Defence Aircraft Ground Power
THYCON was engaged to refurbish the 400Hz Ground Power Supplies used for the maintenance of fighter aircraft at RAAF Williamtown.
Centralised Thycon 400Hz 960V SFX systems were supplied with power reticulated to a number of 50kVA 960/200V step down isolation transformers at various locations around the hangar.
The 960V 400Hz supply is earth referenced allowing standard earth leakage protection to be used addressing health and safety concerns raised by personnel working on the floating reticulation systems. At the same time the low voltage output of each transformer was left floating to meet aircraft requirements.
A 960V reticulation scheme was chosen to minimise voltage regulation issues and cable size between each Thycon 400Hz SFC and the various isolation transformers.
Cabling into and out of each cabinet was achieved using a plug & socket arrangement. This allows for the easy removal and reinstatement of the equipment during the site’s regular fire suppression tests. Providing a plug on both ends of the aircraft umbilical also provided a clear point of demarcation between RAAF and Base Facility Maintenance personnel.
Protective circuits were installed to ensure that the sockets could not become energised without a plug being inserted. This included the use of specialised micro-switches within each aircraft plug.
Each transformer was designed for air natural operation and was supplied inside a sealed stainless steel enclosure. Previous electrical installations had suffered severe corrosion due to salt air and aircraft fumes.
On each transformer cabinet external controls provides the user with basic power connect / disconnect functionality, as well as an earth leakage alarm and test facility. Cabling into and out of each cabinet was achieved using a plug & socket arrangement. This allows for the easy removal and reinstatement of the equipment during the site’s routine fire suppression test.
The SFC units themselves were installed outside of the hangar in a separate, lockable room. A 400Hz distribution cabinet was provided inside each hangar. The cabinet included remote control and monitoring of each SFC unit.