RMU (Ring Main Unit)
A compact medium-voltage switchgear assembly used to connect, isolate, and protect individual equipment stations (such as PCS and transformer skids) on a BESS site. Each RMU typically contains load-break switches and a fused or circuit-breaker-protected feeder, allowing a single station to be de-energised without affecting the rest of the MV ring.
In energy storage
On a typical utility-scale BESS site, each PCS-transformer station connects to the MV ring via its own RMU, allowing any single station to be isolated for maintenance without de-energising the rest of the plant. The ring topology also provides redundant supply paths — if one section of cable is faulted, the ring can be reconfigured to maintain supply to the remaining stations.