As the power industry moves toward more sustainable technologies, SF₆-free Ring Main Units (RMUs) are becoming an increasingly important solution for modern medium voltage power distribution.
Traditional gas-insulated switchgear has widely used SF₆ because of its excellent electrical insulation properties. However, SF₆ has a very high global warming potential, encouraging the development of alternative insulation technologies.
Today, SF₆-free RMUs using alternative insulation media such as clean air or nitrogen provide an environmentally responsible option for applications including renewable energy, EV charging infrastructure, industrial facilities and utility distribution networks.
An SF₆-free RMU is a medium voltage Ring Main Unit that does not use sulfur hexafluoride (SF₆) as its insulating medium.
Depending on the equipment design, alternative media such as clean air or nitrogen can be used for insulation.
Like conventional RMUs, an SF₆-free RMU can integrate switching, isolation, protection and distribution functions into a compact enclosure.
This makes it suitable for secondary medium voltage distribution systems where reliability, compact design and environmental performance are important.
Common applications include:
- Utility distribution networks
- Solar power plants
- Wind power projects
- Industrial facilities
- Commercial buildings
- EV charging infrastructure
- Smart distribution systems
SF₆ has excellent insulating properties and has traditionally been used in gas-insulated electrical equipment. However, its high global warming potential has led the power industry to explore alternatives.
As utilities, EPC contractors, renewable energy developers and industrial users pay more attention to sustainable power infrastructure, SF₆-free switchgear is becoming increasingly relevant.
When selecting medium voltage equipment, customers may now consider not only electrical performance and cost, but also:
- Environmental impact
- Insulation technology
- Equipment reliability
- Maintenance requirements
- Installation environment
- Communication capabilities
- Future expansion
For projects with sustainability objectives, an eco-friendly RMU can therefore be an attractive alternative to conventional SF₆-insulated equipment.
The most important feature is the use of alternative insulation technology instead of SF₆.
Depending on the configuration, clean air or nitrogen can be used as the insulating medium, reducing dependence on SF₆.
Gas-insulated RMUs integrate multiple medium voltage functions into a compact structure.
This can help save installation space, making RMUs suitable for applications such as urban distribution networks, industrial plants, solar projects and EV charging stations.
Modern RMUs use sealed compartments to protect internal electrical components from external environmental conditions.
For applicable configurations, certain RMU compartments can provide IP67 protection, helping the equipment operate reliably in environments with dust or moisture.
Different projects have different electrical requirements. An SF₆-free RMU can be configured according to factors such as:
- Rated voltage
- Rated current
- Feeder arrangement
- Short-circuit requirements
- Protection requirements
- Communication functions
- Installation environment
The final configuration should always be selected according to the specific project requirements.
Medium voltage distribution systems operate at different voltage levels depending on the country and electrical network.
The appropriate rated voltage is therefore one of the first factors to consider when selecting an RMU.
The GHXGEN Series can be configured for 12kV and 24kV applications, with rated current options of up to 630A or 1250A depending on configuration.
When selecting a 12kV or 24kV RMU, engineers should consider:
- Rated voltage
- Rated current
- Short-circuit withstand capability
- Transformer capacity
- Number of feeders
- Protection requirements
- Communication requirements
- Installation conditions
Solar power plants require reliable medium voltage equipment to connect transformers, feeders and the grid.
An SF₆-free RMU for solar power plants can provide switching, isolation and protection functions within the medium voltage network.
For renewable energy projects with sustainability objectives, SF₆-free technology can provide an environmentally responsible option.
Large EV charging stations and fleet charging facilities may require medium voltage equipment to connect charging systems to the utility network.
An RMU can provide:
- Medium voltage distribution
- Transformer connection
- Feeder switching
- Fault isolation
- Protection
- Monitoring
A compact SF₆-free RMU for EV charging infrastructure can therefore be considered for large charging projects.
Factories and industrial parks often require stable medium voltage power for production equipment and internal distribution systems.
RMUs can provide switching and protection between incoming power supplies, transformers and outgoing feeders.
Typical applications include manufacturing plants, industrial parks, mining facilities and large infrastructure projects.
RMUs are widely used in secondary medium voltage distribution networks.
They can help utilities manage feeders, isolate faults and improve network flexibility. When combined with communication and monitoring systems, smart RMUs can also support distribution automation.
Modern power distribution systems are becoming increasingly digital.
A smart RMU can integrate switching equipment with monitoring, protection and communication functions.
Depending on the configuration, RMU systems can support communication protocols such as IEC 61850 and Modbus.
IEC 61850 is an international standard used for communication and automation in power utility systems.
It enables intelligent electrical equipment to exchange information with protection, control and automation systems, making it useful for smart substations and automated distribution networks.
Modbus is widely used in industrial automation and electrical monitoring systems.
Depending on the project configuration, Modbus can connect RMU monitoring and control functions with supervisory or industrial automation systems.
For smart distribution projects, communication requirements should therefore be considered during the initial equipment selection.
The GHXGEN Series is Changyun Intelligent's eco-friendly gas-insulated RMU solution for modern medium voltage distribution.
The series uses an SF₆-free insulation concept, with clean air or nitrogen available depending on the selected configuration.
Key features include:
| Parameter | GHXGEN Series |
|---|---|
| Insulation | Clean Air / Nitrogen |
| SF₆ | SF₆-free |
| Rated Voltage | 12kV / 24kV |
| Rated Current | Up to 630A / 1250A depending on configuration |
| Protection | Up to IP67 depending on configuration |
| Communication | IEC 61850 / Modbus depending on configuration |
| Applications | Utility / Renewable Energy / Industrial / EV Charging |
The exact configuration can be customized according to project requirements.
Before selecting an eco-friendly medium voltage RMU, customers should consider:
Rated Voltage: Determine whether the system requires 12kV, 24kV or another medium voltage rating.
Rated Current: Select the appropriate current according to the expected load.
Short-Circuit Requirements: Ensure the RMU meets the required short-circuit withstand and protection requirements.
Feeder Configuration: Determine the number and type of incoming and outgoing feeders.
Protection: Select suitable protection equipment based on the transformer and network requirements.
Communication: Consider IEC 61850, Modbus or other communication requirements for smart distribution systems.
Installation Environment: Indoor and outdoor applications may require different enclosure and protection solutions.
Future Expansion: Consider future capacity increases when designing the distribution system.
The growth of renewable energy, EV charging and smart grids is changing the requirements for medium voltage switchgear.
Customers increasingly want equipment that combines reliable electrical performance, compact design, environmental considerations and digital communication.
As a result, SF₆-free RMU technology is becoming increasingly relevant for:
- Renewable energy projects
- Solar and wind power
- EV charging infrastructure
- Industrial distribution
- Utility networks
- Smart grids
SF₆-free RMUs provide an alternative solution to conventional SF₆-insulated medium voltage switchgear.
By using alternative insulation technologies such as clean air or nitrogen, these RMUs can combine the compact advantages of gas-insulated equipment with reduced reliance on SF₆.
For solar power plants, EV charging infrastructure, industrial facilities and utility distribution networks, SF₆-free RMUs can provide a flexible option for modern medium voltage power distribution.
The GHXGEN Series is available in 12kV and 24kV configurations, with options for smart communication, applicable IP67 protection and customized feeder arrangements depending on project requirements.
If you are looking for an SF₆-free RMU, 12kV/24kV medium voltage RMU or customized switchgear solution, contact Changyun Intelligent to discuss your project requirements.
An SF₆-free RMU is a medium voltage Ring Main Unit that does not use SF₆ as its insulating medium. Depending on the design, clean air or nitrogen can be used as an alternative.
The main difference is the insulation technology. SF₆ RMUs use sulfur hexafluoride, while SF₆-free RMUs use alternative insulation technologies.
Yes. SF₆-free RMUs can be used in medium voltage distribution systems for solar projects, subject to the project's electrical and protection requirements.
Yes. RMUs can be used for medium voltage distribution, transformer connection, switching and protection in large EV charging infrastructure projects.
Yes. The GHXGEN Series can be configured for 12kV and 24kV applications according to project requirements.
Depending on the selected configuration, smart RMU solutions can support communication protocols such as IEC 61850 and Modbus.
