ESB Networks doubles Drumline 110 kV substation capacity to 20 MVA

The uprating of Drumline 110 kV station near Shannon illustrates the ongoing engineering focus across distribution grids to unlock firm network capacity through targeted brownfield plant replacement. By replacing two legacy 5 MVA transformers with new 10 MVA units, the utility has doubled installed substation capacity to 20 MVA while maintaining the existing site boundaries.

Upgrading transformation assets within an active 110 kV node presents distinct operational demands compared with greenfield developments. Station engineers had to stage the works across multiple phases, commissioning the initial 10 MVA transformer in March 2026 and bringing the second unit on stream in July 2026. Phased commissioning ensures that local industrial and residential feeders maintain supply continuity during civil modifications, busbar tie-ins, and switchgear adjustments. Uprating within established footprints avoids the protracted permitting cycles, land acquisition hurdles, and planning delays associated with constructing entirely new substations.

For distribution network operators, transformer uprating projects highlight the balance between asset lifecycle management and escalating demand. Adding 10 MVA of firm capacity provides immediate relief for regional circuits that face growing demands from electrification, commercial development, and distributed power generation. Moving from 5 MVA to 10 MVA specifications also allows network planners to standardise ratings across the 110 kV distribution fleet, reducing spares variety and streamlining long-term maintenance protocols.

Executing such upgrades on energized sites also brings critical interface challenges. Crews must manage tight clearances, temporary protection arrangements, and containment bund modifications to support heavier, higher-capacity oil-filled units. Managing the sequential removal, transport, and installation of power transformers within constrained yards demands precise staging to protect system reliability and avoid unplanned circuit tripping.

What this means for asset owners in the UK and Ireland: In Ireland, distribution system operators face rising load growth that demands careful staging during brownfield transformer replacements. Managing phased outages between March and July 2026 demonstrates the discipline needed to maintain system security while civil structures and bunds are reconfigured. Asset owners must align their transformer replacement schedules with extended factory lead times and establish contingency backfeeding plans to limit customer outage risk during on-site changeovers.