Electricity Transmission and distribution

Queensland’s resources sector consumers require energy for the operation of mines, mineral processors such as smelters, crushers and refineries, gas and chemical manufacturing and supporting export infrastructure such as ports and rail.

The electricity supply industry in Queensland comprises a number of interconnected sectors:

  • Generation: Electricity is produced at power stations (generators) or large scale renewable plants.
  • Transmission: Electricity is transported from power stations through the high voltage transmission network. Voltage is then reduced to a lower voltage at substations.
  • Distribution: Electricity is distributed to homes and business via ‘bulk supply’ substations.
  • Retail: Electricity is sold to customers by an electricity retailer.

The electricity supply transmission and distribution industry conveys electricity from the generating power stations to the consumer by means of a reticulation system that includes the following component sections:

  • Conductors and poles distribution. This is usually reticulated in built up areas in both industrial/commercial and residential settings or rural settings,
  • Underground cables distribution. Where installation and cable jointing are specific skills. This is usually reticulated in built up areas in both industrial/commercial and residential settings,
  • Overhead conductors distribution. Suspended from towers (or larger concrete or wooden poles) at voltages substantially higher than those used for distribution,
  • Underground cable transmission.  Which are usually oil or gas filled requiring special skills in installation and maintenance.

Electricity Transmission:

Electricity transmission is the bulk movement of electrical energy from a generating site, such as a power plant, to an electrical substation. The interconnected lines which facilitate this movement are known as a transmission network. This is distinct from the local wiring between high-voltage substations and customers, which is typically referred to as electric power distribution. The combined transmission and distribution network is known as the “grid”.

Powerlink Queensland, a Government Owned Corporation, is responsible for planning, developing, operating and maintaining the high voltage electricity transmission network in Queensland. Powerlink operates more than 12,000 kilometres of Queensland’s high voltage transmission network, transporting electricity from the generators to the distribution networks and directly to large customers such as aluminium smelters.

Electricity Distribution:

Electricity distribution is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers. Distribution substations connect to the transmission system and lower the transmission voltage with the use of transformers. Primary distribution lines carry this medium voltage power to distribution transformers located near the customer’s premises.

21 June 2011 Townsville, Queensland - Ergon Energy apprentices - Photo: Cameron Laird (Ph: 0418 238811)

Distribution transformers again lower the voltage to the utilisation voltage of household appliances and typically feed several customers through secondary distribution lines at this voltage. Commercial and residential customers are connected to the secondary distribution lines through service drops. Customers demanding a much larger amount of power may be connected directly to the primary distribution level or the sub-transmission level.

Electricity in Queensland is supplied to most customers via an electricity distribution system, which connects the high voltage transmission system to individual premises.

Queensland’s industrial, commercial and domestic consumers of electricity are serviced by the following electricity distribution companies:

  • Energy Queensland, comprising of:
    • Energex – who supplies customers in south-east Queensland
    • Ergon Energy – who supplies customers in rural and regional Queensland
  • Country Energy – a NSW distributor whose supply area extends over the border.

QWSS-RailRail Traction:

The distribution of electricity used for transporting of people and goods by various types of rail traction vehicles (e.g. tram and train) involves the carrying out of construction, maintenance and inspection of overhead traction wiring systems and
equipment in accordance with legislative rules and regulations.

Cable Jointing:

Work in the area of cable jointing involves the laying, installation, jointing and maintenance of de-energised LV and HV underground polymeric cables and the installation and maintenance of electrical equipment. Options are available for skills to be obtained for energised cables and or Low and High Voltage paper insulated cables.