The line professional maintenance training manual mainly includes eight parts of content: basic knowledge, maintenance projects, maintenance cycles and standards, maintenance evaluation indicators, maintenance management systems and processes, maintenance operation standards and steps, instrument usage, emergency response plan principles, and typical fault cases. It also contains some product introductions and test questions.
### Part One: Basic Knowledge
#### 1. Fiber Classification
Based on the number of transmission modes, fibers are divided into multimode fiber and single-mode fiber:
- Single-mode fibers, according to ITU (International Electrotechnical Commission) standard specifications, are further classified into four types: G.652, G.653, G.654, and G.655 single-mode fibers.
- **G.652 Fiber**: Also known as standard single-mode fiber (SMF), it refers to fibers with a zero-dispersion point (the wavelength where dispersion is zero) around 1310nm.
- **G.653 Fiber**: Also called dispersion-shifted fiber (DSF), it refers to fibers with a zero-dispersion point around 1550nm. Compared to G.652 fibers, the zero-dispersion point has shifted, hence the name "dispersion-shifted fiber."
- **G.654 Fiber**: This is a cutoff-wavelength-shifted single-mode fiber. Its design focus is on reducing attenuation at 1550nm, while its zero-dispersion point remains near 1310nm. Thus, the dispersion in the 1550nm window is relatively high. G.654 fibers are primarily used in submarine optical communications.
- **G.655 Fiber**: Since the zero-dispersion point of G.653 fibers is near 1550nm, DWDM systems working at this wavelength are prone to four-wave mixing effects. To avoid this effect, the zero-dispersion point is shifted away from the DWDM working wavelength range around 1550nm. Such fibers are non-zero dispersion-shifted fibers (NDSF).
#### 2. Optical Cable Classification
Below, we will focus on the classification of optical cables by their core structure. Optical cables can be divided into four major categories based on their core structure: stranded optical cable, skeleton optical cable, bundle tube optical cable (central tube type), and ribbon optical cable, as shown in Figure 1.4.
- **Stranded Optical Cable**: Tight-buffered or loose-tube fibers are helically stranded around a central reinforcing component. Compared to central tube optical cables, the production process and equipment for stranded optical cables are relatively more complex. They can have a higher number of fiber cores (up to 144 cores), and the excess length of the fibers within the cable is easier to control.
- **Skeleton Optical Cable**: Primary-coated or secondary-coated tight-buffered fibers are placed into skeleton grooves to form an optical cable. The production process and equipment for skeleton optical cables are relatively complex because there is an additional production line for the skeleton itself. Skeleton optical cables typically have up to 12 fiber cores.
- **Central (Bundle) Tube Optical Cable**: Loose-tube fibers (single-core or multi-core) are placed directly in the center position of the optical cable without any twisting. This position is most beneficial for reducing losses caused by cable bending. The reinforcement components can either be two parallel high-carbon steel wires placed parallel to the central tube inside the outer jacket (black polyethylene), or multiple low-carbon steel wires spirally wound around the central tube.
- **Ribbon Optical Cable**: Ribbon optical cables consist of 4 to 12 fiber cores arranged in rows to form a ribbon unit, and multiple ribbon units are then cabled together in a certain arrangement. This type of optical cable has a compact structure and can be made into high-density user optical cables with over a thousand cores using this structure.
#### Optical Cable Type Composition
Optical cable types are composed of five parts:
- **I: Classification Code and Meaning**:
- GY: Outdoor communication optical cable;
- GR: Flexible communication optical cable;
- GJ: Indoor communication optical cable;
- GS: Equipment internal communication optical cable;
- GH: Submarine communication optical cable;
- GT: Special communication optical cable.
- **II: Reinforcement Component Code and Meaning**:
- No symbol: Metal reinforcement component;
- F: Non-metal reinforcement component;
- G: Heavy-duty metal reinforcement component;
- H: Heavy-duty non-metal reinforcement component.
- **III: Derived Feature Code and Meaning**:
- D: Fiber ribbon structure;
- G: Skeleton groove structure;
- B: Flat structure;
- Z: Self-supporting structure;
- T: Filled structure.
- **IV: Sheath Code and Meaning**:
- Y: Polyethylene sheath;
- V: Polyvinyl chloride sheath;
- U: Polyurethane sheath;
- A: Aluminum-polyethylene bonded sheath;
- L: Aluminum sheath;
- G: Steel sheath;
- Q: Lead sheath;
- S: Steel-aluminum-polyethylene composite sheath.
- **V: Outer Sheath Code and Meaning**:
- The outer sheath refers to the armor layer and the outer sheath outside the armor. The code and meaning of the outer sheath are shown in Table 2.
#### Optical Cable Color Spectrum
Optical cable color spectra are divided into red-green leader colors and full color spectra:
- **Red-Green Leader Color Spectrum**: Starting with red-green tubes, the white tubes are divided clockwise into white tube 1, white tube 2, etc.
- **Fiber Color Spectrum**: Blue, orange, green, brown, gray, white, red, black, yellow, purple, pink, aqua green.
- Blue 1, 12-core.
### Three, Cables
Commonly used all-plastic cable model readings:
- HYA: Copper core solid polyolefin insulated aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYFA: Copper core foam polyolefin insulated aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYPA: Copper core foam skin polyolefin insulated aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYAT: Copper core solid polyolefin insulated filled aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYFAT: Copper core foam polyolefin insulated aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYPAT: Copper core foam skin polyolefin insulated aluminum-plastic bonded comprehensive sheath indoor communication cable.
- HYPAT23: Copper core foam/solid skin polyethylene (polyolefin) insulated, petroleum jelly filled, plastic-coated aluminum tape bonded shielding polyethylene sheath, double-layer corrosion-resistant steel tape wrapped armored outer sheath, indoor communication cable.
- HYAC: Copper core solid polyethylene (polyolefin) insulated, plastic-coated aluminum tape bonded shielding polyethylene sheath, self-supporting indoor communication cable.
- HYV: Copper core solid polyethylene insulated, polyvinyl chloride sheath aluminum foil wrapped tape, indoor communication cable.
- HJVVP: Copper core polyvinyl chloride insulated, polyvinyl chloride sheath, aluminum foil tape wrapped, indoor use communication cable.
#### Common All-Plastic Cable Specification Code Meaning
The specification code for commonly used all-plastic cables is usually placed after the cable model and represented by numbers.
For star-twisted cables, the sequence is:
- Number of star-twisted groups × Number of conductors per group × Conductor diameter (mm)
- Example: 50×4×0.5 = 100-pair cable.
For pair-twisted cables, the sequence is:
- Number of conductor pairs × Number of conductors per pair × Conductor diameter (mm)
- Example: 100×2×0.5 = 100-pair cable.
### Four, Pipes
1. Double-wall corrugated plastic pipes, with pipe outer diameters generally ranging from 100~110mm (can be produced according to needs), single piece length of 6 meters, widely used for main and distribution pipelines in urban areas, bridge main pipeline construction, etc.
2. Silicon-core plastic pipes, with inner walls coated with a silicon layer for smoothness, small friction coefficient, widely used as protective pipes for optical cables. Silicon-core pipe outer diameters range from 32~60mm, each piece can be up to 2000 meters long.
3. Multi-hole pipes (single holes are circular or hexagonal), produced as a multi-hole integrated structure, evenly stressed, compact structure. Pipe holes range from 3~7, single pipe outer diameter normally ranges from 25~32mm, can be combined arbitrarily according to needs. Pipe material length is generally over 6 meters, coiled ones can reach up to 200 meters, and can be produced according to needed lengths.
4. Honeycomb pipes (single holes are pentagonal or circular), produced as a multi-hole integrated structure, evenly stressed, compact structure. Pipe holes range from 3~7, single pipe outer diameter normally ranges from 25~32mm, can be combined arbitrarily according to needs. Pipe material length is generally over 6 meters. Usage scope should meet the requirements of multi-hole pipes.
5. Grating pipes (single holes are square), can be combined into different hole diameters and different hole numbers in square or rectangular shapes according to needs. Single pipe diameter can range from 28~90mm, can be combined arbitrarily according to needs. Pipe material length is generally over 6 meters. Application scope is the same as multi-hole pipes.
6. For pipe selection, for newly built roads in urban areas, cement pipes should be the first choice; for roads in urban areas with various comprehensive pipelines and complex terrain, plastic pipes should be selected; for dedicated pipelines used for optical cable construction, plastic pipes should be selected, and the number of holes and hole combinations should be chosen according to usage needs.
### Five, Poles
1. **Poles**
- Poles are generally Ф15cm tip diameter, 1/75 taper pre-stressed concrete poles, with a base pole height of 8m. Special section poles follow the construction diagram design regulations.
Pole burial depth requirements are shown in Table 12:
```
Table 12: Pole Burial Depth Requirements
Pole Height Application Burial Depth (m)
General Soil Hard Soil Waterlogged Field Stone Soil
7m x 15cm Rural Lines 1.3 1.2 1.4 1.0
8m x 15cm City, Long-distance Lines 1.5 1.4 1.6 1.2
9m x 15cm Road, River Lines 1.6 1.5 1.7 1.4
10m x 15cm Road, River Lines 1.7 1.6 1.8 1.6
12m x 15cm Road, River Lines 2.1 2.0 2.2 2.0
```
#### Guy Wires
1. Selection of Guy Wire Specifications:
- Terminal pole guy wire: Should select one level higher than the suspended wire (7/2.2) specification (7/2.6).
- Corner pole guy wire: When corner depth ≤13m, the guy wire matches the suspended wire specification; when corner depth >13m, one level higher than the suspended wire specification should be selected.
- Intermediate rod guy wire: If the load on both sides of the intermediate rod is different, a top guy wire should be set, and the top guy wire specification should match the larger side of the suspended wire.
- Wind-resistant rods' side guy wires, anti-icing rods' side guy wires, and in-line guy wires should all match the suspended wire specification.
- Fake terminals, force-relief joints, long rod distances, and high pull stakes with corner depths >3m should have guy wire specifications matching the suspended wire specifications.
- Support rod requirements: Consider the bending resistance at the point where the pole is stressed. When the corner depth >5m, the pole strength should be one level stronger than usual, and the corner depth should be <10m. The support rod's height-to-length ratio is generally 0.6, and the tip diameter of the support rod should not be less than 4/5 of the connected pole diameter.
#### Overhead Suspension Wire
Overhead optical cables are preferably hung using additional suspension wires, and each suspension wire generally only supports one optical cable. Based on engineering requirements, self-supporting methods may also be used. Optical cables can be installed on suspension wires using cable hooks or spiral binding.
#### Selection of Suspension Wire Specifications
In Jiangsu Province, overhead optical cable lines belong to light and medium load areas, and the standard pole spacing is generally 50m.
- 7/2.2 gauge galvanized steel strand: Used for optical cables.
- 7/2.2 gauge galvanized steel strand: Used for cables under 200 pairs.
- 7/2.6 gauge galvanized steel strand: Used for cables between 200-400 pairs.
- 7/3.0 gauge galvanized steel strand: Used for cables between 400-800 pairs.
#### Hooks
Hook specifications: Preferably use 25mm plastic hook or 25mm nylon board hook, do not use metal board hooks.
- 25mm: Used for 50 pairs or less (0.4mm line diameter).
- 35mm: Used for 100 pairs (0.4mm line diameter).
- 45mm: Used for 200 pairs (0.4mm line diameter).
- 55mm: Used for 300 pairs or more (0.4mm line diameter).
- 65mm: Used for 400 pairs or more (0.4mm line diameter).
#### Hook Spacing: 50±3cm