Electrical System Flashcards
normal operation mode
split parallel
other modes of operation
parallel and isolated
What is parallel mode?
all IDGs connected with AC and DC cross ties tied
What is isolated mode?
if you open the bus ties on each half and all IDGs will be isolated
6 emergency buses
AC/DC emergency buses
AC/DC transfer buses
battery bus
battery direct bus
What will power the emergency AC bus?
gen bus 2 normally
gen bus 3 back-up
if neither of those can, then batteries will through the inverter
How long are aircraft batteries good for?
as long as 30 min if XFER buses are off within 15 min
What is the purpose of the transfer bus?
it allows the maintaining of minimum essential loads while shedding loads of other buses not essential for safety of flight during Electrical Smoke and Fire Procedures
What are the AC and DC transfer buses normally fed from?
the #3 AC and DC avionics buses
What happens when the transfer bus switch is in the OFF position?
all power is removed from the AC and DC transfer buses
What happens when the transfer bus switch is in the NORM position and avionics bus 3 power is lost?
the respective emergency bus is the source of power for the AC/DC Transfer bus
What does a DC XFER BUS OFF amber light on the ESCP indicate?
a loss of power for only the DC Transfer bus
How would you know if you have a loss of AC Transfer bus power?
annunciated on the WAP with an AC XFER BUS message
What is the priority of the gen buses if only one engine generator is working?
for any given generator operating, it will power gen bus 2 (as this normally powers the emergency buses) and it’s respective gen bus
gen bus priority
2, 3, 1, 4
