Medium Voltage

Medium Voltage Ring Main Units

Built with Schneider Electric: RM6, SM6, FBX
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Standard Ring Main Units provide load-break switching and short-circuit protection for distribution transformers in MV ring networks. They are typically smaller than main RMUs and used at secondary distribution points, where they feed a single transformer or short cable spur.

Schneider Electric's RM6 (gas-insulated) and SM6 (air-insulated) compact RMUs are reference products in MV distribution worldwide, with sealed-for-life tank construction and standard fault-make / load-break ratings.

Schneider Electric Source

For full technical specifications, datasheets, and certifications, refer to Schneider Electric's official product range:

RM6, SM6, FBX

Medium Voltage Ring Main Unit

Key Features

  • Sealed-for-life SF6 tank or air-insulated
  • Standard 1, 2, 3, or 4-function configurations
  • Up to 24 kV, 630 A
  • Compact footprint for tight substations
  • Optional remote control and motorisation

Typical Applications

  • Compound and residential MV networks
  • Commercial building distribution
  • Industrial transformer feeders
  • Outdoor secondary substations

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FAQ

Frequently asked questions

What do standard Ring Main Units do?

Standard RMUs provide load-break switching and short-circuit protection for distribution transformers in MV ring networks. They are typically used at secondary distribution points, feeding a single transformer or short cable spur.

What are the maximum ratings of these RMUs?

They are rated up to 24 kV and 630 A, with standard 1, 2, 3, or 4-function configurations.

What insulation options are offered?

Options include a sealed-for-life SF6 tank or air-insulated construction. Schneider Electric's RM6 is gas-insulated and SM6 is air-insulated.

Can the RMUs be operated remotely?

Yes. Optional remote control and motorisation are available, and the compact footprint suits tight substations.

Where are standard RMUs typically applied?

Typical applications include compound and residential MV networks, commercial building distribution, industrial transformer feeders, and outdoor secondary substations.

How do I choose the number of functions for an RMU?

The standard 1, 2, 3, or 4-function configurations are selected from the network layout: incoming and outgoing ring cables use switch functions, while each transformer feeder uses a protected function. Our engineers can advise on the right configuration for your scheme.

Which standards apply to NLC's Ring Main Units?

As authorised Schneider Electric assemblies, the RM6, SM6, and FBX ranges are built to international IEC standards for MV switchgear, with sealed-for-life tank construction and standard fault-make and load-break ratings.

Is installation and after-sales support available?

Yes. NLC supports the RMU from configuration and supply through to installation guidance and after-sales service, with motorisation and remote control options for network automation.