Gold Coast airport recloser upgrade

Gold Coast Airport (GCAPL), a dynamic, growing business, has experienced a 16% average annual growth rate in passenger movements over the past five years, resulting in greater energy consumption by the airport and its associated infrastructure nearby. The airport was serviced by an 11 kV feeder shared with several other customers. The electrical utility Energex recently commenced installing a new feeder for the airport to cater for its 'always-on-line' energy requirements.

A challenge in maintaining constant electrical supply to the airport was its existing oil-filled feeder recloser, which was beginning to show its age. While the unit was upgradeable, parts were becoming increasingly difficult to obtain and lockouts due to higher loads and faults forced the need to consider a more flexible and reliable option.

"Our main concern was improving the current rating over the old unit, but other features like automatically clearing transient faults, data logging and reporting were important considerations too," said GCAPL asset services manager, Geoff Arnold. "In fact, the unit we chose will service us past our current planned infrastructure upgrades "” something we didn't expect."

Shane Gorman, Noja Power sales engineer and project coordinator, explains that Noja Power was initially approached to just supply a recloser and control cubicle, but it was quickly decided to have them care for the whole project: "The airport is very busy, so taking power off-line was never an option. GCAPL wanted a complete package "” an integrated solution supported locally with training, fast response and spares availability.

"Because of our expertise and previous experience in this field, GCAPL asked if we could completely install the recloser system for them. So we managed the whole project: supplying the new recloser, providing the grading to coordinate with the Energex system, live-line installation, testing, commissioning and training. It included management software that provides statistical load monitoring to help GCAPL profile their current electrical needs and into the future. We also provide ongoing refresher training for their electrical staff, since the unit requires very infrequent attention."

Located close to the ocean, GCAPL wanted a system that was suitable for harsh conditions along with low environmental-impact potential. Using 'solid dielectric vacuum interrupting' technology, the Noja Power OSM recloser achieved GCAPL's requirements for low environmental impact by eliminating the use of oil and negating concerns over associated risks and safety concerns. The tank and control cubicle are manufactured using high-grade stainless steel, with the bushings 'high-pollution' rated to withstand salt-laden coastal conditions.

Other recloser types were considered, but rejected because their SF6 gas-insulation technology carries environmental concerns, with the Kyoto protocol listing SF6 gas for significant reductions.

To avoid disruption to the airport's internal power network, the old recloser was removed and the new unit installed using live-line techniques, maintaining the 11 kV supply throughout the installation, which took just eight hours. Protection settings for the new recloser were created from scratch and loaded beforehand to save time on site.

Noja Power assisted with grading the feeder to ensure the reliability and safety of the medium-voltage assets at the airport. Correct grading kept the supply balanced to avoid nuisance tripping while still providing adequate protection sensitivity.

"If the feeder isn't graded properly, there's the risk that a local fault at the airport, like birds flying into the overhead lines, could interrupt all customers along the entire feeder", explains Gorman. "Designing the recloser to trip approximately 400 milliseconds before the substation breaker trips means the recloser is coordinated with the substation breaker and automatically closes again after a short break to restore supply. So transient faults have very little impact to airport supply, but permanent faults cause the recloser to trip again and 'lockout' to protect assets downstream. All this happens automatically without human intervention, providing the right balance between nuisance tripping and a safe electrical supply."

Noja Power worked with Energex to coordinate the settings of the new 11 kV feeder and mirror them at the new recloser, with only slight modifications to optimise performance, while anticipating the future needs and characteristics of the new feeder.

"It was a complete package," announced Arnold. "Noja Power manufactured and supplied the equipment, engineered the protection settings, coordinated the installation and provided training for our engineers. We're very satisfied with the result."