ELEC NON NORMALS Flashcards
Back up power
Provided by back up gens
Ensures power for essential loads
Essential loads powered by the left and right transfer buses
Essential loads
Instruments and panel lighting
Capt and fos radios
Left and and centre pitot and engine probe heat
Transfer buses powered by
Left and right main AC buses
Back up gen switches
When on allow the transfer buses to switch to the back up gens automatically
Back up gen lights
Remain off light until associated engine is running
Backup power system provides power
Uninterrupted transfer of power to essential loads when Loss of one main bus Loss of both main AC busses Only one main gen available Auto land
If you lose all gens and back up gens
Standby system will power
Critical AC loads Centre ILS RA Marker beacon left ATC transponder left vOR left Engine igniters
Critical Dc loads
Captains and FOS flight instruments and displays
Should the transfer buses become unpowered
RAT provides DC power through the TRUs and the standby AC bus is powered from the battery bus through a standby inverter
RAT
Provides continuous hydraulic and electrical back up power
Output less than one tenth of the other generators
Deployed automatically when
Both transfer buses are unpowered
All three hydraulic system pressures are low
Dual engine failure and centre hydraulic pressure low
RAT pressure light
Illuminates when it is producing a minimum of 1500 psi for the flight controls
RAT vs Battery standby power
RAT will power both captains and fos flight instrument busses
If only standby battery captains will only be powered
Drive light in flight
Low IDG oil pressure
Or
High IDG temp
Will auto disconnect drive generator
Power of transfer busses
Can only be performed by one backup gen at a time
