POR-o definition
POR-o means the reduction in MW output (and/or increase in Demand) required at the Zenith Frequency, compared to the pre-incident output (or Demand), which is fully available and sustainable between 5 seconds and 15 seconds after the Event and where the zenith occurs between 5 and 15 seconds after the Event. If the actual Zenith Frequency occurs less than 5 seconds or more than 15 seconds after the Event, then for the purpose of POR-o monitoring the zenith is deemed to be the highest Frequency which did occur between 5 and 15 seconds after the Event.