Dis Sub-12 SF6-Free Gas-Insulated RMU (12kV)
RAYDAFON Dis Sub-12 SF6-Free Gas-Insulated RMU delivers 12kV distribution switching with zero SF6 emissions — using dry air and eco-friendly mixed gas sealed in an IP67 stainless steel tank. Rated 630A (1250A optional) with 20kA short-circuit withstand. Modular design supports up to 5 modules per tank with busbar extension. Vacuum interrupter and three-station isolating switch ensure safe, maintenance-free operation for 30 years. Ideal for utility distribution networks, industrial parks, and renewable substations.
What Is an SF6-Free Gas-Insulated RMU?
An SF6-free gas-insulated RMU (Ring Main Unit) is a medium-voltage switchgear that uses dry air and eco-friendly mixed gas instead of SF6 (sulfur hexafluoride) for insulation. SF6 is a potent greenhouse gas with a global warming potential (GWP) of 23,500 — 23,500 times that of CO2 — and is regulated under the Kyoto Protocol and EU F-Gas Regulation. The RAYDAFON Dis Sub-12 replaces it with safe, environmentally friendly gas sealed in an IP67 stainless steel tank, delivering the dielectric strength required for 12kV distribution networks while eliminating gas leakage risk, regulatory exposure, and future retrofit cost. Every core component — vacuum circuit breaker, load switch, three-station isolating switch, and insulated bushings — is sealed inside the gas tank for 30-year maintenance-free operation.
12kV Rated Voltage Zero SF6 Emissions IP67 Sealed Gas Tank 30-Year Maintenance-Free
SF6 vs. Eco-Friendly Gas: Why the Switch Matters
23,500GWP
SF6 Gas
GWP of 23,500 CO₂-equivalent. Regulated under Kyoto Protocol and EU F-Gas Regulation. Requires leakage monitoring, reclamation at end-of-life, and eventual retrofit.
≈1GWP
Dry Air / Eco-Gas
GWP approximately 1 (equivalent to CO₂). No leakage regulatory burden. No end-of-life reclamation cost. Compliant with current and future environmental regulations.
Inside the Sealed Gas Tank
The core architecture of the Dis Sub-12 is a fully sealed stainless steel gas tank that houses four critical switching components in a maintenance-free environment. All live parts operate inside the tank — no exposure to dust, humidity, or contamination.
Sealed Gas Tank — Internal Architecture
VCB
Vacuum Circuit Breaker Main Switching
GAS
Dry Air + Eco-Gas Insulation
3ST
Three-Station Switch Isolate / Ground
BSH
Insulated Bushings Cable Interface
Vacuum interrupter and vacuum load switch adopt a general main structure design for consistent switch body behavior. The three-station isolating/grounding switch uses a mature knife-gate structure that prevents the risk of live contact in the main circuit. Spring mechanism is simple and reliable with knob operation.
Three Switch Configurations for Different Circuits
VACUUM CIRCUIT BREAKER
Main Incoming / High-Load Feeder
Vacuum interrupter provides the highest breaking capacity and longest electrical life. Suitable for transformer protection, main incoming circuits, and feeders with frequent switching duty.
Rated current630A / 1250A
Breaking current20kA / 25kA
Mechanical lifeM2 · 10,000 ops
LOAD SWITCH
Standard Feeder / Ring Circuit
Load-break switch for normal load switching in ring main and radial distribution circuits. Compact, reliable, and cost-effective for typical feeder configurations.
Rated current630A
Short-time withstand20kA / 4s
Mechanical lifeM2 · 10,000 ops
LOAD SWITCH + FUSE
Transformer Protection Feeder
Combined load switch with high-voltage fuse for transformer protection. Simple, economical, and self-powered protection without external relay.
Rated current200A
Breaking current31.5kA
Switching current3,150A
Modular Design — Up to 5 Modules Per Tank
One sealed gas tank can contain up to five modules. Additional modules are added through busbar extension for larger substations. This modular architecture allows customization for different incoming and feeder line requirements without redesigning the RMU.
I
Incoming
Cable or busbar incoming
O1
Outgoing
Feeder to load or transformer
BT
Bus-Tie
Busbar sectionalizing
M
Metering
CT / PT chamber
+
EXT
Extension
Busbar expansion
Technical Specifications
GENERAL
Rated voltage12 kV
Rated frequency50 Hz (60 Hz opt.)
Power freq. withstand42 / 48 kV/min
Lightning impulse75 / 85 kV
Arc duration≥ 0.5 s
Operating voltageDC 24-220V / AC 110-220V
BUS SYSTEM
Rated current630 A (1250 A opt.)
Short-time withstand20 / 4 kA/s (25/4 opt.)
Peak withstand50 kA (63 kA opt.)
Protection (primary)IP67 sealed tank
Protection (cubicle)IP4X
Protection (compartment)IP2X
LOAD SWITCH
Rated current630 A
Closing current50 kA
Short-time withstand20 kA / 4 s
Mech. life (load sw)M2 · 10,000 ops
Mech. life (3-station)M1 · 3,000 ops
Electrical lifeE2 · 100 ops
CIRCUIT BREAKER
Rated current630 A (1250 A opt.)
Breaking current20 kA (25 kA opt.)
Closing current50 kA (63 kA opt.)
Mech. lifeM2 · 10,000 ops
Electrical lifeE2
Duty cycleO-0.3s-CO-180s-CO
Product Features
- Maintenance-free 30 years — Dry air, movable and fixed contacts, arc-extinguishing chamber, and busbar are sealed in one gas box. No periodic gas monitoring or topping-up required.
- Full-sealed, insulated in-out cables — Full-sealed insulated cable connectors matched to user requirements. Electrified display shows each circuit status precisely.
- Modularized and expansible — Combination of expansible modules. One gas tank holds up to 5 modules; additional modules connect through busbar extension.
- Multiple connection schemes — Load switch, load switch + fuse, or vacuum circuit breaker combinations for various incoming and feeder line circuits.
- Visible open contacts — Observation window on the panel shows the open contacts of the load switch and the position of the grounding switch.
- Electric operation and FTU-ready — Special voltage transformers collect power for operating mechanism and FTU. Special battery and charging modules ensure continuous power supply.
- Eco-friendly SF6-free insulation — Dry air and eco-friendly mixed gas eliminate greenhouse gas emissions and future regulatory risk.
- Full remote monitoring integration — Compatible with RAYDAFON Remote-9001 monitoring unit for complete smart substation deployment. See remote monitoring →
Industry Applications
The SF6-free RMU is designed for distribution networks where environmental compliance, reliability, and long service life are all critical. The modular design adapts to a wide range of substation configurations.
- Utility Distribution Networks — Primary and secondary distribution switching for urban and suburban grid networks. The SF6-free design meets current and future environmental regulations.
- Industrial Parks & Manufacturing Plants — Compact RMU installation for medium-voltage distribution within factories, industrial zones, and logistics centers. See prefabricated substations →
- Commercial Buildings & Data Centers — Ring main units for reliable power supply in office towers, shopping malls, hospitals, and data center campuses.
- Renewable Energy Substations — Wind and solar farm collector substations requiring 12kV medium-voltage switchgear that aligns with the renewable industry's clean-energy commitments. See ESS range →
- Rail & Metro Substations — Traction and station power distribution networks with SF6-free medium-voltage switchgear.
- Oil & Gas Facilities — Onshore and offshore substations where SF6 monitoring and reclamation is costly or impractical.
- Telecom & Remote Sites — Unmanned remote substations with 30-year maintenance-free operation eliminating periodic site visits.
- Prefabricated Substation Integration — Designed to fit directly into RAYDAFON YBM prefabricated substations for rapid site installation. See RMU range →
Why Choose RAYDAFON as Your SF6-Free RMU Manufacturer
- 20+ Years of Power Equipment Experience — RAYDAFON Technology Group has served the electrical equipment industry for over two decades, with products deployed across 40+ export countries.
- Integrated Switchgear & Substation Manufacturing — We manufacture RMUs, switchgear, prefabricated substations, and monitoring units under one roof. The Dis Sub-12 integrates seamlessly with our YBM prefabricated substations for a complete turnkey distribution solution.
- 25+ Patents — Proprietary designs across gas tank sealing, vacuum interrupter mounting, three-station switch knife-gate geometry, and modular expansion architecture.
- ISO/IEC Certified Manufacturing — All products manufactured under ISO/IEC quality management systems and tested to IEC 62271-200 standards, with full third-party type-test reports available on request.
- OEM/ODM Support — Custom voltage ratings, protection schemes, communication protocols, and FTU integration to match your project specification.
- 24-Hour Engineering Response — Dedicated engineering team provides technical selection support and after-sales service within 24 hours.
Frequently Asked Questions
What is an SF6-free gas-insulated RMU?
An SF6-free gas-insulated RMU (Ring Main Unit) is a medium-voltage switchgear that uses dry air or an eco-friendly mixed gas instead of SF6 (sulfur hexafluoride) for insulation. SF6 is a potent greenhouse gas with a GWP of 23,500 — roughly 23,500 times that of CO2. The RAYDAFON Dis Sub-12 uses safe, environmentally friendly mixed gas sealed in a stainless steel tank, eliminating gas leakage risk and pollution while maintaining the high dielectric strength required for 12kV distribution networks.
Why choose SF6-free over traditional SF6 RMU?
SF6 is regulated under the EU F-Gas Regulation and the Kyoto Protocol due to its extremely high global warming potential. Many countries now require SF6-free alternatives for new distribution projects. The SF6-free RMU avoids future regulatory risk, eliminates the cost of SF6 gas monitoring and reclamation, removes leakage hazard, and delivers equal or better dielectric performance through advanced dry air / eco-gas insulation and vacuum interrupter technology.
What are the technical specifications of the Dis Sub-12 RMU?
The Dis Sub-12 is rated 12kV, 50Hz (60Hz optional), with 630A rated current (1250A optional) and 20kA/4s short-time withstand current (25kA/4s optional). Peak withstand current is 50kA (63kA optional). The sealed gas tank is IP67-rated, the cubicle is IP4X, and the compartment is IP2X. Maintenance-free life is 30 years. Operating power supply supports DC 24/48/110/220V and AC 110/220V.
How many modules can be combined in one RMU?
One sealed gas tank can contain up to 5 modules, covering incoming, outgoing, bus-tie, and metering configurations. Additional modules can be added through busbar extension for larger substations. Load switch, load switch + fuse, and vacuum circuit breaker combinations are available for different incoming and feeder line requirements.
What is the delivery time and MOQ for the Dis Sub-12 RMU?
Standard configurations ship within 30-60 days from order confirmation. MOQ is 1 unit. Custom voltage ratings, communication protocols, or integrated FTU configurations may require 60-90 days. We accept sample orders for validation testing.
Can it be integrated into a prefabricated substation?
Yes. The Dis Sub-12 is designed to fit directly into RAYDAFON YBM prefabricated substations (12kV/24kV/40.5kV). For turnkey distribution projects, both the RMU and the substation can be supplied from one source. See prefabricated substations →
Related Equipment
For a complete SF6-free distribution solution, pair the Dis Sub-12 with:
- SF6-Free Gas-Insulated RMU Range — Full family of SF6-free RMUs for 12kV, 24kV, and 40.5kV systems
- YBM Prefabricated Substations — Containerized substations with factory-integrated RMU
- Remote-9001 Monitoring Unit — For smart monitoring and SCADA integration
- Medium Voltage Switchgear — For primary distribution switchgear applications
12kV rated voltage, 630A / 1250A current
IP67 sealed stainless steel gas tank
Zero SF6 emissions — GWP ≈ 1
30-year maintenance-free life
Up to 5 modules per tank, busbar expansion
IEC 62271-200 type-tested
Ready to Specify Your SF6-Free RMU?
Share your voltage rating, current rating, and module configuration — our engineers will reply with a tailored Dis Sub-12 configuration and factory-direct quote within 24 hours.
Request Quote NowCompare SF6 vs SF6-Free RMU →
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