Ring main unit（RMU）
Designed for the most demanding secondary distribution networks, our Gas Insulated Ring Main Unit (GIS RMU) is a fully sealed, compact, and climate-independent switchgear. All primary live parts—including the busbars, load break switches, and circuit breakers—are completely enclosed in a robotically laser-welded stainless steel tank filled with SF6 gas (or eco-friendly gas alternatives) as the insulation and arc-quenching medium.
Strictly type-tested to IEC 62271-200, this GIS RMU guarantees zero exposure to environmental elements like high humidity, dust, salt spray, or flooding. It provides a fit-and-forget solution with a 30-year design life, making it the industry standard for modern urban grids, renewable energy plants, and heavy industrial applications.
Core Engineering Advantages
• Hermetically Sealed & Climate-Independent: The primary gas tank boasts an IP67 protection rating. It is completely immune to external environmental conditions, ensuring stable operation in coastal areas, deserts, or underground substations subject to high moisture.
• Compact Footprint: By utilizing gas insulation, the clearance between live phases is drastically reduced. This results in a switchgear footprint up to 50% smaller than traditional Air Insulated Switchgear (AIS), saving highly valuable real estate in city centers and wind turbine towers.
• Zero Routine Maintenance: The sealed gas tank requires zero maintenance on the high-voltage components over its entire lifespan. This translates to significantly lower Operational Expenditure (OPEX) and eliminates the need for frequent site visits.
• Maximum Operator Safety: Features a built-in mechanical interlocking system and a dedicated pressure relief valve. In the rare event of an internal fault, the arc gases are directed downwards or backwards into the cable trench, fully complying with IAC AFL / AFLR safety standards.
• Flexible Configurations (Compact or Extensible): Available in standard non-extensible blocks (e.g., CCV, CCC, CCF) for simple ring networks, or as fully extensible modules that can be joined via shielded solid insulated busbars for future grid expansion.
• Smart Grid Ready: Pre-engineered to house motorized mechanisms, protection relays (self-powered or auxiliary), and Remote Terminal Units (RTU) for SCADA monitoring, enabling rapid fault isolation and power restoration.
Technical Specifications
Applicable Standards | IEC 62271-200, IEC 62271-100, IEC 62271-103 |
Rated Voltage | 12kV / 17.5kV / 24kV |
Rated Frequency | 50Hz / 60Hz |
Insulation Medium | SF6 Gas / Eco-Gas Alternatives |
Rated Current (Busbar) | 630A / 1250A |
Rated Current (LBS / VCB) | 630A (LBS) / 630A or 1250A (VCB) |
Short-Circuit Breaking Capacity | 21kA / 25kA |
Short-Time Withstand Current | Up to 25kA for 3s |
Internal Arc Classification (IAC) | IAC A-FL / IAC A-FLR 21kA/1s |
Degree of Protection | Gas Tank: IP67 / Enclosure: IP3X to IP4X |
Gas Leakage Rate | < 0.1% per year |
Main Applications
• Renewable Energy Integration: Inside wind turbine towers and solar PV collector networks due to its compact size and high reliability.
• Urban Underground Networks: Basement substations and compact utility kiosks in densely populated cities.
• Harsh Environments: Coastal facilities, mining sites, and railway power distribution.
• Commercial Complexes: Hospitals, airports, and large shopping malls requiring uninterrupted power supply.
