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.