| Brand | ROCKWILL |
| Series | RMR，REC |
As a leading SF6-free RMU manufacturer and dry air switchgear manufacturer, we deliver eco-friendly medium voltage switchgear. Our SF6-free RMU serves as the ideal SF6 replacement switchgear and SF6 alternative RMU — a 12–24kV zero GWP RMU and zero GWP switchgear, with a 24kV SF6 free RMU variant available. This pure air insulated RMU / dry air RMU replaces SF6 with dry compressed air or solid insulation, offering the same 12–24kV protection and switching performance, zero greenhouse-gas impact, and full IEC 62271 compliance.
A ring main unit (RMU) is the compact, metal-enclosed switchgear installed at the secondary substations that feed cities, industrial parks and commercial buildings. A conventional RMU insulates and interrupts current using sulfur hexafluoride (SF6) — a powerful greenhouse gas. An SF6-free RMU delivers the same ring-network and transformer-protection function without any SF6, using dry air or solid dielectric instead.
The tank is filled with clean, dry compressed air that provides phase-to-earth and phase-to-phase insulation. Harmless if leaked, fully recyclable at end of life.
Busbar and switching parts encapsulated in epoxy/resin solid insulation for the most compact footprint and polluted or humid environments.
Current breaking is handled by sealed vacuum interrupters — proven, silent and maintenance-light, independent of the insulation gas.
The design separates the two jobs that SF6 traditionally did at once — insulation and arc interruption — and assigns each to the best SF6-free technology.
Two ring-feed incomers and one or more transformer feeders connect to the earthed, metal-enclosed tank.
Dry compressed air (or solid epoxy) holds off the 12–24kV voltage between live parts and earth — zero GWP.
Load-break switches make/break load current; on transformer feeders, a switch-fuse combination or vacuum CB clears fault current fast.
Optional pressure sensor, position indicators and SCADA interface feed data to the distribution automation system.
SF6 is being phased out across distribution equipment. Going SF6-free now avoids retrofits, re-engineering and stranded assets later.
No leaked fluorinated gas means no CO2-equivalent emissions to report and offset — a direct win for net-zero targets.
Air does not displace oxygen like heavy SF6. No special gas-handling, recovery or asphyxiation precautions for installers.
No periodic gas-density checks, top-ups or end-of-life gas recovery. Sealed vacuum parts are designed for decades of service.
Dimensions, cable entry and operation match conventional RMUs, so contractors need no new skills or tooling.
Add condition monitoring and remote control to turn the RMU into an intelligent node of the distribution network.
Representative values of our dry-air / solid-insulated range. The certified datasheet for your project is prepared on request — contact us.
| Parameter | Dry-air type | Solid-insulated type |
|---|---|---|
| Rated voltage | 12kV / 24kV | 12kV / 24kV (up to 36kV) |
| Rated frequency | 50 / 60 Hz | 50 / 60 Hz |
| Insulation medium | Dry compressed air (SF6-free) | Epoxy/resin solid insulation |
| Arc interruption | Sealed vacuum interrupter | Sealed vacuum interrupter |
| Busbar rated current | 630A | 630A (up to 1250A on request) |
| Transformer feeder | Switch-fuse combination / VCB | Switch-fuse combination / VCB |
| Rated short-time withstand | 20kA / 3s | 20kA / 3s (25kA on request) |
| Standard | IEC 62271-1 / -102 / -103 | IEC 62271-1 / -200 |
| Degree of protection | Up to IP4X / IP5X | Up to IP4X / IP5X |
| Global warming potential | Zero | Zero |
| SF6-free RMU | Conventional SF6 RMU | |
|---|---|---|
| Climate impact | Zero GWP | SF6 GWP ≈ 23,500 |
| Regulatory risk | Future-proof | Increasing restrictions & reporting |
| Interruption technology | Vacuum | SF6 or vacuum (hybrid) |
| Site safety on leak | Harmless air / solid | Asphyxiation risk, recovery needed |
| Maintenance | Pressure monitor, sealed vacuum | Gas-density checks & top-ups |
| End of life | Standard recycling | Specialized gas recovery & disposal |
Ring-feed incomers in urban and suburban medium-voltage networks.
Transformer protection for factories, data centers, shopping malls and high-rises.
Grid connection for solar PV and wind farms where green credentials matter.
Send us your single-line diagram, voltage and fault-level requirements. We will reply with a configuration, certified datasheet and export quote within one working day.
Yes. The interruption function uses sealed vacuum interrupters — the same proven technology used across millions of feeders — while dry air or solid insulation handles the steady-state insulation. Ratings and fault performance meet the same IEC 62271 class.
Two technologies: dry compressed air insulation for the greenest, most recyclable solution, and solid epoxy/resin insulation for the most compact footprint and harsh environments. We can specify the best fit for your site conditions.
Standard 12kV and 24kV class units; 36kV solid-insulated units are available on request. Send your rated current and fault level for an exact configuration.
Yes. We manufacture under OEM/ODM arrangements for switchgear distributors, EPC contractors and brands, including your own nameplate, custom layouts and documentation.
Type-test reports to IEC 62271-1 and the relevant product standards, CE documentation and factory acceptance support are supplied with each shipment.
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