The Accelerated Loss of Mains Change Programme (ALoMCP) has been rolled out by National Grid ESO and the UK DNOs (Distribution Network Operators) and iDNOs (independent Distribution Network Operators) to accelerate compliance with the Distribution Code.

The purpose of the initiative is to consider Accelerated Loss of Mains Change Programme (ALoMCP) protection and their settings. The aim being to reduce the risk of inadvertent tripping and reduce system balancing issues by giving National Grid ESO greater latitude with regards to system RoCoF limits.

Your generator will have been connected to the Distribution Network under technical standards that require it to be tripped off at times of network disturbances. This is commonly referred to as the “G59 trip” or “G59 relay”, as G59 was the number of the Energy Networks Association Engineering Recommendation adopted by all DNOs/iDNOs. When your generator was commissioned, the G59 relay would have been programmed with the settings prescribed at the time, then tested and possibly witnessed by the DNO/iDNO.

As more and more distributed generation as been connected to the grid, concerns increase about the amount of generation that can be lost during a system disturbance, due to the G59 relays doing what they were programmed to do. As well as that, nationwide experience has shown that Vector Shift loss of mains protection has not provided results as predictable as had been hoped for.

The ALoMCP programme aims to reduce the likelihood of large amounts of distributed generation being lost on system disturbance by making changes to settings in G59 relays to reduce the sensitivity to tripping, and to migrate any relays still using Vector Shift onto Rate of Change of Frequency (ROCOF).

The Energy Networks Association has published a webpage HERE to provide more information.