| Brand | ROCKWILL |
| Series | RMR,RGIS,REC |
An air-insulated ring main unit engineered for primary distribution networks — no SF6, no fluorinated gas, with sealed vacuum interruption. Designed for 12–24kV rings where reliable, clean and low-maintenance protection is required.
A ring main unit insulated by air rather than SF6, built for primary distribution — the part of the network closest to the supply point where reliability matters most.
A primary air insulated RMU uses conditioned air for phase-to-earth and phase-to-phase insulation, paired with a sealed vacuum interrupter for current breaking. Unlike SF6 units, it contains no greenhouse gas, so there is nothing to leak, report or recover. It is sized for 12–24kV primary rings feeding distribution transformers, and type-tested to IEC 62271 for dependable, long-life service.
Conditioned air sealed in the tank provides clean, breathable, non-toxic insulation with zero global warming potential.
Sealed vacuum interrupters handle current breaking independently of the insulation medium, proven over decades.
Type-tested withstand levels for primary distribution, with optional protection and metering for demanding networks.
No fluorinated gas sealed in the tank — zero GWP and no F-gas compliance burden.
Air does not displace oxygen; no asphyxiation risk in cable pits, kiosks or basements.
No gas-density top-ups, just sealed vacuum parts and air-pressure monitoring.
Sealed construction and vacuum interrupters designed for decades of operation.
Steel enclosure and copper busbar recycle as standard materials at end of life.
Built to your ring layout and brand, with IEC 62271 documentation for tenders.
Representative values; the certified datasheet is prepared on request — contact us.
| Parameter | Typical value |
|---|---|
| Rated voltage | 12kV / 24kV |
| Power frequency withstand | 50kV (1 min) |
| Lightning impulse withstand | 125kV |
| Rated frequency | 50 / 60 Hz |
| Insulation medium | Conditioned air — SF6-free, GWP 0 |
| Breaking device | Sealed vacuum interrupter |
| Busbar rated current | 630A (up to 1250A on request) |
| Rated short-time withstand | 20kA / 3s (25kA on request) |
| Configuration | 2 ring incomers + transformer feeder (switch-fuse / VCB) |
| Standard | IEC 62271-1, -102 / -103 |
It is an air-insulated ring main unit built for primary distribution networks — the upstream part of the MV network — using conditioned air and vacuum interruption instead of SF6.
Yes. When dimensioned and type-tested to the IEC 62271 withstand levels, conditioned air provides reliable insulation with sealed vacuum interruption.
Yes. No SF6 or fluorinated gas is sealed in the tank; the global warming potential is zero.
Yes. We manufacture primary air insulated RMUs for distributors and EPCs under OEM/ODM with your nameplate and documentation.
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