AC Metal-Enclosed Ring Main Switchgear

The AC metal-enclosed ring main switchgear (referred to as“ring main unit”or“switchgear”) is designed for use in power distribution systems in industrial and mining enterprises, residential communities, high-rise buildings, school campuses, and similar settings. It operates as an indoor AC three-phase 12kV, 50Hz power supply unit for ring networks and terminal power distribution. This equipment is capable of opening and closing rated load currents, transformer no-load currents, and certain lengths of overhead or cable line capacitive currents. Additionally, the load switch-fuse combination unit can interrupt the rated short-circuit current in a single operation. The switchgear provides protection for power distribution systems, enables energy distribution and control, and is equipped with a comprehensive “five-prevention” interlocking mechanism for enhanced safety.

Structural Features

The ring main unit's structure is constructed from partially welded 8MF steel, assembled with bolts for modularity and robustness. It typically incorporates the FZN25-12 two-position vacuum load switch or the FN7-12 gas load break switch. Combined electrical appliances integrate a vacuum load switch with a fuse equipped with a striker. Flexible configuration options allow for the installation of current transformers (CT), potential transformers (PT), or ZnO arresters as needed. For cable entry, the cabinet base includes a removable cover plate for convenient installation, and an optional bus channel can be added for overhead cable entry based on user requirements.

Normal Operating Conditions

1. Temperature:
   • Maximum ambient air temperature: +40°C.
   • Minimum ambient air temperature: -25°C.
   • The average temperature over 24 hours should not exceed +35°C.
2. Altitude:
   • Standard usage: ≤1000m above sea level.
   • Special conditions: ≤2000m above sea level.
3. Atmospheric Conditions:
   • Surrounding air should be free from significant pollution by dust, smoke, corrosive or flammable gases, steam, or salt spray.
4. Humidity:
   • Maximum 24-hour average relative humidity: ≤95%.
   • Maximum 24-hour average water vapor pressure: ≤2.2 kPa.
   • Maximum monthly average relative humidity: ≤90%.
   • Maximum monthly average water vapor pressure: ≤1.8 kPa.
5. Installation:
   • The inclination of the equipment from the vertical plane should not exceed 5°.
   • The equipment must be installed in locations free from severe vibration and mechanical impact.