Contracting Capabilities

Northpower provides contracting services across the North Island including engineering, infrastructure management and maintenance and construction.

Big Omaha Substation Construction

Location: Big Omaha, north of Warkworth

Start date: 27 May 2022

Completion date: 12 September 2023

Key people involved: Rroy Sison, Ben Cutforth, Shaun Du Piesanie, Donovan Du Piesanie, Ale Amosa, Lindon Connolly, Andreas Eleftheriadis

Project partners: Vector Ltd, Cassidy Construction

Our Challenge

Construction of a new substation for our customer Vector at Big Omaha, north of Warkworth, was undertaken by Northpower’s contracting team to address voltage issues experienced under normal and peak load conditions.

With a rapidly increasing local population, voltage modelling in the area indicated low voltage under normal conditions at peak load and very low voltage under backstop conditions. By installing a 33/11kV transformer, supplied from Vector’s Warkworth substation, the new Big Omaha substation now addresses these voltage issues, with provision for a second transformer in the future also accounted for in the project design.

What was involved

  • A staged approach, with installation of an initial single 15 MVA transformer, followed by the installation of a 33/11kV transformer
  • Installation of a container switchroom and switchgear
  • Infrastructure development including firewall, fencing, landscaping, pole replacement, and HV cable installation
  • Connection to Vector’s Warkworth substation for power supply.

Improving reliability

Ensuring the operational continuity of the existing Warkworth substation while undertaking construction activities at Big Omaha required detailed planning and project execution, with adverse weather conditions also creating additional challenges for the project team.

The project benefited from great teamwork and commitment from all stakeholders involved, including our Auckland Zone Substation team and other project contributors. The project was successfully delivered in September 2023 and represents a significant infrastructure development aimed at improving voltage stability in the Omaha region.

The substation is supplied from Warkworth’s 33kV overhead line, ensuring optimal voltage levels. In case of transformer failure, the substation will be supplied from Warkworth at 11kV via the same overhead line, with appropriate operation and switching of ring main units (RMUs) at Warkworth and Big Omaha.

The project is expected to successfully address voltage issues and contribute to the overall reliability of electricity supply  in this growing area.