@ z.khalid
What do you mean with "all the hydraulics are electrically controlled"?
As i said: the hydraulic sorce (EDP) control itself mechanically.
By switching the EDP to OFF you energize a depressurizing valve via a solenoid and the fluid output goes to zero. If you now lost the electric for this solenoid (DC BUS 1 for the ENG #1 and DC BUS 2 for ENG #2) the EDP start to supply the system again (Failsafe). Or in other words: losing your DC BUS does not mean that you lose your hydraulic source.
BTW: DC BUS 1+2 are not supplied by the emergency generator.