NGESO issued a Capacity Market Margin Notice for the evening of 18 July at 19.00, and cancelled it an hour later.
The notice is a signal to the market that more generation is required to meet system requirements.
The automated notice, issued at 14.34, does not necessarily mean that supply does not equal demand – the capacity currently forecast on the transmission system at that time is 35,722MW, while demand (including operating margin) is predicted to be 35,228MW. But the operating margin is below a 500MW limit set by Capacity Market rules.
The market is expected to react to such notices by making capacity available.
Previously CM notices were posted by the system operator and cancelled shortly afterwards as new units were made available. One was posted on 24 January and cancelled at 14.00.
UPDATE The notice was cancelled at 15.04.

FURTHER UPDATE At 15.34 a new CM Margin Notice was issued for 20.00, because aggregate capacity of 35,592MW was available to meet transmission-connected demand of 35,140MW. The second notice was cancelled at 19.40.