Mining-Grade XLPE Insulated Power Cables

Executive Standards
Product design, manufacturing, and testing strictly comply with national coal industry standards and safety specifications:
- Core standard: MT 818.13-2009 (Flame retardant power cables with copper conductors for fixed installation in coal mines at rated voltages up to and including 10 kV – Part 3: XLPE insulated power cables for coal mines).
- Flame retardant standard: Complies with the flame retardant performance test requirements of MT 386 (Flame retardant cables for coal mines).
- Conductor standard: Meets Class 1 (solid) or Class 2 (stranded) conductor requirements of GB/T 3956.

Common Models and Applications
Based on different protective structures, the cables in this series are suitable for various installation environments:
- MYJV: Mining-grade XLPE-insulated, PVC sheathed power cable. For installation indoors, in tunnels, and in ducts; cannot withstand significant mechanical external forces.
- MYJV22: Mining-grade XLPE-insulated, steel tape armored, PVC sheathed power cable. Can withstand certain mechanical pressure; suitable for underground and tunnel installation.
- MYJV32: Mining-grade XLPE-insulated, fine steel wire armored, PVC sheathed power cable. Can withstand substantial mechanical pressure and tensile force; suitable for shaft installation.
- MYJV42: Mining-grade XLPE-insulated, coarse steel wire armored, PVC sheathed power cable. Can withstand extreme mechanical pressure and tensile force.

Product Specification Range
For medium-voltage power systems (6 kV and above), the cables generally adopt a three-core configuration with a broad cross-section range:
- Rated voltage grades: 3.6/6 kV, 6/6 kV, 6/10 kV, 8.7/10 kV.
- Nominal conductor cross-sections:
  - MYJV, MYJV22, MYJV32 types: 3×25 mm² – 3×300 mm².
  - MYJV42 type: 3×50 mm² – 3×300 mm².

Core Technical Parameters
1. Rated voltage (U₀/U): Up to 8.7/10 kV (corresponding to maximum system voltage Um = 12 kV).
2. Temperature characteristics:
   - Maximum continuous permissible conductor operating temperature: 90°C.
   - Maximum conductor temperature during short circuit (max. 5 s): 250°C.
   - Installation ambient temperature: Not lower than 0°C (preheating required below 0°C).
3. Electrical performance: Insulation resistance constant at maximum rated temperature Ki ≥ 3.67 MΩ·km.
4. Bending radius: Minimum bending radius not less than 15 times the cable outer diameter.

Cable Structural Characteristics
- High-purity conductor: Made of high-purity oxygen-free round copper wire, ensuring very low DC resistance and high conductivity.
- Advanced insulation layer: XLPE insulation offers strong electrical insulation properties and thermal stability.
- Shielding structure: For voltage grades at 3.6/6 kV and above, both conductor and insulation are provided with semiconductive shielding and metallic shielding (copper tape) to ensure a uniform electric field and suppress partial discharge.
- Heavy-duty mechanical protection (armored types): Steel tape or steel wire armor provides extremely high compressive and tensile strength, resisting external forces such as mine car impact and rock squeezing.
- Mining-grade flame retardant sheath: The outer sheath is made of a specialized flame retardant PVC compound, featuring resistance to abrasion, oil, and acid/alkali corrosion.

Applicable Scenarios
- Fixed mine power supply: Main power supply lines from central substations to district substations.
- Shafts and vertical pits: MYJV32/42 type cables, with their high tensile strength, are specifically designed for vertical installations such as mine shafts with high head drops.
- Fully mechanized mining face support: Provides stable medium-voltage power to underground mobile substations or large fixed mining equipment.

Safety Certification and Approval Recommendations
- MA coal mine safety certification: As a safety-critical product for mining, this cable must obtain the Mining Product Safety Approval Certificate (MA mark) before being used underground in coal mines.
- Flame retardant classification: Products with conductor cross-sections ≥ 50 mm² typically meet Category A bunched burning requirements; those < 50 mm² meet Category B bunched burning requirements.
- Selection note: During selection, carefully verify the voltage rating to ensure that the U₀ value matches the earth fault operating conditions of the power system (Category A or B system).