- RING MAIN UNITS (RMUS)
Compact HV Switching for Grid-Connected Sites
Reliable ring main units for high-voltage distribution at renewable energy project grid connection points — with full DNSP interface management.
PRODUCT OVERVIEW
The HV Switching Solution for Australian Renewable Projects
Ring Main Units (RMUs) are compact, gas-insulated medium-voltage switchgear used at the grid connection point of renewable energy projects. GreenBox supplies, specifies and coordinates the installation of RMUs for solar farms, C&I sites and utility interconnections across Australia.
We manage the full interface with the DNSP and provide all required documentation — from specification review and protection relay coordination through to energisation sign-off. Our team removes the HV interface complexity from your project scope entirely.
Available in 2-way to 4-way configurations for 11kV and 22kV networks, with optional built-in protection relay for earth fault, overcurrent and auto-reclose functionality.
Technical Specifications
Voltage Rating
11kV / 22kV
Current Rating
630A
Breaking Capacity
12.5kA
Insulation
SF6 Gas
Configuration
2-way to 4-way
Protection
Built-in relay (optional)
Standards
IEC 62271-200
IP Rating
IP3X minimum
GreenBox Scope
- RMU specification and procurement
- DNSP technical submission management
- Protection relay coordination
- Installation supervision
- Primary injection testing
- Energisation documentation
VOLTAGE RATING
11-
11
kV
CURRENT RATING
0
A
BREAKING CAPACITY
0
.5kA
INSULATION
SF
0
KEY FEATURES
Technology and Service, Combined
Gas Insulated Technology
SF6 gas insulation provides superior dielectric performance in a compact footprint — eliminating the need for large air-insulated switchgear rooms.
Compact Footprint
Pad-mount RMU configuration minimises civil works and land area requirements at the grid connection point — critical for constrained urban and rural sites.
DNSP Interface Management
GreenBox manages the full technical and commercial interface with the DNSP — from specification review through to energisation sign-off.
Protection Relay Integration
Optional built-in protection relay for earth fault, overcurrent and auto-reclose functionality — reducing the need for external relay panels.
Full Commissioning Support
Our team coordinates primary injection testing, relay commissioning and DNSP witness testing — ensuring compliant energisation from day one.
Lifecycle Documentation
IEC 62271-200 type test certificates, routine test reports, operating manuals and maintenance schedules supplied with every unit.
APPLICATIONS
Deployed Across C&I Renewable Projects
Solar Farm POC Switchgear
The most common RMU application in Australia — providing the HV switching and protection function at the solar farm point of connection to the DNSP network.
Industrial HV Connection
Industrial facilities connecting at 11kV or 22kV use RMUs as the primary switching and protection device at the incoming HV switchboard.
Utility Network Extension
DNSPs use RMUs to extend ring distribution networks to new connection points — maintaining network redundancy and switching flexibility.
Battery Storage HV Interface
Utility-scale BESS projects require an HV switching device at the grid connection point — RMUs are the preferred solution for their compact size and reliability.
BENEFITS
Why Engage GreenBox for Your RMU
DNSP Coordination Included
Our team manages the full DNSP technical approval process — including RMU specification review, protection relay coordination and energisation documentation — removing the complexity from your scope.
Proven Technology
SF6 gas-insulated RMUs have a decades-long track record in Australian utility networks. IEC 62271-200 type-tested equipment provides bankable reliability for asset owners and financiers.
Reduced Civil Works
Compact pad-mount RMU configurations eliminate the need for purpose-built switchgear rooms, reducing civil cost and programme risk at the grid connection point.
FAQ
RMU Questions
Our HV engineering team is available to advise on RMU specification, DNSP requirements and project-specific applications.
Does GreenBox supply the RMU directly or manage procurement?
GreenBox manages the full RMU supply — specifying the unit to your project requirements, procuring from approved manufacturers, and coordinating delivery and documentation. We work with established RMU manufacturers whose equipment has DNSP acceptance across Australian networks.
How does GreenBox manage the DNSP interface for RMU projects?
Our team handles the complete DNSP interface — including preparation of technical specifications for DNSP review, response to technical queries, coordination of protection relay settings, and management of the energisation application. This is included in our project management service.
Can GreenBox coordinate RMU installation and commissioning?
Yes. We coordinate installation supervision, primary injection testing of protection relays, DNSP witness test attendance, and preparation of commissioning reports. Our team manages the full energisation process through to successful HV connection.
What maintenance is required for SF6 gas-insulated RMUs?
SF6 RMUs are largely maintenance-free under normal operating conditions. Routine inspections typically include SF6 gas pressure checks, visual inspection of external components and mechanism verification — typically every 5 years or in accordance with the manufacturer’s schedule. We supply the full maintenance manual with each unit.
What warranty do RMUs carry?
RMUs are supplied with the manufacturer’s standard warranty, typically 2 years on the complete unit. GreenBox provides a 12-month workmanship warranty on all coordination, specification and documentation services. Extended warranty arrangements can be discussed for large-scale or multi-unit projects.