Our assets include transmission lines, high voltage underground cables, substations, switching stations, and digital infrastructure. Together, these assets form part of our high voltage transmission network that transfers electricity to more than three million households and businesses across NSW and the ACT.

Transmission lines and high voltage underground cables

A transmission line transmits electricity across vast distances.

It consists of a structure supporting conductors in the air, which are located at a safe distance from the ground. The structures are either steel towers or poles made of steel, concrete or wood.

Each conductor is connected to a string of insulators that either suspend or terminate the conductor at the structure. The insulators provide the required insulation to stop electricity leaking into the structure and then onto the ground.

Electricity is also transmitted into areas with high population density through high voltage underground cables.  This ensures electricity is safely and reliably transmitted to major urban areas.

Substations and switching stations

Transmission lines transport electricity at high voltages – primarily to minimise energy losses.

Before entering the distribution network managed by Ausgrid, Endeavour Energy and Essential Energy, the voltage must be reduced from 132 kV, 220 kV, 330 kV or 500 kV to lower voltages.

The change in voltages occurs at substations. A power transformer is used to change the higher voltage to lower voltage.  

Switching stations are used to provide greater control of the electricity at particular points in the network. The key difference between a switching station and substation is that a power transformer is not installed at the switching station.

Digital infrastructure

Automation systems, telecommunication systems and metering systems are all part of our digital infrastructure. They help us to ensure electricity is reliably transmitted across NSW and the ACT, and allow us to immediately respond to faulty transmission lines, substations and/or switching stations.  

Automation systems enable us to exert control in any part of the network and to enable communication between substations or switching stations and our control centre.

Metering systems located at customer connection points in the network, usually at substations, record the amount of power being transmitted at that point and charge the customer accordingly.