Shenheng Power Equipment Co., Ltd.
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Ring Main Unit RMU SF6 Gas Insulated MV Switchgear
The Ring Main Unit (RMU), also widely known as the SF6 gas insulated cabinet, is a professional medium-voltage high-performance electrical switchgear. It adopts high-purity SF6 sulfur hexafluoride gas as the core insulating and arc-extinguishing medium, replacing traditional air insulation structures. Featuring miniaturized size, fully enclosed protection, maintenance-free operation and ultra-long service life, this MV switchgear delivers stable, safe and efficient power distribution performance. It is widely applicable to urban power grids, industrial power supply, new energy grid connection and other core scenarios, being a mainstream reliable solution for modern medium-voltage power distribution systems.
Product Overview
The SF6 gas insulated Ring Main Unit (RMU) is a specialized medium and high voltage electrical equipment designed for modern power distribution systems. Different from conventional air-insulated switchgears, it takes inert SF6 gas as the exclusive insulating and arc-quenching medium, which can quickly extinguish electric arcs and isolate circuits safely. This core technical design fundamentally optimizes the structural performance and operational stability of the equipment, enabling the RMU switchgear to adapt to diverse complex power distribution environments and meet the high-standard power supply demands of various industries.
Core Product Advantages
1.Ultra-Miniaturized Structure, Space-Saving
Benefiting from the excellent high-insulation performance of SF6 gas, the overall volume of the RMU gas cabinet is reduced by more than 50% compared with traditional air-insulated distribution cabinets. The compact and integrated structural design greatly saves installation space, making it perfectly suitable for scenarios with strict space limitations.
2.All-Weather Operational Reliability
The equipment adopts a fully sealed enclosed structure, which completely isolates internal core components from the external environment. It is not affected by harsh factors such as high humidity, dust pollution, corrosive dirt and high altitude, ensuring consistent and stable operating performance in various complex working conditions.
3.Completely Maintenance-Free Operation
SF6 gas boasts extremely high chemical stability and inert characteristics. The internal conductive contacts and core components work in a stable inert gas environment, with almost no oxidation, wear or aging. It effectively eliminates the need for frequent daily maintenance and component replacement, greatly reducing later operational costs.
4.30+ Years Ultra-Long Service Life
With mature structural design, high-quality raw materials and stable gas insulation system, the RMU switchgear achieves a design service life of more than 30 years. It supports long-term continuous and stable operation, providing durable power distribution guarantee for projects.
5.High Safety & Low Noise Operation
The product features flame-retardant and fire-proof performance with zero fire risk during operation. Meanwhile, the optimized internal structural design effectively reduces operating noise, realizing safe, silent and environmentally friendly equipment operation.
Wide Application Scenarios
Power Substations: Ideal for incoming lines, outgoing lines and bus connection circuits of medium and high voltage power distribution systems, ensuring stable power transmission and circuit protection for grid substations.
Industrial Power Supply: Adaptable to harsh industrial environments including mining, metallurgy, chemical engineering and other high-corrosion, high-dust working scenarios, meeting high-reliability industrial power consumption demands.
Urban Power Grid Construction: Perfect for space-limited key urban facilities such as subways, airports and large-scale data centers, supporting precise and efficient urban power distribution.
Renewable Energy Projects: Applicable to voltage boosting and grid connection links of photovoltaic power stations and wind farms, adapting to fluctuating new energy power generation loads and realizing stable grid integration.
| No. | Item | Unit | Technical Parameter |
|
| 1 | Rated voltage | KV | 12 | |
| 2 | Rated current | A | 1250 | |
| 3 | Rated short-time power frequency withstand voltage (effective value) | KV | 42 | |
| 4 | Rated lightning impulse withstand voltage (peak value) | KV | 75 | |
| 5 | Rated short-circuit breaking current (effective value) | KA | 31.5 | |
| 6 | Rated short-circuit making current (peak value) | KA | 80 | |
| 7 | Rated thermal stability current(effective value) |
Main circuit (4S) | KA | 31.5 |
| Ground loop (4S) | KA | 27.3 | ||
| 8 | Rated dynamic stabilitycurrent (peak value) |
Main circuit | KA | 80 |
| Ground loop | KA | 68.3 | ||
Customization & Standardization Advantages
To meet diverse project demands, our RMU SF6 gas cabinet supports free selection of international famous brand components including ABB and Siemens. We provide full-coverage ODM and OEM customized services, and the entire product series strictly complies with the international standard IEC 62271-200, ensuring universal compatibility and authoritative quality certification for global projects.
Intelligent Production Strength
We are equipped with more than 220 sets of advanced intelligent production equipment, building a fully automated production cluster. The production line supports 72-hour unattended continuous operation, with a capacity utilization rate of over 95%. The intelligent manufacturing mode effectively improves production efficiency and product consistency, shortening the overall order delivery cycle by 30% and realizing fast and high-quality order delivery.
Strict Quality Control System
All equipment will undergo a full set of professional project tests and 72-hour continuous operation inspection before factory delivery. We strictly verify the operational stability of the equipment in extreme environments to eliminate potential quality risks. Backed by reliable quality performance, we provide an ultra-long 30-year quality protection commitment for all products.
Global Full-Cycle Service
We provide 24/7 global customer response service, quickly responding to technical consultation, after-sales support and project customization needs of customers worldwide. Meanwhile, we provide customized full life cycle maintenance solutions, which can effectively extend the overall service life of equipment by 30%, creating long-term value for customers’ projects.
Engineering Scope and Selection Inputs
An RMU should be evaluated from the cable network layout, required switching and protection functions, installation environment, and operating procedure. Confirm the exact module arrangement and gas-handling obligations for the project location.
Related Engineering Reading
Ring Main Unit Selection Guide · SF6 RMU Outdoor Installation Guide
For an engineering review, contact Shenheng Power with the approved single-line diagram, site conditions, required standards, and delivery requirements.
B2B Manufacturing: OEM Solutions for Distributors
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Customized transformers, switchgear, ring main units, prefabricated substations and electrical components for project requirements, technical specifications and market applications.
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We provide flexible configuration support for transformers, switchgear, ring main units, prefabricated substations and related electrical components.
Stable Manufacturing Capability
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Complete Service System
From early communication to production follow-up and after-sales support, we provide responsive service for customers and project partners.
Manufacturing & Quality Control
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Application Areas
Power distribution solutions serving industrial, commercial and infrastructure projects.
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Industrial Plants & Mining
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Commercial Buildings & Infrastructure
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EV Charging Infrastructure
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View MoreFrequently Asked Questions
What is SF6 RMU?
SF6 RMU stands for Sulfur Hexafluoride Ring Main Unit. It is a compact, modular medium‑voltage switchgear that uses SF6 gas for both insulation and arc extinction. It is commonly deployed in urban power distribution networks for ring or radial feeder configurations.
Which gas is used in RMU?
SF6 is the traditional insulating and quenching gas for RMUs. However, due to environmental concerns, manufacturers are increasingly using alternatives such as dry air or nitrogen in newer eco‑designs.
What is the difference between RMU and switchgear?
An RMU is a specific subset of switchgear. It is designed primarily for ring‑main applications and typically employs load‑break switches and fuses. In contrast, “switchgear” is a general term that covers a wide range of switching and protection devices, including those with circuit breakers capable of handling higher fault currents and more complex control functions.
What is SF6 gas‑insulated switchgear?
SF6 gas‑insulated switchgear (GIS) is an assembly in which all live components – such as busbars, circuit breakers, and disconnectors – are enclosed in a sealed metal housing filled with SF6 gas. This design takes advantage of SF6’s high dielectric strength to reduce equipment size and render the apparatus immune to ambient contamination and humidity.
What are the key differences between air‑insulated and gas‑insulated switchgear?
The fundamental difference lies in the insulation medium. Air‑insulated switchgear (AIS) relies on ambient air, which makes it less expensive and easier to inspect and modify, but it requires larger clearances and is sensitive to pollution and moisture. Gas‑insulated switchgear (GIS) uses pressurized pure gas (e.g., SF6) inside a sealed enclosure, offering a much smaller footprint, superior reliability, and full immunity to external environmental conditions, at a higher manufacturing and maintenance cost.
What are the advantages and disadvantages of gas‑insulated switchgear?
The main advantages are its compact footprint, high operational reliability owing to the sealed construction, and enhanced personnel safety because all energized parts are enclosed. The primary disadvantages are the high global‑warming potential of SF6 gas and the relatively high initial investment and specialised handling required during manufacturing and end‑of‑life disposal.
What are the three types of switchgear?
Although switchgear can be classified in various ways, one common categorisation based on insulation medium distinguishes three types: air‑insulated switchgear (AIS), gas‑insulated switchgear (GIS), and hybrid switchgear (MTS) which combines elements of both technologies to balance performance and cost.
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