Primary & Secondary Integrated Ring Main Unit (Smart RMU)

The Primary & Secondary Integrated Ring Main Unit (RMU) combines medium-voltage primary switchgear with intelligent secondary protection, control, monitoring and communication functions in one compact factory-assembled solution.

Designed for 12kV and 24kV distribution networks, it enables reliable power distribution, load switching, intelligent fault detection, fast fault isolation and automatic service restoration. The integrated design significantly improves distribution automation efficiency while reducing installation time and lifecycle costs.

The primary switchgear and secondary protection, control and communication modules are fully integrated, pre-wired and factory tested before delivery.

Compared with conventional RMUs, the integrated solution offers:

• Plug-and-play installation
• No on-site secondary wiring
• Reduced engineering and commissioning workload
• Over 70% reduction in installation and commissioning costs
• Faster project delivery

The fully insulated, hermetically sealed design protects all live parts from environmental influences.

Benefits include:

• Excellent performance in humid, dusty and highly polluted environments
• Maintenance-free sealed insulation system
• Cabinet width only 350–500 mm, maximizing space utilization
• Ideal for urban distribution networks, compact substations and retrofit projects

The integrated intelligent controller provides comprehensive feeder protection and supports modern smart grid applications.

Functions include:

• Battery-free self-powered protection without external auxiliary power
• Overcurrent protection
• Instantaneous short-circuit protection
• Zero-sequence earth fault protection
• Automatic reclosing
• Feeder Automation (FA) for rapid fault location, isolation and service restoration
• Optional DTU/FTU intelligent terminal
• Supports IEC 60870-5-101, IEC 60870-5-104 and Modbus communication protocols
• Seamless integration with SCADA and distribution management systems (DMS)

Designed to maximize operator safety while simplifying daily operation and maintenance.

Features include:

• Internal arc-resistant design
• Independent pressure relief channels
• Mechanical and electrical five-interlock safety system
• Optional motorized operating mechanism
• Local and remote operation
• One-touch sequential switching control

The Primary & Secondary Integrated RMU is widely used in modern medium-voltage distribution systems, including:

• Urban distribution networks
• Residential communities
• Commercial buildings
• Industrial parks
• Manufacturing facilities
• Mining operations
• Prefabricated substations
• Switching stations
• Outdoor compact substations
• Renewable energy projects including photovoltaic (PV) and wind farms
• Smart grid and distribution automation projects

• Compact all-in-one integrated design
• Factory assembled, pre-tested and ready for installation
• Supports smart grid and distribution automation
• Reduced installation time and engineering costs
• High operational reliability with maintenance-free sealed construction
• Compatible with IEC communication protocols
• Suitable for both utility and industrial distribution applications
• Available in 12kV and 24kV configurations with customized solutions

A Primary & Secondary Integrated Ring Main Unit (Smart RMU) integrates medium-voltage primary switchgear with secondary protection, control, monitoring and communication systems into one compact factory-assembled unit. It simplifies installation while improving distribution automation, operational reliability and maintenance efficiency.

Our Primary & Secondary Integrated RMUs are available in 12kV and 24kV configurations. Other customized specifications can be provided according to project requirements.

The integrated controller supports industry-standard communication protocols, including:

• IEC 60870-5-101
• IEC 60870-5-104
• Modbus

It can be seamlessly integrated with SCADA, Distribution Management Systems (DMS) and utility distribution automation platforms.

Yes. The Smart RMU supports Feeder Automation (FA), enabling rapid fault detection, fault isolation and automatic restoration of power to healthy sections, significantly improving power supply reliability.

Yes. It is equipped with a battery-free self-powered protection system, eliminating the need for an external auxiliary power supply while ensuring reliable protection functions.

Yes. We provide OEM and project-specific customization based on customer requirements, including different panel configurations, communication systems, protection schemes, operating mechanisms and enclosure designs.

It is widely used in:

• Urban power distribution networks
• Residential communities
• Commercial buildings
• Industrial parks
• Manufacturing plants
• Mining facilities
• Prefabricated substations
• Renewable energy projects such as photovoltaic (PV) and wind farms
• Utility distribution automation projects

• Compared with traditional RMUs, the integrated solution offers:
• Factory pre-assembled and fully tested
• No on-site secondary wiring
• Faster installation and commissioning
• Lower engineering and labor costs
• Improved system reliability
• Easier maintenance
• Better support for smart grid and distribution automation

The RMU is designed and manufactured in accordance with applicable IEC standards. Specific compliance (such as IEC 62271 series) and project-specific requirements can be provided upon request.

Changyun has over 17 years of manufacturing experience in medium-voltage power distribution equipment. We provide:

• Factory-direct pricing
• Strict quality control
• OEM & ODM services
• Technical support
• Fast delivery
• Customized solutions for utility, industrial and renewable energy projects worldwide