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Marine solution: The Ring Main Unit solution


Value proposition


Main drivers:

  • In the large market of containers and booming MV applications, shipbuilding companies are looking for innovative solutions so as to provide efficient ships and save on construction costs.


Solution in brief



  • The Ring Main Unit solution combines all MV functional units to enable connection, supply and protection of one or two transformers on an open ring network.


Value proposition

  • Opex reduction: length of HV cables reduced, shortening average ratio >30% for the configuration
  • Peace of mind: The new RM6 generation benefits from the accumulated experience acquired from the 850,000 functional units that equip electrical networks in more than 50 countries in America, Asia, Europe and Australia.
  • Improvement of network maintainability and availability :

  A failed cable section on the HV loop can be disconnected

  Automatic reconfiguration of the HV loop is possible after fault detection.


Differentiation factors:

  • Optimised main HV switchboard footprint
  • Reduction of losses
  • Easy feeder segregation
  • Choice of ‘‘all-in-one'' units integrated in a single metal enclosure,
  • Fast installation, fast cable connections on the front.





Main characteristics

Main characteristics

Why is the HV loop adapted to a ship?

A HV loop network is composed of several substations, called RMU (Ring Main Units). Each substation consists of several HV functions.

Two HV switch-disconnectors ensure the closing or opening of the HV loop.

One or more transformers can be protected through a circuit-breaker or a fuse switch combination.


The electrical architecture of a ship is divided into two parts:

  •  the machinery space composed of propulsion motors, thrusters, power generation, pumps... Generally, the associated electrical architecture is a radial configuration.
  •  the cargo, such as for example the accommodation part of a cruise liner. Several HV/LV transformers are dispatched in the different zones of the ship.


Therefore, a HV loop configuration is an adapted solution as the loads can be supplied as near as possible.






Success Stories

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