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Information for connected generators

If you own or operate a generator connected to the distribution network, you must confirm your equipment is compliant with the current technical rules, or make the necessary mandatory changes by 01 September 2022. If you do not make the necessary changes, you could be subject to enforcement action. The Accelerated Loss of Mains Change Programme is now closed to new funding applications. However all generation owners are still required to ensure that their equipment is compliant before 01 September 2022.

The Accelerated Loss of Mains Change Programme, known as ALoMCP, accepted funding applications from 19 September 2019 to 10 May 2022.  The ALoMCP provided payments to incentivise generation owners to make these important changes to their loss of mains (LoM) protection in advance of 01 September 2022 .

The changes need to be made by 01 September 2022, even if you haven’t applied to the programme for funding.  Any costs associated with the necessary changes must now be paid for by the person or organisation responsible for the generation.

Who is affected and what's happening?

All owner of non-domestic generation that was connected before 01 February 2018 need to confirm that their generation equipment is compliant with ENA EREC G59/3-7. Compliance will improve network resilience, and support wider initiatives helping meet the UK’s net zero targets.

All applicable generators will be required by the Distribution Code to have protection settings that are compliant with EREC G59/3-7 by 01 September 2022 or they could be the subject of an enforcement programme. Generation owners are encouraged to review their LoM protection settings now to ensure they are compliant before the deadline.

The requirements do not apply to domestic and similar generation that has been connected under EREC G83. It only applies to generation connected under EREC G59 before 01 February 2018, or in the case of type tested solar PV inverters, before 01 July 2018.

  • The technical section! What are the setting changes required in the updated EREC G59?

    All generators that are connected to the distribution networks in Great Britain have loss of mains (LoM) protection, one of the many protection requirements on the electricity system. This applies to generating plant within the scope of EREC G59, regardless of the type of generator eg PV, wind or gas etc. LoM is designed to check if a generator is still connected to the main network.

    The requirements of EREC G59/3-7 must be implemented by generation owners by 01 September 2022. Where LoM is provided by vector shift, it must be removed and/or replaced with rate of change of frequency protection (RoCoF). RoCoF is the rate at which frequency changes and is used to detect the absence of the connection to the system and disconnects the site if that RoCoF exceeds a specific value.

    The RoCoF setting requirement has been changed to 1 Hz/s with a definite time delay of 500 milliseconds. It will mean National Grid ESO will be able to operate the grid more efficiently.

    Most of the costs incurred in managing the LoM risk on the electricity transmission system is to limit the RoCoF to below 0.125Hz/s. Currently NGESO is limiting the RoCoF to below 0.125Hz/s so that generators with RoCoF protection are not inadvertently tripped. The costs are significant and are paid for by all of us through our electricity bills.

    These costs could be reduced if RoCoF above 0.125Hz/s was allowed. To achieve this, we need to change the RoCoF settings at all sites where RoCoF protection has an existing setting of 0.5Hz/s or less.

  • Who is involved in the Accelerated Loss of Mains Change Programme?

    The programme is a joint initiative with National Grid Electricity System Operator (ESO), the ENA, distribution network operators (DNOs) and independent distribution network operators (IDNOs).


  • The Programme Steering Group

    This group is the key forum for stakeholders to make sure their views are considered in the overall management of the Programme and reviews delivery by network licensees. It makes sure that the Programme is run efficiently and for the benefit of stakeholders and consumers.

    The Steering Group is comprised of representatives from network licensees including:

    • National Grid ESO
    • six GB distribution network operators
    • a representative for participating independent distribution network operators
    • up to three representatives of Balancing Services Use of System (BSUoS) charge payers
    • up to three representatives of distributed generation owners
    • an observer appointed by Ofgem

    Meeting minutes can be found on National Grid ESO’s programme document webpage.

  • Useful documents for applicants

    Retained for information only as the ALoMCP is closed for new funding applications

  • More useful information for applicants

    Owners can complete the settings changes themselves using their own contractors or site management teams. To assist, the ENA has a directory of contractors who claim they have the capabilities to undertake this work. Generation owners are entitled to use any competent contractor to make the changes to their assets.

    Contractors listed on the directory of contractors are self-declared as competent but are not officially registered or formally approved by DNOs or the ENA.

    A contractor does not have to be listed to participate in the Programme providing they can prove their competency to undertake the changes to the satisfaction of the generator.

    Individual DNOs also have list of contractors, published on their websites, which list contractors who have been active in those DNOs’ regions and have the capability to assess and make the necessary changes.

    For queries about your generation equipment, site, or compliance, please contact your local distribution network operator.