In mine power supply systems, high-voltage power lines typically use armored cables, which have a significantly lower failure rate compared to low-voltage systems. However, the power supply in mining areas is often a weak point in the overall system due to harsh working conditions. As a result, selecting the appropriate cable type and cross-sectional area is crucial for ensuring safe and reliable power operations. This article discusses the methods for selecting suitable cables and determining their cross-sectional dimensions.
Choosing the right cable model involves considering factors such as power supply reliability, safety, and economic efficiency. According to Article 467 of the Coal Mine Safety Regulations, the following guidelines must be followed when selecting cables:
1. The actual laying location's elevation difference should match the cable's allowable level difference.
2. Cables must have conductors with sufficient cross-section for protective earthing.
3. Aluminum-coated cables are strictly prohibited.
4. Flame-retardant cables that have passed inspection and obtained the required safety certification for coal mine products must be used.
5. The main core section of the cable must meet the load requirements of the power line.
6. Specific requirements for fixed high-voltage cable installation:
- In shafts or inclined tunnels with angles over 45°, PVC-insulated heavy steel wire armored cables or cross-linked polyethylene insulated thick steel wire armored cables with PVC sheathing should be used.
- In horizontal tunnels or shafts with inclinations of 45° or less, PVC-insulated steel tape or fine steel wire armored PVC-sheathed cables should be applied.
- Aluminum-core cables may be used between inclined shafts in intake areas, underground depots, and central substations, but copper-core cables are required elsewhere.
- Fixed low-voltage cables should be either M-type or non-armored cables, or mobile rubber-sheathed cables of the corresponding voltage class.
- Non-fixed high- and low-voltage cables must use rubber cables conforming to the MR818 standard. Mobile and handheld electrical equipment should use dedicated rubber-sheathed cables.
- Cables for lighting, communication, signaling, and control should use armored telecommunication cables, rubber-sheathed cables, or factory-type plastic cables.
- Aluminum cores are not allowed in low-voltage cables, especially in mining areas where they are strictly prohibited.
**Cable Cross-Section Selection**
The selection of cable cross-section includes both high-voltage and low-voltage cable sizing, with low-voltage cable cross-sections being the primary concern. When selecting the main core size for low-voltage power lines in mining areas—often long and subject to significant current flow—the following four principles should be considered:
1. The cable’s temperature rise during normal operation must not exceed the maximum temperature allowed by its insulation.
2. Voltage loss during operation should be within acceptable limits.
3. The cross-section must meet mechanical strength requirements to ensure durability under harsh conditions.
Mine cables refer to the wiring and cable products used in both surface and underground coal mining equipment. These include cables for coal mining machines, transport systems, communication devices, lighting, signaling, and power supplies for mobile substations, as well as cap lamp wires and drill cables. Proper selection of these cables is essential for maintaining operational safety and efficiency in the mining environment.
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