Ring main unit（RMU）
Future-proof your power grid with our SIS RMU (Solid Insulated Switchgear), the ultimate climate-neutral solution for medium voltage secondary distribution. Unlike traditional GIS RMUs, this innovative unit uses zero greenhouse gases. Instead, all primary live parts—including vacuum interrupters and main busbars—are completely encapsulated in high-dielectric-strength epoxy resin using advanced APG (Automatic Pressure Gelation) technology.
Designedstrictly to meet IEC 62271-200 standards, our SIS RMU completely eliminates the risks of gas leakage, pressure drops, and phase-to-phase internal arcs. It combines the ultra-compact footprint of a gas-insulated unit with the absolute environmental safety of an air-insulated unit, making it the premium choice for eco-conscious projects, extreme climates, and high-altitude installations.
Core Engineering Advantages
• 100% Eco-Friendly (Zero F-Gas): Contains absolutely no SF6 or any other fluorinated gases. It fully complies with the strictest global environmental regulations (such as EU F-gas regulations), eliminating gas monitoring, reporting, and end-of-life recycling costs.
• Immune to Extreme Environments: Because it does not rely on gas pressure, the SIS RMU operates flawlessly in high-altitude regions (where gas pressure drops) and extreme cold environments (where gas can liquefy). Standard operation down to -45°C.
• Single-Phase Encapsulation: Each phase is cast independently in solid epoxy with an external grounded shielding layer. This design physically isolates the phases, effectively reducing the probability of phase-to-phase short circuits to zero.
• Ultra-Compact & Maintenance-Free: Offers a footprint comparable to GIS. The solid encapsulation protects the vacuum arc-extinguishing chamber and conductive parts from dust, moisture, and salt spray, ensuring a completely maintenance-free high-voltage compartment for its 30-year design life.
• Highly Modular Architecture: The solid insulated busbars allow for easy plug-and-play extension on-site. Modules can be swapped, added, or upgraded without any gas handling equipment, significantly reducing downtime.
Technical Specifications
Technical Parameter | Specification (12kV) | Specification (24kV) |
Applicable Standards | IEC 62271-200, IEC 62271-100, IEC 62271-103, IEC 62271-1 | |
Rated Voltage | 12kV | 24kV |
Rated Frequency | 50Hz / 60Hz | 50Hz / 60Hz |
Insulation Medium | Solid Cast Epoxy Resin | Solid Cast Epoxy Resin |
Switching/Arc-Quenching | Vacuum Interrupter | Vacuum Interrupter |
Power Frequency Withstand Voltage (1 min) | Phase to Earth/Phases: 28kV / Across Open Contacts: 32kV | Phase to Earth/Phases: 50kV / Across Open Contacts: 60kV |
Lightning Impulse Withstand Voltage (BIL) | Phase to Earth/Phases: 75kV / Across Open Contacts: 85kV | Phase to Earth/Phases: 125kV / Across Open Contacts: 145kV |
Rated Current (Main Busbar) | 630A / 1250A | 630A / 1250A |
Rated Current (T-off / Feeder) | 630A (LBS) / 630A or 1250A (VCB) | 630A (LBS) / 630A or 1250A (VCB) |
Short-Circuit Breaking Capacity (VCB) | 20kA / 25kA | 20kA / 25kA |
Short-Time Withstand Current (3s) | Up to 25kA | Up to 25kA |
Peak Withstand Current | 62.5kA (at 50Hz) / 65kA (at 60Hz) | 62.5kA (at 50Hz) / 65kA (at 60Hz) |
Internal Arc Classification (IAC) | IAC A-FLR 20kA / 1s or 25kA / 1s | IAC A-FLR 20kA / 1s or 25kA / 1s |
Degree of Protection | HV Compartment: IP67 / Enclosure: IP4X (Standard) | |
Standard Ambient Temperature | -45°C to +45°C | -45°C to +45°C |
Applicable Altitude | Up to 4000m (Standard, can be customized) | Up to 4000m (Standard, can be customized) |
Main Applications
• Eco-Sensitive Zones: National parks, water treatment plants, and urban residential areas enforcing strict zero-emission mandates.
• Extreme Conditions: High-altitude mining sites, offshore wind farms, and regions with severe cold (-45°C) or rapid temperature fluctuations.
• Modern Rail & Infrastructure: Underground transit systems and airport terminals prioritizing fire safety and toxic-gas-free equipment.
• Premium Commercial Assets: Data centers and luxury high-rises where absolute reliability and footprint reduction are critical.
