A330 AC EMERGENCY GENERATION
The AC emergency generation which consists of the Hydraulic Electrical Generating System (HEGS) enables to restore part of the distribution network in case of emergency configuration (loss of the two main busbars: AC 1 and AC 2).
The HEGS is composed of the following items:
- the hydraulic Constant Speed Motor (CSM),
- the AC generator,
- the Generator Control Unit (GCU).
The CSM and AC generator form an assembly called the Constant Speed Motor/Generator (CSM/G) 8XE.
In case of loss of the two main busbars AC 1 and AC 2, the CSM is supplied by the green hydraulic circuit which is powered:
- either by the green hydraulic engine driven pump(s) (one pump driven by engine and/or the other by engine 2) if one engine at least is operative,
- or by the Ram Air Turbine (RAT) pump in case of loss of both engines.
In case of loss of the AC main busbars, the CSM supplied by the hydraulic fluid drives the AC generator. The AC generator is controlled by the CSM/G GCU (1XE) and provides the AC power supply (115 VAC/400 Hz, 3 phases).
It supplies:
- the AC ESS buses (4XP, 9XP) through the EMER GLC (2XE),
- the DC ESS buses (4PP, 8PP) through the ESS TR.
The two main batteries supply the DC ESS BUS (4PP) and, via the static inverter, the AC ESS BUS (9XP) during the transfer to emergency generator operation after the loss of the main busbars.
The AC ESS SHED BUS (401XP) and the DC ESS SHED BUS (8PP) are shed respectively by the relay 16XH and the contactor 1PH when:
- the CSM/G is supplied by the RAT hydraulic pump and,
- in batteries only configuration.
So yes hydraulics can supply electrical AC power to power avionics bits and bobs.