Technical Overview

Horizon Energy's network distribution assets transport and distribute electricity to end use customers.

Horizon Energy owns, manages and operates a distribution network in the Eastern Bay of Plenty covering an area of approximately 8,400 km2. The number of consumers served by the network is approximately 23,000 with a maximum demand of 90 MW.

Horizon Energy's distribution assets were last revalued at 31 March 2004 with a depreciated replacement cost (DRC) of $74.2m. At 31 March 2005 the DRC had increased to $76m.

Horizon Energy takes supply from Transpower at four grid exit points: Edgecumbe, Kawerau, Waiotahi and Te Kaha. Supply from Edgecumbe is at 33kV and is distributed to Horizon Energy owned 33/11kV substations.

At the other Transpower grid connection locations supply is taken at 11kV to feed directly into Horizon Energy's distribution network.

Assets

• 33kV, 11kV and 400V lines and cables
• Zone substation assets including transformers and switchgear
• Distribution substation assets including distribution transformers
• Distribution switchgear
• Ripple injection load control plant
• Other system fixed assets (SCADA, communication systems)

Customer Service

We pride ourselves on high levels of service based on customer expectations, regulatory requirements and strategic and corporate goals. Agreed performance measures enable customers to rate our systems against the criteria of safety, quality, environmental standards, reliability, efficiency/pricing and responsiveness.

Operations

Horizon Energy has an operations group employing appropriate systems for network operation and control. Our control centre is located within our main office in Whakatane and is staffed nine hours per day excluding weekends and public holidays. Outside these hours, selected engineering staff undertake operational control using remote on-line access to the Supervisory Control and Data Acquisition (SCADA) system.

The control centre has a real-time SCADA master station system and remote terminal units are installed at every zone substation for local control and data capture.

Load control systems give us the ability to shift approximately 10MW of load during the peak period. Load control policies are agreed with energy retailers operating on the network.

Reliability Enhancement

Measures have been initiated to improve reliability and the quality of supply on the network within the framework of that required by customers. There has been significant improvement achieved over the last few years, although there is some concern at the trends adverse weather events have caused.

Some of the improvement has occurred as a result of the application of new technologies such as a new SCADA system; minimum maintenance circuit breakers; electronic relays; remote controlled line switches; auto-reclose circuit breakers; remote controlled circuit breakers; and General Distribution Automation.

The average number of minutes a customer's service is interrupted has shown a significant decline over the years. The impact of the extreme weather events is evident in 2004 and 2005.