400 Hz cables are used for the power supply of aircraft, computer systems and radar stations.
The engines of aircraft are stopped while the aircraft are stationary, in order to save fuel as well as to decrease noise level and the quantity of exhaust gas at the airport . All international airports offer a 400 Hz supply voltage for stationary aircraft.
Due to safety reasons computer systems, radar equipment and communication systems of airports are connected to uninterruptable power supply plants via 400 Hz cables. With that, a total power failure is prevented, and frequency and voltage fluctuations are compensated. Nexans manufactures these interconnection cables for many different applications.
The 400 Hz network can be designed as a central, decentralized stationary or mobile system. The 400 Hz board supply requires cables and special plugs.
For distance up to 150 m a transmission voltage of 200/115 V is used. A higher voltage is chosen for larger plants with larger distances (600V up to 600m and 950V for more). For those plants a transformer is installed as near as possible to the aircraft (e.g at the end of the passager bridge) which reduces the supply voltage down to the board voltage of 200/115V.
All cables can also be supplied in a halogen-free RHEYHALON® design.
With 4 core cables voltage asymmetries and higher inductive voltage drops occur in 400 Hz networks when high ratings are transmitted. These unfavorable cable characteristics can be improved by using 7 core cables.
In those cables the centre core is used as earth or neutral conductor (green-yellow or blue), and six cores with the same cross section (black with white numbers) are laid in one layer round the centre core. Two opposite located cores are switched in parallel to one phase conductor.