1.Product Overview
The Ring Main Unit (RMU) is a modular, compact medium-voltage switchgear device primarily used for ring-network power supply, branch line protection, and power distribution in electrical systems. Its structure typically consists of load switches, circuit breakers, fuses, earthing switches, and instrument transformers, utilizing SF6, vacuum, or solid insulation technology to ensure high reliability and safety.
Ring Main Unit (RMU) are widely applied in urban power grids, industrial parks, commercial complexes, data centers, and renewable energy power stations, particularly in space-constrained environments. Compared to traditional switchgear, RMUs are more compact, easier to maintain, and support smart upgrades (e.g., integration with DTU and SCADA systems) for remote monitoring and automated operation.
Modern Ring Main Unit (RMU) emphasize environmental sustainability, with some models replacing SF6 gas with dry air or solid insulation to reduce greenhouse gas emissions. Additionally, the modular design allows flexible expansion and modification to meet diverse power distribution needs.
2. Product Functions
(1) Ring-Network Power Supply
Supports dual or multiple power sources for uninterrupted power supply.
Uses load switches to switch power paths, improving supply reliability.
(2) Short-Circuit and Overload Protection
Utilizes fuses or circuit breakers to interrupt fault currents rapidly.
Works with relay protection devices for overload and earth fault protection.
(3) Load Switch and Circuit Breaker Combined Control
Load switches handle normal current switching, while circuit breakers manage fault current interruption.
Configurable as “load switch + fuse” combination for cost-effective solutions.
(4) Fault Isolation and Restoration
Automatically detects and isolates faulty sections, restoring power to unaffected areas.
Supports manual or motorized operation for different application scenarios.
(5) Smart Control (Optional)
Integrates DTU (Distribution Terminal Unit) for remote monitoring and control.
Compatible with SCADA systems for automated power distribution management.
3.Product Features
(1) Compact and Modular Design
Small footprint, ideal for confined spaces.
Modular structure for easy expansion and maintenance.
(2) High Reliability
Uses SF6, vacuum, or solid insulation for superior arc resistance.
Fully enclosed structure, resistant to dust and moisture for harsh environments.
(3) Smart-Ready (Optional)
Supports DTU/FTU integration for “three-remote” functions (telemetry, telecontrol, telesignaling).
Complies with IEC 61850 for seamless smart grid integration.
(4) Eco-Friendly and Safe
Some models use dry air or solid insulation, eliminating SF6 emissions.
Five-interlock mechanism prevents misoperation.
(5) Easy Maintenance
Low or maintenance-free design reduces operational costs.
Transparent window for visual switch status inspection.
(6) Wide Applicability
Suitable for urban grids, industrial, commercial, and renewable energy applications.
Customizable designs for specialized requirements.
This document provides a comprehensive technical overview of the Ring Main Unit (RMU), serving as a reference for power system design, selection, and maintenance.
Product Parameters
Rated Voltage:12kV / 24kV / 40.5kV
Rated Current:630A / 1250A / 2500A
Short-Circuit Breaking Capacity:20kA / 25kA / 31.5kA
Power Frequency Withstand Voltage:42kV / 65kV / 95kV (1min)
Lightning Impulse Withstand Voltage:75kV / 125kV / 185kV
Mechanical Life:10,000 operations (load switch)
Protection Level:IP67 (gas compartment) / IP4X (cabinet)
Insulation Medium:SF6 / Vacuum / Dry Air / Solid
Operation Mode Manual: Motorized / Spring-Operated
