@DearMRHazzard Auszug aus dem 777 *Electrical Systems":
The system on the Boeing 777 is configured with one IDG per engine, driven directly from the engine gearbox. There are two main electrical distribution buses, a left main bus and a right main bus, each normally supplied independently by their respective IDG. There is a third main alternator driven from an auxiliary gas turbine engine (called the auxiliary power unit or APU for short) located in the tail of the airplane, which is also rated at 120 kVA. Since the APU runs at a constant speed, this 24,000 rpm alternator is a direct drive, i.e., not an IDG. It is, however, essentially the same alternator used in the IDG. While the APU alternator is primarily a ground power source for the airplane, it can also be operated in flight to replace the loss of one engine driven IDG.
The 777 also incorporates a second power generation system, called the Backup System. This is a 25 kVA system intended to support essential services in the unlikely event of loss of all main alternators. A variable speed direct drive alternator was selected for this system to minimize the size of the engine installation. There is one backup alternator per engine directly driven from the engine gearbox at approximately 14,000 to 28,000 rpm. The output power of this alternator, at a frequency of 933 Hz to 1867 Hz, is converted to a constant 400 Hz by an electronic converter in the fuselage. Also incorporated within this machine are two permanent magnet alternators which are used as isolated independent supplies for the electronic flight controls system.
…und dann sind da noch die Pufferbatterien bevor RAT….
sag jetzt bitte nicht, aber atsb hat geschrieben….