Environment-Friendly Pure Air Insulated Ring Main Unit Overall Application Solution

Project Background and Technical Challenges

With the advancement of global energy transition and the carbon peaking and carbon neutrality goals, medium-voltage distribution network equipment is accelerating the upgrade towards non-fluorinated, environment-friendly, compact and intelligent development. Traditional SF₆ insulated ring main units face stringent environmental constraints and high costs in procurement, operation and maintenance, scrapping and recycling due to their high Global Warming Potential (GWP). Conventional air-insulated switchgears have inherent shortcomings such as low insulation margin, vulnerability to dampness and condensation, weak protection level and large footprint. They can no longer meet the core requirements of urban distribution networks, underground power distribution rooms, industrial parks, new energy stations and overseas power grids for high reliability, maintenance-free operation and green low-carbon development.

Main technical challenges faced by current distribution network applications:

• Environmental compliance requirements are increasingly stringent, resulting in high full-lifecycle management costs and complicated disposal procedures for SF₆.
• Space is limited in urban core areas, old community renovation projects and underground substations, creating an urgent demand for compact equipment.
• Insulation stability cannot be guaranteed in harsh environments with high humidity, heavy salt spray, high dust and high altitude.
• Traditional equipment lacks intelligent status monitoring functions and relies on routine inspections for passive maintenance.
• Distribution network renovation projects require compatible interfaces, efficient deployment and uninterrupted power switching.

Overall Solution Architecture

Targeting the 12kV medium-voltage distribution network system, this solution provides a complete set of environment-friendly ring main unit solution adopting dry pure air (Pure Air) as the sole insulating medium. By adopting optimized electric field design, fully enclosed sealed gas chamber, integrated mechanism and primary-secondary fusion intelligent measurement and control technology, it establishes a reliable power supply system integrating ring network power supply, load control, fault isolation and status monitoring, and realizes the unification of environmental performance, operational reliability and engineering economy.

Core Technical Principle

Filtered, dried and pressure-stabilized pure air is adopted as the insulating medium, without using SF₆ or other alternative gases. Optimized electrode structure and electric field homogenization design are applied to improve the insulation utilization coefficient. A fully enclosed welded gas chamber and long-term sealing technology ensure long-term internal dryness and stability, fundamentally avoiding faults such as condensation, dampness and flashover. Supported by integrated operating mechanism and intelligent measurement and control unit, the equipment realizes rapid operation, precise protection and real-time status perception.

Key Technical Parameters

Typical Application Scenarios

• Urban distribution network upgrading and renovation: Underground distribution rooms, old residential communities and commercial complex power distribution systems.
• Industrial power distribution system: Industrial parks, data centers and high-end manufacturing plants.
• New energy supporting system: Supporting box-type substations for photovoltaic, wind power and energy storage power stations.
• Harsh environment application: Coastal salt spray areas, humid rainy regions, alpine and high-altitude areas.
• Overseas power grid projects: Regions with strict environmental access requirements including the EU, Southeast Asia, the Middle East and Australia.

Engineering Implementation and Deployment

• On-site investigation and solution design: Formulate configuration and installation schemes according to power distribution topology, space conditions and load characteristics.
• Modular integrated supply: Delivered as complete factory-assembled units with pre-commissioned integration to reduce on-site assembly workload.
• Standardized interface installation: Compatible with foundation and cable interfaces of traditional ring main units for convenient construction.
• Uninterrupted power renovation: Support in-situ replacement with minimal impact on user power supply.
• System joint debugging and acceptance: Complete function test, insulation test, protection verification and communication joint commissioning.

Project Value and Benefit

Environmental Value

• Adopting natural air insulation achieves zero greenhouse gas emissions without recycling and disposal pressure, fully complying with the requirements of green power grids and low-carbon development.

Operational Value

• The fully enclosed and dry gas chamber maintains stable insulation performance, greatly reducing the incidence of insulation faults and improving the power supply reliability of distribution networks.

Economic Value

• Compact structure reduces civil engineering and space investment; no need for air refilling, leakage inspection or gas treatment, lowering the full-lifecycle operation and maintenance cost.

Management Value

• Support online equipment status monitoring and fault early warning, promoting the maintenance mode transformation from scheduled maintenance to condition-based maintenance.

Applicable Standards and Specifications

• GB/T 11022, Common Specifications for High-Voltage Switchgear and Controlgear
• GB/T 3906, 3.6kV～40.5kV AC Metal-Enclosed Switchgear
• GB/T 28547, Technical Requirements for Environment-Friendly High-Voltage Switchgear
• IEC 62271-1, High-voltage Switchgear and Controlgear – Part 1: Common Specifications
• IEC 62271-200, AC High-Voltage Switchgear

Solution Summary

With the core features of non-fluorinated environmental protection, high-reliability insulation, compact integration and intelligent operation and maintenance, the pure air insulated ring main unit solution can fully replace traditional SF₆ insulated and ordinary air-insulated equipment. It is widely applicable to urban distribution network construction, industrial power supply, new energy supporting facilities and overseas power grid upgrading projects, serving as the mainstream technical solution for the green and intelligent development of medium-voltage distribution networks.