SF6 Gas Insulated Ring Main Unit | 12kV / 24kV RMU

Overview

The Ring Main Unit (RMU) is a compact, modular, and fully enclosed medium-voltage switchgear designed for reliable power distribution in 12kV and 24kV networks. It integrates load switches, vacuum circuit breakers, and earthing switches into a single metal-enclosed unit, ensuring safe and uninterrupted electricity supply for industrial, commercial, and utility applications.

The RMU is available in SF6 gas-insulated, solid-insulated, and SF6-free eco-friendly variants, so the insulation technology can be matched to project and environmental requirements.

Key Features

• Fully insulated and fully sealed design — primary circuits are enclosed in a sealed gas tank or solid insulation system, ensuring maintenance-free operation and high reliability.
• Compact and space-saving — minimal footprint with cabinet widths starting from 375mm, maximising space utilisation in substations and switch rooms.
• Flexible configuration — available in modular, extensible designs to support side-extension and top-extension configurations for easy system expansion.
• Robust construction — a shot-blasted, zinc-sprayed, and epoxy powder-coated enclosure ensures corrosion resistance and durability for harsh environments.
• Reliable interlocking system — mechanical interlocks between load switch, circuit breaker, and earthing switch guarantee safe operation and maintenance.
• Intelligent protection — equipped with self-powered electronic protection relays, earth fault indication, and remote control and signalling capabilities.
• Eco-friendly options — SF6-free models utilise environmentally friendly insulating gases, reducing carbon footprint and environmental impact.
• Three insulation technologies — SF6 gas-insulated, solid-insulated, or eco-friendly gas-insulated variants.

Technical Specifications

Applications

• Urban residential areas — reliable power supply for housing complexes and communities.
• Commercial buildings — shopping malls, office buildings, hotels, and business centres.
• Industrial facilities — industrial plants, mining enterprises, and manufacturing sites.
• Infrastructure projects — airports, railways, subways, tunnels, and highways.
• Renewable energy — wind farms and solar power stations.
• Public facilities — hospitals, stadiums, schools, and government buildings.
• Small substations and switch rooms — compact distribution substations, cable branch boxes, and box-type substations.

Installation Conditions

• Confirm the altitude of the site — the standard rating covers ≤ 2000m, with customisation available for higher altitudes.
• Confirm the ambient temperature range — the unit is rated for -45°C to +50°C.
• Select the enclosure protection rating appropriate to the location: IP4X for indoor installation or IP55 for outdoor options.
• Allow for the modular extensible design — plan for side-extension or top-extension if future system expansion is expected.
• The sealed design means no routine internal maintenance is required; ensure the enclosure remains undamaged to preserve the protection rating.

How to Select

• The rated voltage required — 12kV or 24kV, with customisation available.
• The rated current required — 630A or 1250A.
• The system frequency — 50Hz or 60Hz.
• The insulation technology — SF6 gas-insulated, solid-insulated, or eco-friendly gas-insulated.
• The number of ways and the configuration required (for example 2-way, 3-way or 4-way), and whether extensibility is needed.
• The protection and control functions required, including self-powered relays, earth fault indication and remote signalling.
• The enclosure protection rating and whether the installation is indoor or outdoor.

FAQ

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