The action you need to take for Loss of Mains Settings

Energy Networks Association have brought forward plans to force all installations to change their Loss of Mains (LoM) settings following a recent national power outage that caused travel chaos.

Generation owners are required, by the Distribution Code, to install Loss of Mains (LoM) protection at their distributed generation sites. This is to ensure that distributed generation does not form an autonomous power island with the remaining local demand. Other faults elsewhere on the GB electricity system should not result in the operation of LoM protection.

In most cases, LoM protection is provided by means of a protection relay. However, some sites may have LoM functionality built in within the generation control system, e.g. within individual inverters.

It was identified that loss of mains protection with these settings could inadvertently operate and trip your site, following events that do not result in islanding. Not only would this result in some loss of revenue at each site that has been unnecessarily disconnected from the system, but also the total generation loss at multiple sites. This could cause a significant system disturbance and a widespread loss of supply.

In some cases, a site might comprise multiple inverters. In such cases, all inverters must be modified if this is necessary to conform to the new requirements. If these protection devices cannot be reset appropriately and are used to provide LoM protection for other types of generation, they must have the LoM function disabled.

The ALoMCP programme does not cover any replacement to an inverter itself, as the work will need to be done through changing the logic of their control system (either resetting them or disabling the LoM function).

If resetting the logic of the control system is not possible, the implications will need to be discussed with the DNO and may result in adding a mains protection relay to the system. Power Different will discuss this with the DNO and quote after the site evaluation & DNO consultation.

Owners of generation have a requirement to comply with the modified interface protection requirements in the revised EREC G59 and have until 31 August 2022 to do so. After that date owners who have not made the change may be the subject of an enforcement programme.