As global carbon neutrality accelerates and the power industry imposes stricter controls on greenhouse gases, traditional SF₆‑based ring main units (RMUs) are facing unprecedented challenges. In response, Eco‑friendly Gas Insulated Ring Main Units using dry air, nitrogen, or novel alternative gases have emerged as the most promising technological upgrade for medium voltage switchgear.
SF₆ gas has excellent insulation and arc‑quenching properties, but its Global Warming Potential (GWP) is approximately 23,500 times that of CO₂, with an atmospheric lifetime of 3,200 years. As one of the major SF₆ users, the power industry is actively seeking alternatives. Eco‑friendly gas insulated RMUs are developed exactly for this need, featuring:
- Ultra‑low GWP – Using dry air, N₂ or C₅‑FK mixtures with GWP close to zero, completely SF₆‑free.
- Regulatory compliance – Meeting the EU F‑Gas regulation and global policies phasing down SF₆.
- Reliable performance – Through optimized electric field design and gas‑chamber structure, achieving insulation levels and operational life comparable to conventional SF₆ RMUs.
Mainstream eco‑friendly gas insulated RMUs fall into two categories:
Clean, dry air or industrial nitrogen is used as the primary insulation medium. Insulation strength is ensured by moderately increasing gas pressure (e.g. 0.02–0.04 MPa gauge) and shaping electrodes optimally. This route offers mature technology, extremely low gas cost, and zero environmental risk, suitable for 12kV–24kV voltage levels.
Blends of gases such as C₄F₇N or C₅‑FK with CO₂ or dry air are used. These gases combine low GWP (C₄F₇N has GWP about 1/20 that of SF₆) with relatively high dielectric strength, achieving SF₆‑like insulation performance at near‑atmospheric pressure – ideal where compact dimensions are required.
Eco‑friendly RMUs typically adopt a vacuum interrupter for breaking duties, while the eco‑friendly gas serves only as the insulating medium for disconnectors and earthing switches – elegantly bypassing the difficulty of gas‑based arc quenching. Vacuum interrupters provide strong breaking capacity, long electrical life, and maintenance‑free operation, perfectly complementing eco‑friendly gas insulation.
A fully sealed stainless steel tank (laser‑welded) with strict helium leak testing ensures an extremely low annual leakage rate (typically <0.1%). A gas pressure gauge or density monitor provides real‑time pressure indication, guaranteeing insulation reliability throughout the equipment’s lifecycle.
Combined with spring operating mechanisms (such as your GHCT‑01 DC motor‑charged mechanism) or magnetic actuators, the RMU supports electric, manual, and remote control, fully meeting distribution automation interface requirements.
Eco‑friendly gas insulated RMUs have been widely used in domestic and international distribution projects, including:
- Renewable energy plants – PV, wind power skid‑mounted substations and step‑up substations.
- Urban distribution networks – Commercial & residential areas, schools, hospitals, and other environmentally sensitive locations.
- Industrial & mining facilities – Parks and projects with strict environmental requirements.
- Overseas projects – International EPC power contracts requiring EU F‑Gas compliance.
At present, 12kV eco‑friendly gas insulated RMUs are mature, with many local manufacturers having obtained type test reports and put units into grid operation. For both manufacturers and end users, early adoption of eco‑friendly RMUs helps to:
- Stay ahead of stricter SF₆ control policies.
- Improve corporate green manufacturing and ESG ratings.
- Seize emerging market opportunities in domestic and international power distribution.
Jiangsu Changyun Intelligent Technology Co., Ltd. closely follows the development of eco‑friendly gas insulated RMU technology. Combining our GHCT series DC spring operating mechanisms, we offer SF₆‑free, high‑reliability, and intelligent medium‑voltage switchgear solutions for our customers.
If you are interested in this product direction, please contact us for more technical and cooperation information.
