Instantaneous reserve

Instantaneous reserve is generating capacity, or interruptible load, available to operate automatically in the event of a sudden failure of a large generating plant or the HVDC link.

This service is required to stop the resulting fall in frequency and allow the system frequency to recover promptly to 50 Hz.

We enter into instantaneous reserve contracts with participants who can offer instantaneous reserve compliant with our technical requirements and the Code.

Instantaneous reserve is procured on a half-hour clearing market basis.

Special Protection Systems


Special Protection Schemes are means by which circuit loadings, voltage or frequency can be controlled after an event on the power system which might otherwise cause an overload of transmission equipment (eg circuit or transformer).

The following is information that we have published on special protection schemes

Excursion Notices

Excursion notices are emailed out to registered electricity market participants and comprise of the following notice types and :

  • Frequency Excursion Notices
  • Voltage Excursion Notices

You can subscribe to this page.  Subscribe to this page to receive an email notification when a new Excursion Notice is published.


Find specialised information related to our regulatory control periods, generation connection, and more.

Site Star Rating App

You can participate in Transpower’s substation rating system by using the Site Star Rating App. Only a valid Transpower email address is needed to register. Registration and login is only required for the first time use, provided you only intend to use the App on one device at a time.

How demand response works

Demand response allows electricity consumers to reduce their electricity demand for a period of time in exchange for a payment.

Sometimes there are substantial, short-term increases in electricity demand. Changes like these may trigger the need for additional investment in New Zealand's electricity transmission network – a cost that is passed on to all New Zealanders.

Managing such peaks in demand can be an alternative to that investment, and we are testing the capability of the market to provide demand response as a way to carry out this management.