GSR038 - Single Transformer Offshore AC Substations | National Energy System Operator
Summary
Code modification GSR038 proposed to remove the requirement for two offshore AC transformers at grid entry points of 90MW or more has been withdrawn. The modification aimed to assess restrictions in Grid Code Clause 7.7.1.1 that effectively mandated dual transformer configurations. NESO classified it as having high impact on offshore transmission owners and generators.
Why it matters
The withdrawal suggests that cost savings from single transformer configurations could not overcome reliability concerns or technical constraints. Offshore developers remain bound by existing dual transformer requirements, maintaining higher capital costs but preserving system resilience.
Key facts
- •Grid Code Clause 7.7.1.1 requires dual transformers for capacities ≥90MW
- •Modification withdrawn on 26 March 2026
- •High impact classification for OFTOs and offshore generators
Areas affected
Related programmes
Memo
GSR038 - Single Transformer Offshore AC Substations | National Energy System Operator Show/Hide Menu Toggle Add to favourites Close tooltip Sign in to add this page to your favourites Sign in or register Show favourites Close Close tooltip Sign in or register to manage your favourites Sign in or register Help You are now signed in Visit My NESO account to view and manage your dataset subscriptions. Maybe later Go to your account GSR038 - Single Transformer Offshore AC Substations This modification is proposed to assess the restriction in Clause 7.7.1.1 that effectively requires two offshore AC transformers for grid entry point capacities of 90 MW or more. Modification status: Withdrawn - Concluded Last updated: 26 March 2026 Code administration contact: [email protected] This modification is expected to have a: High impact on Offshore Transmission Owners (OFTOs) and Offshore Generators and a Medium impact on NESO Governance Route: Standard Governance modification to proceed to Code Administrator Consultation Code modification proposed by: Slawomir Kurek [email protected] Documents Proposal Document Terms of Reference Workgroup Meetings and Summary Papers Workgroup Consultation Workgroup Report Code Administrator Consultation Draft / Final Modification Report Decision Name GSR038 Proposal and Annexes GSR038 Proposal logo--facebook