Conveyor Belt Power: Specifying Type 7S 3.3kV 3x70mm² for Underground Coal Conveyors
Type 7S is a single-core, flexible mining machine cable designed for direct connection to motor terminals and equipment in high-vibration underground environments. When a specification calls for “Type 7S 3.3kV 3x70mm²,” it refers to three separate, individual single-core cables (each one being 1x70mm² in cross-section), which are installed in trefoil formation (arranged in a triangular pattern) to create a complete three-phase power system for a conveyor drive motor. Each single core has its own 360-degree copper screening layer, Class 5 extra-flexible stranded conductors, and a signature glass fiber braid reinforcement layer that provides superior vibration and thermal resistance. This combination makes Type 7S the preferred cable choice for main conveyor systems in underground coal mines, where the motor is subject to continuous high-frequency vibration, the terminal space is confined, and flexibility is essential for reliable long-term operation.
