Power was cut to large areas of the North Island on Tuesday 13th December 2011 by a fault at the 1448 MW Huntly power station. While the cause of the problem is not known (at the time of this news item) its effect was widely felt by power being suddenly disconnected to more than 200,000 consumers in areas from Wellington to Auckland and further north. The incident triggered load shedding to retain the balance between generation and demand and to protect the national grid from collapse.

Quasar’s FCAS application is installed at numerous locations around NZ and captured the 47.6Hz event. The resulting information shows the grid frequency immediately prior to the event and for the period following. This post period shows the connected generation’s response to the event as it begins to recover the frequency to 50Hz.