Dis Sub-12 Compact Air-Insulated RMU (12kV)
RAYDAFON Dis Sub-12 Compact Air-Insulated RMU delivers 12kV distribution in a 500mm-wide cabinet — the most compact fixed air-insulated switchgear for box substations and ring networks. Uses air insulation with no gas filling and no harmful emissions. Integrated three-station isolating switch + fixed vacuum circuit breaker, pressure relief channels on top and rear, and modular C/F/V/PT/M/D configurations. Rated 1250A, 31.5kA/4s withstand, IP4X enclosure.
What Is an Air-Insulated RMU?
An air-insulated RMU (Ring Main Unit) is a medium-voltage switchgear that uses air as the primary insulation medium instead of SF6 gas or eco-gas mixtures. The RAYDAFON Dis Sub-12 places the busbar and insulated conductors in air rather than in a sealed gas tank — making it maintenance-friendly, fully recyclable at end-of-life, and free from gas leakage risk. It achieves 12kV dielectric strength through epoxy-insulated conductors and an optimized three-phase vertical layout, achieving a cabinet width of only 500mm — the most compact fixed air-insulated design available for box-type substations and ring network distribution systems.
Air-Insulated · No Gas 500mm Cabinet Width 12kV / 1250A / 31.5kA Modular C/F/V/PT/M/D
500mm Cabinet Width — Why Compactness Matters
Cabinet Width Comparison
The three-phase vertical layout stacks the three phase conductors vertically rather than side by side — a design that reduces cabinet width by up to 50% compared to conventional horizontal-layout switchgear. In a box-type substation or a containerized distribution room, this translates directly into more feeders per square meter and lower civil construction cost.
Four Design Principles
01
Safety Through Structure
The vacuum interrupter structure is solid, with pressure relief channels both above and behind the cabinet. These channels direct arc products away from the operator zone in the event of internal arc fault, reducing the risk of internal combustion and ensuring the safety of personnel and property. The enclosure is maintainable throughout its service life.
02
Environmental Protection
No gas filling, no harmful gas emissions. The air-insulated design eliminates SF6 — a greenhouse gas with GWP 23,500 — and any eco-gas mixture. At end-of-life, all primary components can be separated and recycled without gas reclamation procedures.
03
Miniaturization, Modularity, Intelligence
Cabinet width is only 500mm, occupying less site area. Inlet and outlet cable installation height is ≥600mm. All conductors use hard connection for easy maintenance. Any combination of protection, control, and monitoring functions is fully integrated to meet distribution network automation requirements.
04
Flexible Configuration
Six standard module types (C circuit breaker, F load switch + fuse, V vacuum circuit breaker, PT voltage transformer, M metering, D bus-tie) can be combined in any arrangement. Both above-ground and below-ground isolation are supported. See full RMU range →
Six Configurable Module Types
C Circuit Breaker Cable feeder protection
F Load Switch + Fuse Transformer protection
V Vacuum CB High-load switching
PT Voltage Transformer Protection voltage
M Metering CT / PT chamber
D Bus-Tie Busbar sectionalizing
Key Ratings at a Glance
12kV Rated Voltage
1250A Rated Current
31.5kA Short-Time Withstand
500mm Cabinet Width
Full Technical Parameter Table
| Item | Unit | Parameter |
|---|---|---|
| Rated Voltage (Ur) | kV | 12 |
| Rated Frequency (fr) | Hz | 50 |
| Rated Current (Ir) — Main | A | 1250 |
| Rated Current (Ir) — Fuse Circuit | A | 125* |
| Power Freq. Withstand — Phase-Earth | kV | 42 |
| Power Freq. Withstand — Isolated Fracture | kV | 48 |
| Lightning Impulse — Phase-Earth | kV | 75 |
| Lightning Impulse — Isolated Fracture | kV | 85 |
| Power Freq. Withstand — Auxiliary Circuit | kV | 2 |
| Short-Time Withstand — Main / Ground (4s) | kA | 31.5 |
| Short-Time Withstand — Earth Circuit (2s) | kA | 27.4 |
| Peak Withstand — Main / Ground | kA | 80 |
| Peak Withstand — Earth Circuit | kA | 68.5 |
| Short-Circuit Closing Current | kA | 80 (V) / 63 (C) |
| Short-Circuit Breaking Current | kA | 31.5 |
| Rated Transfer Current | A | 3150 |
| Operation Sequence | — | O-0.3s-CO-180s-CO |
| Short-Circuit Breaking Times | times | 30 |
| Mechanical Life — CB / Load Switch | ops | 10,000 |
| Mechanical Life — Three-Station Switch | ops | 5,000 |
| Enclosure Protection Grade | — | IP4X |
* Rated current of load switch + fuse combination depends on the high-voltage fuse selected. Rated short-circuit breaking current is limited by the high-voltage fuse.
Industry Applications
- Box-Type Substations — The 500mm cabinet width makes this RMU the preferred switchgear for compact box-type (pad-mounted) substations in residential communities, commercial complexes, and industrial parks.
- Ring Network Distribution — Ideal for ring main distribution networks where multiple RMU units are interconnected in a loop configuration for high-reliability power supply.
- Industrial Parks & Manufacturing Plants — Medium-voltage distribution inside factories, logistics centers, and industrial zones. See prefabricated substations →
- Commercial Buildings & Data Centers — Reliable medium-voltage switching for office towers, shopping malls, hospitals, and data center campuses.
- Renewable Energy Collector Substations — Wind and solar farm collector systems requiring air-insulated RMUs with zero gas handling. See ESS range →
- Rail & Metro Stations — Auxiliary power distribution networks in metro stations and light-rail systems.
- Airport & Port Facilities — Distribution networks for apron lighting, hangar power, and terminal buildings.
- Smart Grid Integration — Fully compatible with RAYDAFON Remote-9001 monitoring for remote operation and SCADA integration. See remote monitoring →
Why Choose RAYDAFON as Your Air-Insulated 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 directly with our YBM prefabricated substations for turnkey distribution projects.
- 25+ Patents — Proprietary designs across three-phase vertical layout, pressure relief channel geometry, three-station switch mechanism, 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 air-insulated RMU?
An air-insulated RMU (Ring Main Unit) is a medium-voltage switchgear that uses air as the primary insulation medium instead of SF6 gas or eco-gas mixtures. The Dis Sub-12 air-insulated RMU places the busbar and insulated conductors in air rather than in a sealed gas tank, making it maintenance-friendly, recyclable at end-of-life, and free from gas leakage risk — while still achieving 12kV dielectric strength through epoxy-insulated conductors and optimized phase spacing.
What is the cabinet width of the Dis Sub-12?
The Dis Sub-12 Compact Air-Insulated RMU has a cabinet width of only 500 mm per module. This is achieved through a three-phase vertical layout that stacks the three phase conductors vertically rather than horizontally. The compact width lets more units fit into a substation footprint or a prefabricated substation, and the cable installation height is ≥600 mm for easy cable termination.
What modular configurations are available?
The Dis Sub-12 supports six configurable module types: C (circuit breaker feeder), F (load switch + fuse, for transformer protection), V (vacuum circuit breaker), PT (voltage transformer), M (metering), and D (bus-tie). Any combination of these modules can be assembled in one cabinet lineup, and additional modules can be added later for expansion without replacing existing equipment.
What are the electrical ratings of the Dis Sub-12?
The Dis Sub-12 is rated 12kV, 50Hz, with 1250A rated current on the main circuit. Short-time withstand current is 31.5kA/4s (main) and 27.4kA/2s (earth circuit). Peak withstand current is 80kA (main) and 68.5kA (earth circuit). Short-circuit breaking current is 31.5kA. Power frequency withstand voltage is 42kV (phase-earth) and 48kV (isolated fracture), and lightning impulse withstand voltage is 75kV (phase-earth) and 85kV (isolated fracture).
What is the delivery time and MOQ?
Standard configurations ship within 30-60 days from order confirmation. MOQ is 1 unit. Custom voltage ratings, protection schemes, or integrated FTU configurations may require 60-90 days. We accept sample orders for validation testing.
How does it compare to the SF6-free gas-insulated RMU?
Both are SF6-free, but the insulation medium differs. The air-insulated Dis Sub-12 uses air for insulation — simpler maintenance, fully recyclable, no sealed gas tank. The SF6-free gas-insulated RMU uses dry air and eco-friendly mixed gas sealed in an IP67 stainless steel tank — more compact for higher voltages and requiring no periodic gas monitoring. Choose air-insulated for 12kV and box substations; choose gas-insulated for higher voltage or extreme environments. See SF6-free gas-insulated RMU →
Related Equipment
For a complete air-insulated distribution solution, pair the Dis Sub-12 with:
- SF6-Free Gas-Insulated RMU — For higher voltage or extreme-environment applications
- 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
500mm cabinet width per module
12kV / 1250A / 31.5kA ratings
Air-insulated — no gas, no emissions
Fixed vacuum CB + three-station switch
Pressure relief channels front & rear
Modular C/F/V/PT/M/D configurations
Ready to Specify Your Air-Insulated 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 Air-Insulated vs Gas-Insulated RMU →
Hot Tags: 12kv air insulated rmu, compact ring main unit manufacturer, air insulated switchgear supplier, 500mm width switchgear, fixed vacuum circuit breaker rmu, modular switchgear for box substation
Related Category
Send Inquiry
Contact Info
-
Address
Luotuo Industrial Area, Zhenhai District, Ningbo City, China
-
-
Email
Tell us your requirements and our specialists will provide a tailored solution for your power distribution or energy system project.
Our team will reply within 24 hours.
