Decision on causer of 26 July 2024 under-frequency event

Following consultation, we have determined that Transpower New Zealand Limited, as grid owner, was the causer of the 26 July 2024 under-frequency event.

An under-frequency event occurred at 7.21am when frequency dropped to 49.14Hz in the South Island. An under-frequency event occurs when the system frequency falls below 49.25Hz because of a loss of injection of more than 60 megawatts into the grid.

The Authority did not receive any feedback that disputed its draft determination.

In accordance with clause 8.65 of the Electricity Industry Participant Code 2010, the clearing manager will rebate the event charges to the relevant participants. The event charge calculated in the system operator’s report to the Authority is $213,750.

Any dispute of this final determination can be lodged with the Rulings Panel by 5pm on 22 September 2025.

About under-frequency event determinations