Mobile Rubber Sheathed Flexible Cable for Coal Mines (MY/MYP/MYPTJ Series)

Executive Standards
This product series strictly complies with national coal industry standards and relevant enterprise technical specifications:
- National industry standards: MT/T 818.5-2009, MT/T 818.6-2009, MT/T 818.7-2009, MT/T 818.9-2009.
- Core enterprise standards: Q/320481SS139.5-2020, Q/320481SS139.6-2020, Q/320481SS139.7-2020.

Model Code Definitions
The model code defines the application grade and protective construction of the cable through letter combinations:
- M: Series code, denoting coal mine use.
- Y: Function code, denoting mobile.
- P: Protection code, denoting non-metallic shielding (generally semi-conductive rubber shielding).
- PT: Protection code, denoting metallic shielding.
- J: Function code, denoting the presence of a monitoring core.
- Q: Grade code, denoting light-duty.

Product Specifications and Voltage Ratings
This series provides a complete range of mobile cables for coal mines to meet different load requirements:
1. Low voltage power cable (MY / MYP):
   - Rated voltage: 0.38/0.66 kV, 0.66/1.14 kV.
   - Specifications: Single-core (1×4 – 1×400 mm²); multi-core power (3×4+1×4 – 3×150+1×50 mm²); large cross-section shielded type (3×185+1×50 mm²).
2. High voltage shielded monitoring type cable (MYPTJ):
   - Rated voltage: 3.6/6 kV, 6/10 kV, 8.7/10 kV.
   - Specifications: 3×25+3×16/3+3×2.5 – 3×185+3×50/3+3×2.5.
3. High voltage metallic shielded cable (MYPT):
   - Rated voltage: 1.9/3.3 kV to 8.7/10 kV.
   - Specifications: 3×16+3×16/3 – 3×185+3×50/3.
4. Light-duty mobile flexible cable (MYQ):
   - Rated voltage: 0.3/0.5 kV.
   - Specifications: 2-core to 12-core, cross-section 1.0 – 2.5 mm².

Core Technical Parameters
1. Operating temperature: The maximum continuous permissible conductor operating temperature is generally 65 °C or 90 °C (depending on the insulation material).
2. Electrical performance: Features very high insulation resistance and stable dielectric strength. 10 kV grade products must undergo a stringent power-frequency voltage withstand test before delivery.
3. Flame retardant performance: The finished cable must pass the flame retardant test specified in MT 386 to ensure that flames do not propagate in the event of a fault fire underground.
4. Flexing performance: The cable has a very small bending radius (generally not less than 6–15 times the overall cable diameter), capable of adapting to frequent coiling and dragging.

Cable Structural Characteristics
- Specialty conductor: Made of high-purity annealed flexible copper wires precision-stranded to ensure the cable does not suffer fatigue fracture after tens of thousands of flexing cycles.
- Dual shielding construction:
  - Semi-conductive shielding: Used to balance the electric field and reduce partial discharge in the insulation layer.
  - Metallic shielding: Adopts copper wire braiding or wrapping, providing both electromagnetic shielding and short-circuit fault current carrying capacity.
- Monitoring core system: Types such as MYPTJ have a built-in monitoring core that can detect the integrity of the cable earthing system in real time. In the event of an open circuit or leakage, the monitoring system can immediately cut off the power supply.
- Heavy-duty sheath: The outer sheath is made of high-performance chlorinated polyethylene (CPE) or similar rubber, offering outstanding impact resistance, corrosion resistance, and moisture penetration resistance.

Applicable Scenarios
- Underground mobile equipment: Used to connect various mobile substations, distribution boxes, conveyors, water pumps, etc.
- Handheld tools: MYQ type cable is suitable for electric drills, lighting fixtures, and small automated machinery.
- Heading face: Provides safe and reliable power supply for mobile machinery in complex heading environments.