A Ring Main Unit (RMU) is a compact, fully enclosed, and gas-insulated switchgear system used in secondary distribution networks. It serves as a critical component for managing medium-voltage power distribution by ensuring reliable switching and protection of electrical circuits.
An RMU integrates different types of switching devices, including:
These units generally operate at voltage levels up to 24kV and current ratings up to 630A. The core structure remains similar across different voltage ranges, with higher voltage levels requiring increased gas pressure for insulation.
Gas-insulated RMUs (rated up to 36kV) are widely used in secondary distribution systems due to their compact design and robust performance in various environments, including wind farms, transformer substations, and industrial facilities.
Key Features:
✅ Compact & Space-Saving: Designed for both indoor and outdoor installations.
✅ High Operator Safety & Reliability
✅ Resistant to Pollution, Humidity, and High Altitude
✅ Low Maintenance & Long Service Life
✅ Expandable Design: Can be extended on one or both sides.
✅ Remote Monitoring & Control
✅ Compliance with IEC & EN Standards
Oil-insulated-RMU[/caption]
This type of RMU is ideal for harsh and corrosive environments, such as oil fields and mining applications. It features a compact yet expandable design with modular ring switches and fused circuit breakers.
Key Features:
✅ Robust, IP54-Rated Enclosure: Withstands extreme temperatures (-10°C to 55°C) and 100% humidity.
✅ Flexible Installation: Side and rear cable termination for easy commissioning.
✅ SCADA Compatibility: Can be integrated into remote monitoring systems.
✅ Safety Mechanisms: Equipped with interlocking and padlocking for secure operation.
✅ Voltage & Current Ratings: 15.5kV, 630A, 50Hz.
Air-insulated RMUs are metal-enclosed switchgear commonly used in residential complexes, high-rise buildings, factories, and businesses. They feature a vacuum load switch as the primary switch.
Key Features:
✅ Environmentally Friendly & High Insulation Strength
✅ Modular Design: Easy to install and operate.
✅ Reliable Performance: Built for harsh operating conditions.
✅ Strong Interlocking System: Ensures safety and compliance with protection standards.
✅ Cost-Effective & Compact
outdoor installation[/caption]
Outdoor RMUs (typically rated 13.8kV) are widely used in urban and rural power distribution for utilities, commercial buildings, hospitals, airports, and metro systems.
Key Features:
✅ Vacuum Circuit Breaker for High Durability
✅ Maintenance-Free & Pedestrian-Safe (No exposure to active parts)
✅ Integrated Safety Interlocks
✅ Remote Monitoring & Control Support
✅ Eco-Friendly & Recyclable
Indoor RMUs are SF6-insulated switchgear designed for secondary distribution networks. They are compact, easy to install, and require minimal maintenance.
Key Features:
✅ Fully Insulated with SF6
✅ Available with Switch Disconnectors, Fuses, and Circuit Breakers
✅ Rated Voltage: 12kV, 17.5kV, 24kV
✅ Rated Current: 630A
✅ Remote Monitoring Capabilities