omitted); L – Aluminum core; R – Flexible copper.
- 〔3〕Insulation: V – PVC; X – Rubber; F – Neoprene rubber.
- 〔4〕Sheath: V – PVC.
- 〔5〕Others: R – Flexible wire; P – Shielding; B – Flat; S – Twisted pair.
Examples:
- RVV3×2.5: 1 piece of 3-core sheathed wire
- RV3×2.5: 3 pieces of flexible wires
- BVR3×2.5: 3 pieces (of BVR wires)
- RVB2×2.5; RVS2×1.5: 1 piece of twisted pair wire
- BVV2×1.5; BVVB2×1.5
- RVVP: Currently used telephone wires
- Common wires: BV2.5mm² (for light switches); BV4mm² (for sockets); BLV2.5mm²
Meaning of Power Cable and Control Cable Models 〔1〕〔2〕〔3〕〔4〕〔5〕〔6〕〔7〕〔8〕〔9〕
- 〔1〕ZR – Flame-retardant; NH – Fire-resistant.
- 〔2〕Application: Unmarked for power cables; K – Control cables; P – Signal cables; DJ – Computer cables.
- 〔3〕Insulation Layer: V – PVC; Y – Polyethylene; YJ – Cross-linked polyethylene; X – Rubber; Z – Paper.
- 〔4〕Conductor: T – Copper core (default if omitted); L – Aluminum core.
- 〔5〕Inner Sheath: V – PVC; Y – Polyethylene; Q – Lead sheath; L – Aluminum sheath; H – Rubber; HF – Non-flammable rubber; LW – Corrugated aluminum sheath; F – Neoprene; N – Nitrile rubber sheath.
- 〔6〕Features: Unmarked for unitary sheathing; F – Split-phase lead sheath/split-phase sheath; D – Non-draining; CY – Oil-filled; P – Shielding; C – For dust collectors; Z – DC.
- 〔7〕Armoring Layer: 0 – None; 2 – Double steel tape (24 – Steel tape/thick round steel wire); 3 – Fine round steel wire; 4 – Thick round steel wire (44 – Double thick round steel wire). Note: "22" indicates armored cables.
- 〔8〕Outer Covering: 0 – None; 1 – Fiber layer; 2 – PVC sheath; 3 – Polyethylene sheath.
- 〔9〕Rated Voltage: Expressed as a number, unit: kV.
Examples:
- VV 3×150: Copper-core PVC-insulated PVC-sheathed power cable.
- VV22 5×16: Copper-core PVC-insulated PVC-sheathed armored power cable.
- YJV 4×120: Cross-linked polyethylene-insulated PVC-sheathed power cable (most commonly used).
- YJV —1KV—4×35+1×16: YJV = Copper-core cross-linked polyethylene-insulated PVC-sheathed power cable; 1KV = Rated voltage 1000V; 4×35+1×16 = 5-core cable (4 cores of 35mm² + 1 core of 16mm²).
Key Identifier to Distinguish Cables and Wires
- "B" indicates wires; "R" indicates flexible wires/flexible copper; "S" indicates twisted pairs.
Codes and Meanings for Wires and Cables
- K – Control cables
- V – PVC
- P – Copper wire braided shielding
- R – Flexible conductor structure
- Y – Polyethylene
- P2 – Copper tape shielding
- ZR – Flame-retardant cables
- YJ – Cross-linked polyethylene
- 22 – Steel tape armoring
- NH – Fire-resistant cables
- NH-ZR-YJS-C
: Fire-resistant flame-retardant power cables with cross-linked polyethylene insulation, low-smoke halogen-free flame-retardant thermoplastic polyolefin liner (or sheath).
- NH-ZR-YJS24-C
: Fire-resistant flame-retardant power cables with cross-linked polyethylene insulation, low-smoke halogen-free flame-retardant thermoplastic polyolefin liner (or sheath).
Control Cables
- KVV22: PVC-insulated PVC-sheathed steel tape armored control cables.
- KYJVP-ZR: Cross-linked polyethylene-insulated PVC-sheathed copper wire braided shielded flame-retardant control cables.
- KYJVP-NH: Cross-linked polyethylene-insulated PVC-sheathed copper tape shielded fire-resistant control cables.
Main Applications and Operating Characteristics
Suitable for control, monitoring circuits, and protection lines with rated voltage ≤450/750V.
- Long-term allowable operating temperature for cross-linked polyethylene (XLPE) insulated control cables: ≤90℃.
- Long-term allowable operating temperature for PVC-insulated/polyethylene-insulated control cables: ≤70℃.
- Minimum installation temperature: ≥0℃.
- Bending radius for copper tape shielded or steel tape armored cables: ≥12× cable outer diameter.
- Bending radius for other cable types: ≥6× cable outer diameter.
Meaning of Symbols in Power Cable Models
- T: Copper (usually omitted from models).
- L: Aluminum.
- V: PVC insulation or sheath.
- YJ: Cross-linked PVC insulation.
- 22: Steel tape armoring.
- 32: Fine steel wire armoring.
- 42: Thick steel wire armoring.
- R: Flexible cables (wires) for connection; flexible structure.
- B: Flat (shape).
- S: Twisted pair.
- A: Tinned or silver-plated.
- F: High-temperature resistant.
- P: Braided shielding.
- P2: Copper tape shielding.
- P22: Steel tape armoring.
- Y: Pre-formed (usually omitted); or polyolefin sheath.
- FD: Product category code for branch cables (to be specified in the upcoming Ministry of Housing and Urban-Rural Development standard as FZ, with the same essence).
- ZR: Flame-retardant type.
- ZRK: Series code for flame-retardant control cables (similar for other categories).
- NH: Fire-resistant type.
- WDZ: Low-smoke halogen-free flame-retardant type.
- WDN: Low-smoke halogen-free fire-resistant type.
Examples
- SYV 75-5-1 (A, B, C)
:S: RF; Y: Polyethylene insulation; V: PVC sheath; A: 64 strands; B: 96 strands; C: 128 strands; 75: 75 ohms; 5: Wire diameter 5mm; 1: Single core.
- SYWV 75-5-1
:S: RF; Y: Polyethylene insulation; W: Physical foaming; V: PVC sheath; 75: 75 ohms; 5: Cable outer diameter 5mm; 1: Single core.(Source: Power Transmission and Distribution Equipment Network)
- RVVP2×32/0.2; RVV2×1.0; BVR
:R: Flexible wire; VV: Double-sheathed wire; P: Shielding; 2: 2-core multi-strand wire; 32: 32 copper wires per core; 0.2: Diameter of each copper wire = 0.2mm.
- ZR-RVS 2×24/0.12
:ZR: Flame-retardant; R: Flexible wire; S: Twisted pair; 2: 2-core multi-strand wire; 24: 24 copper wires per core; 0.12: Diameter of each copper wire = 0.12mm.
Models and Names
- RV: Copper-core PVC-insulated connection cables (wires)
- AVR: Tinned copper-core polyethylene-insulated flat connection flexible cables (wires)
- RVB: Copper-core PVC flat connection wires
- RVS: Copper-core PVC twisted connection wires
- RVV: Copper-core PVC-insulated PVC-sheathed round connection flexible cables
- ARVV: Tinned copper-core PVC-insulated PVC-sheathed flat connection flexible cables
- RVVB: Copper-core PVC-insulated PVC-sheathed flat connection flexible cables
- RV－105: Copper-core heat-resistant (105℃) PVC-insulated connection flexible cables
- AF－205, AFS－250, AFP－250: Tinned silver PVC-fluoroplastic insulated high-temperature-resistant (-60℃~250℃) connection flexible wires
Meaning of Specification Notation
Specifications are expressed using number of cores, nominal cross-sectional area, and voltage level.
① Single-core branch cables: Number of cables in the same circuit × (1 × nominal cross-sectional area), 0.6/1kVExample: 4×(1×185)+1×95 0.6/1kV (Source: http://tede.cn)
② Multi-core stranded branch cables: Number of cables in the same circuit × nominal cross-sectional area, 0.6/1kVExample: 4×185+1×95 0.6/1kV
③ Multi-core same-sheath branch cables: Number of cable cores × nominal cross-sectional area - TExample: 4×25-T
Complete Specification and Model Notation
Branch cables include main cables and branch cables, which differ in specifications and structure. Two notation methods are used:
① Separate notation for main and branch cablesExample:
- Main cable: FD-YJV-4×(1×185)+1×95 0.6/1kV
- Branch cable: FD-YJV-4×(1×25)+1×16 0.6/1kV
② Combined notation for main and branch cablesExample: FD-YJV-4×(1×185/25)+1×95/16 0.6/1kVThis method is intuitive but only applies when all branches have the same specification (cannot indicate different branch specifications).
Since branch cables are mainly used in 1kV low-voltage power distribution systems, their rated voltage (0.6/1kV) can be omitted in design labels.
II. Meanings of Pinyin Letters in Product Models (Unbracketed Characters)
- A: (Poly)amide, (A)installation, (Al)peth (aluminum-plastic sheath)
- B: (B)flat, (B)half, (B)raided, (B)ump, (B)raided, (Poly)styrene, (B)orosilicate fiber, (B)acking, (B)parallel
- C: (C)ar, (C)arbinol, (C)onstruction machinery, (C)eramic, (C)heavy-duty, (C)shipboard, (C)battery, (C)magnetic charging, (C)ompensation, (C)ambric, (C)ellulose triacetate film, (C)self-supporting
- D: (D) tape, (D) rip-proof, (D) lamp, (D) electric, (D) freezing (cold-resistant), (D) butyl rubber, (D) 镀 (plated)
- E: (E)double-layer, (E)external (outdoor), (E)symmetrical structure (code), (E)thylene-propylene rubber (EPR)
- F: (F)luoropolymer (PTFE), (F)ractional phase, (F)lame-retardant, (F)light (aircraft), (F)oamed polyethylene (YF)
- G: (G)steel, (G)roove, (G)modified paint, (G)tube, (G)high-voltage
- H: (H)alloy, (H)epoxy paint, (H)elding, (H)igh-frequency, (H)communication cable (application code), (H)-type (split-phase shielding structure), (H)cold-resistant
- J: (J)twisted, (J)reinforced, (J)thickened, (J)sawing, (J)central office (use)
- K: (K) vacuum, (K) apron, (K) ontrol (control), (K) 铠装 (armored), (K) hollow
- L: (L)aluminum, (L)furnace, (L)acquer, (L)asphalt, (L)ightning-proof, (L)phosphorus
- M: (M)ercury, (M)ineral, (M)other (busbar), (M)cap, (M)embrane
- N: (N)self-adhesive, (N)peat, (N)high-resistance nickel (core), (N)ylon, (N)on-flammable (fire-resistant)
- O: (O)coaxial (structure code)
- P: (P)ower distribution, (P)core shielding, (P)wiring, (P)oorly impregnated (dry insulation), (P)signal cable (application code)
- Q: (Q)traction (vehicle), (Q)paint, (Q)lead, (Q)lightweight, (Q)gas, (Q)automotive, (Q)high-strength polyvinyl acetal
- R: (R)flexible, (R)ayon, (R)domestic (application code), (R)heat-resistant
- S: (S)brush, (S)ilk, (S)ignal (RF, application code), (S)double, (S)talpeth (steel-plastic sheath), (S)moke-free halogen-free flame-retardant sheath
- T: (T)copper, (T)rapezoidal, (T)special, (T)general, (T)ceramic, (T)elevator, (T)esting
- U: (U)mining, (U)minal (asbestos), (U)mining (application code)
- V: (P)V(C) (polyvinyl chloride)
- W: (W)ireless (geophysical), (W)rinkled sheath, (W)ireless (non-magnetic), (W)ear-resistant, (W)ild (outdoor), (W)ell (oil, application code)
- X: (X)rubber (power cable), (X)polyamide, (X)rubber insulation
- Y: (Y)hard, (Y)round, (Y)oil, (Y)oxygen, (Y)oil-resistant, (Y)mobile (application code), (Y)polyethylene, (Y)pressure
- Z: (Z)polyester, (Z)paper, (Z)drill, (Z)medium-sized, (Z)comprehensive
Cable Models Consist of Eight Parts
- Application Code – Unmarked for power cables; K for control cables; P for signal cables.
- Insulation Code – Z for oil-impregnated paper; X for rubber; V for PVC; YJ for cross-linked polyethylene.
- Conductor Material Code – Unmarked for copper; L for aluminum.
- Inner Sheath Code – Q for lead sheath; L for aluminum sheath; H for rubber sheath; V for PVC sheath.
- Derivative Code – D for non-draining; P for dry insulation.
- Outer Sheath Code
- Special Product Code – TH for humid tropical regions; TA for dry tropical regions.
- Rated Voltage – Unit: kV
Issues Related to Cable Models
1. SYWV (Y), SYKV Cables for Cable TV and Broadband Networks
Structure (Coaxial Cable): Single oxygen-free round copper wire + physical foamed polyethylene (insulation) + (tin wire + aluminum) + polyvinyl chloride (or polyethylene).
2. Signal Control Cables (RVV Sheathed Cables, RVVP Shielded Cables)
Suitable for projects such as building intercom systems, anti-theft alarms, fire protection, and automatic meter reading.
3. RVVP Flexible Cable with Copper Core, PVC Insulation, Shielding, and PVC Sheath
- Voltage:
- Number of Cores:
- Applications:
4. KVVP Braided Shielded Cable with PVC Sheath
- Applications:
5. RVV (227IEC52/53) Flexible PVC-Insulated Cable
- Applications:
6. RV PVC-Insulated Cable
7. RVS, RVB Cables
Suitable for connecting household appliances, small electric tools, instruments, meters, and power lighting systems.
8. BV, BVR PVC-Insulated Cables
- Applications:
9. KVV PVC-Insulated Control Cable
- Applications:
Differences Between Cables
Cable Pair | Differences |
RVV & KVV | RVV uses flexible wires composed of multiple fine copper strands (i.e., RV wires); KVV uses rigid wires composed of single thick copper strands (i.e., BV wires). |
RVVP & KVVP | RVVP uses flexible wires composed of multiple fine copper strands (i.e., RV wires); KVVP uses rigid wires composed of single thick copper strands (i.e., BV wires). |
AVVR & RVVP | They are essentially the same product. Cables with an internal cross-section < 0.75 mm² are named AVVR; those with ≥ 0.75 mm² are named RVVP. |
SYV & SYWV | SYV is a video transmission cable with polyethylene insulation; SYWV is a radio frequency transmission cable with physical foamed insulation, used for cable TV. |
RVS & 2-Core RVV | RVS is formed by twisting two RV cores (no outer sheath), used for broadcast connections; 2-core RVV is cabled in a straight layout (with outer sheath), used for power supply and control signals. |
Definitions of Common Abbreviations in Cable Models
- R
- V
- B
- S
- A
- F
- P
- Y
- FD
- YJ
- ZR
- NH
- WDZ
- WDN
Representation Methods (Specifications, Models) for Common Cables, Wires, and Network Cables
I. Definitions of Common Abbreviations
- R
- V
- B
- S
- A
- F
- P
- Y
- FD
- YJ
- ZR
- NH
- WDZ
- WDN
II. General Definitions of Abbreviations
Abbreviation | Definitions |
A | Amine (resin), Installation, Aluminum-polyethylene sheath (Alpeth) |
B | Flat, Semi-, Braided, Pump, Cloth, Polystyrene, Glass fiber, Supplementary, Parallel |
C | Automotive, Alcohol, Mining machine, Ceramic, Heavy-duty, Marine, Battery, Magnetic charging, Compensation, Yellow waxed silk, Triacetate film, Self-supporting |
D | Tape, Non-dripping, Lamp, Electrical, Cold-resistant, Butyl rubber, Plated |
E | Double-layer, Outdoor, Symmetrical structure (code), Ethylene-propylene rubber (EPR) |
F | Polytetrafluoroethylene (PTFE), Split-phase, Non-flammable, Aircraft, Foamed polyethylene (YF) |
G | Steel, Trench, Modified paint, Pipe, High-voltage |
H | Alloy, Epoxy paint, Welding, Spark, Communication cable (application code), H-type (split-phase shielding structure), Cold-resistant |
J | Stranded, Reinforced, Thickened, Sawing, Office-use |
K | Vacuum, Kapron, Control, Armored, Hollow |
L | Aluminum, Furnace, Lacquer, Asphalt, Lightning-proof, Phosphorus |
M | Cotton yarn, Hemp, Busbar, Cap, Membrane |
N | Self-adhesive, Peat, High-resistance nylon (core), Nylon, Fire-resistant |
O | Coaxial (structure code) |
P | Row, Core shielding, Wiring, Poor impregnation (dry insulation), Signal cable (application code) |
Q | Tractor, Paint, Lead, Light-duty, Pneumatic, Automotive, High-strength polyvinyl acetal |
R | Flexible, Rayon, Daily-use (application code), Heat-resistant |
S | Brush, Wire, Radio frequency (application code), Double, Steel-polyethylene sheath (Stalpeth), Halogen-free low-smoke flame-retardant sheath |
T | Copper, Ladder, Special, General, Ceramic, Elevator, Detection |
U | Mining, Asbestos (cotton), Mining-use (application code) |
V | PVC (polyvinyl chloride) |
W | Geophysical, Corrugated sheath, Non-magnetic, High-temperature resistant, Outdoor, Petroleum (application code) |
X | Rubber (power cable), Polyamide, Rubber insulation |
Y | Rigid, Round, Oil, Oxygen, Oil-resistant, Mobile (application code), Polyethylene, Compressed |
Z | Polyester, Paper, Electric drill, Medium-sized, Comprehensive |
YJ | Cross-linked polyethylene insulation |
P2 | Copper tape shielding |
ZRK | Series code, indicating flame-retardant control cables |
III. Cable Basics
Cables are usually divided into power cables and control cables.
1. Meanings of General Cable Symbols
No. | Symbol Category | Meanings |
1 | Flame-retardant/Fire-resistant | ZR = Flame-retardant; NH = Fire-resistant; ZA(IA) = Intrinsically safe |
2 | Application | Power cables: No default symbol; K = Control cables; P = Signal cables; DJ = Computer cables |
3 | Insulation Layer | V = PVC; Y = Polyethylene; YJ = Cross-linked polyethylene; X = Rubber; Z = Paper |
4 | Conductor | T = Copper core (default, omitted); L = Aluminum core |
5 | Inner Sheath | V = PVC; Y = Polyethylene; Q = Lead-sheathed; L = Aluminum-sheathed; H = Rubber; HF = Non-flammable rubber; LW = Corrugated aluminum sheath; F = Neoprene; N = Nitrile rubber sheath |
6 | Features | No symbol for general type; F = Split-phase lead-sheathed/split-phase sheathed; D = Non-dripping; CY = Oil-filled; P = Shielded; C = For dust collectors; Z = DC |
7 | Armoring Layer | 0 = None; 2 = Double steel tape (24 = Steel tape, thick round steel wire); 3 = Fine round steel wire; 4 = Thick round steel wire (44 = Double thick round steel wire) |
8 | Outer Sheath | 0 = None; 1 = Fiber layer; 2 = PVC sheath; 3 = Polyethylene sheath |
9 | Rated Voltage | Expressed in numbers, unit: kV |
2. Examples of Common Cables
- VV
- VV22
- YJV
3. Meanings of Specification Representation
Specifications are expressed by number of cores, nominal cross-section, and voltage level.
Type of Cable | Specification Expression Example |
Single-core branch cable | Number of cables in the same circuit * (1 * Nominal cross-section), 0.6/1KV E.g., 4*(1*185)+1*95 0.6/1KV |
Multi-core stranded branch cable | Number of cables in the same circuit * Nominal cross-section, 0.6/1KV E.g., 4*185+1*95 0.6/1KV |
Multi-core same-sheath branch cable | Number of cable cores × Nominal cross-section - T E.g., 4×25-T |
4. Complete Model-Specification Representation
Branch cables include main cables and branch cables, with different specifications. Two representation methods are used:
- Separate representation for main and branch cables:
- Combined representation for main and branch cables:
Since branch cables are mainly used in 1KV low-voltage power distribution systems, the rated voltage (0.6/1KV) can be omitted in design labels.
5. Tips for Calculating Wire Diameter of 5-Core Cables
The cross-section of 4 phase/ground wires is twice that of 1 protective ground wire.
- E.g., 4*185+1*95 (185/2 = 92.5, rounded up to 95)
- E.g., 4*95+1*50 (95/2 = 47.5, rounded up to 50)
- E.g., 4*50+1*25 (50/2 = 25, directly taken as 25)
Supplementary Knowledge: Single-core cable cross-section specifications (unit: mm²): 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400.
6. Rhyming Formula for Cable Current-Carrying Capacity
(Applicable to copper-core wires/cables)
- "Below 10, multiply by 5" → For cross-sections ≤10 mm²: Current-carrying capacity = Cross-section × 5 (e.g., 10 mm² cable carries 50 A).
- "Above 100, multiply by 2" → For cross-sections ≥100 mm²: Current-carrying capacity = Cross-section × 2.
- "25/35, 4 and 3" → 25 mm²: ×4; 35 mm²: ×3.
- "70/95, two and a half" → 70 mm² and 95 mm²: ×2.5.
IV. Wire Basics
1. Meanings of General Wire Symbols
No. | Symbol Category | Meanings |
1 | Code | B = Wire (sometimes omitted) |
2 | Conductor | T = Copper core (default, omitted); L = Aluminum core; R = Flexible copper |
3 | Insulation | V = PVC; X = Rubber; F = Neoprene |
4 | Sheath | V = PVC |
5 | Others | R = Flexible wire; P = Shielded; B = Parallel |
2. Examples of Common Wires
Model | Description & Applications |
BX, BLX | Rubber-insulated wires. Fixed installation indoors/outdoors (exposed, concealed, or in pipes) for equipment wiring. |
BXF, BLXF | Neoprene-insulated wires. Same as BX type, with better weather resistance; suitable for outdoor use. |
BXR | Flexible rubber-insulated wires. Same as BX type; only used in locations requiring flexibility during installation. |
BXHF, BXLHF | Rubber-insulated and sheathed wires. Same as BX type; suitable for humid environments and as outdoor service entrance wires. |
BV, BLV | PVC-insulated wires. Same as BX type, with better moisture and weather resistance. |
BVR | Flexible PVC-insulated wires. Same as BV type; only used in locations requiring flexibility during installation. |
BVV, BLVV | PVC-insulated and sheathed wires. Same as BV type; used in humid environments and locations with high mechanical protection requirements (can be directly buried in soil). |
BV-105, BLV-105 | 105℃ heat-resistant PVC-insulated wires. Same as BV type; used in high-temperature environments (≥45℃). |
BVR-105 | 105℃ heat-resistant flexible PVC-insulated wires. Same as BVR type; used in high-temperature environments (≥45℃). |
RV | Single-core flexible PVC-insulated copper wire. For wiring of mobile electrical appliances, meters, telecommunications equipment, and automation devices; also used for internal installation (ambient temperature ≥-15℃ during installation). |
AVR | Tinned copper-core PVC-insulated flat flexible connecting wire. |
RVB | 2-core flat flexible PVC-insulated copper wire. Same application as RV (ambient temperature ≥-15℃ during installation). |
RVS | 2-core twisted flexible PVC-insulated copper wire. Same application as RV (ambient temperature ≥-15℃ during installation). |
RVV | Round flexible PVC-insulated PVC-sheathed copper wire. Same as RV type; used in humid environments, locations with high mechanical protection requirements, and scenarios requiring frequent movement/bending. |
ARVV | Tinned copper-core PVC-insulated PVC-sheathed flat flexible connecting wire. |
RVVB | Copper-core PVC-insulated PVC-sheathed flat flexible connecting wire. |
RV-105 | 105℃ heat-resistant flexible PVC-insulated copper wire. |
AF-205, AFS-250, AFP-250 | Silver-plated PVC-fluoroplastic insulated high-temperature resistant flexible wires (-60℃~250℃). |
RFS (2-core twisted), RFB (2-core flat) | Nitrile-PVC composite insulated flexible wires. Same as RVB/RVS type, with better low-temperature flexibility. |
RXS (RXB), RX | Cotton-braided rubber-insulated twisted (flat) flexible wires / Cotton-braided rubber-insulated flexible wires. Power cords for indoor household appliances and lighting. |
3. Meanings of Specification Representation
- RVVP2*32/0.2
- ZR-RVS2*24/0.12
4. Specifications & Sizes of BV, BLV, BVV
- BV
- BLV
- BVV
V. Knowledge of Video Transmission Materials (e.g., Cable TV)
Video signal transmission cables mainly include coaxial cables, twisted pairs, and optical fibers. Below is an introduction to common coaxial cables:
1. Classification of Coaxial Cables for Video Transmission
SYV75-3, SYV75-5, SYV75-7, SYV75-9, SYV75-12
2. Meanings of Abbreviations (Taking SYV75-5-1(A, B, C), SYV75-5-41(A, B, C), SYV75-5-2(A, B, C) as Examples)
- S
- Y
- V
- 75
- 5
- -1, -41, -2
- A/B/C
VI. Knowledge of Network Cables
Common name: Cat5 Cable
1. Classification of Network Cables
By electrical performance, twisted pairs are usually divided into: Cat3, Cat4, Cat5, Cat5e, Cat6, Cat7, etc. In principle, a higher number indicates a newer version, more advanced technology, wider bandwidth, and a higher price.
- Selection Recommendations
: For LANs, Cat5 or Cat5e is generally used. Cat3/Cat4 are mainly for 10 Mbps Ethernet; Cat5 meets the needs of 100 Mbps Ethernet (now popular); Cat5e is mainly for future Gigabit networks but is also widely used in current LANs (slightly more expensive than Cat5). Cat6 is generally for ATM networks and is not recommended for corporate LANs for now.
- Market Note
: Cat3/Cat4 are almost obsolete; if available, they are often mislabeled as Cat5 or Cat5e (a common form of counterfeit Cat5 cables).
- Common Types in LANs
: Cat5, Cat5e, or Cat6 unshielded twisted pairs (UTP). Especially Cat5e and Cat6 UTP can easily provide 155 Mbps bandwidth and have the potential to upgrade to Gigabit speeds, making them the first choice for current horizontal cabling.
- Basic Composition
: Twisted pairs consist of twisted wires of a certain length and RJ45 connectors (水晶头，"crystal heads"). Most LANs use UTP as the transmission medium for networking.
2. Representation of Network Cables
- Cat5: Marked as "cat5"
- Cat5e: Marked as "cat5e"
- Cat6: Marked as "cat6"
3. Wiring Standards for RJ45 Connectors
(1) Wiring Standards
- T568A Standard
- T568B Standard
(2) General Principles for Wiring
- Same Device (Both Ends Are the Same Equipment)
- Different Devices (Both Ends Are Different Equipment)
(3) Wiring Tips
When making an RJ45 connector:
- Face the connector’s latch outward and the wire inlet downward.
- Arrange the wires in the above sequence from left to right.
- Insert the wires fully (ensure the copper cores of the twisted pairs are visible at the top of the connector).
- Crimp with a network cable crimper.
4. Introduction to Hubs (Commonly Called "Hub")
(1) Overview
The English term for a hub is "Hub" (meaning "center"). Its main functions are to regenerate, reshape, and amplify received signals to extend the network transmission distance, and to concentrate all nodes on the node centered on itself.
- OSI Layer
- Classification
(2) Differences Between Hubs and Switches
Feature | Hub | Switch |
Hardware Nature | Pure hardware 底层 (bottom-layer) network device | Has "intelligent memory" and "learning" capabilities |
MAC Address Table | Does not have a MAC address table | Has a MAC address table |
Data Transmission Mode | Broadcast (sends data to all connected nodes, not targeted) | Targeted transmission (sends data only to the destination node) |
Security | Low (data is broadcast to all nodes, easy to intercept illegally) | High (targeted transmission reduces interception risks) |
Network Efficiency | Low (broadcast + shared bandwidth easily causes network congestion) | High (avoids broadcast storms and shared bandwidth issues) |
Transmission Mode | Half-duplex (only one direction of data communication per port at a time) | Full-duplex (bidirectional simultaneous data communication per port) |
(3) Application Scenarios
Despite its limitations, hubs are still economically attractive for homes or small businesses—especially suitable for home networks with a few devices or as branch networks in small/middle-sized companies.
(4) Classification by Signal Processing
- Passive Hub
- Active Hub
- Intelligent Hub