Electrical Flashcards
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation.
How many networks make up the electrical system on the airplane? Why?
I. 2 independent networks
II. Redundancy and fault isolation
What components power the AC system?
2 Integrated Drive Generators (IDG) Auxiliary Power Unit (APU) Inverter Ram Air Turbine (RAT) AC GPU receptacle
What components power in DC system?
2 NiCad batteries
3 Transformer Rectifier Units (TRU)
DC GPU Receptacle
How does the IDG maintain a stable power output?
A Constant Speed Drive (CSD) attaches the IDG to the AGB (Accessory Gear Box)
What monitors and controls the IDG’s?
Each has a Generator Control Unit (GCU)
Can one IDG supply the entire electrical system?
Yes
What will cause the amber IDG light on the overhead panel to illuminate?
Hi oil temperature
Low oil pressure
If an IDG manually disconnected, can it be reconnected by the flightcrew?
No. This is a maintenance function
What is the primary purpose of the AC generators?
To power the AC BUSES and AC ESS BUS which…
Power the three Transformer Rectifier Unit (TRU) One, Two, and ESS
What is the purpose of the Transformer Rectifier Units?
To convert 115V 400Hz AC to 28V 300 Amp DC
Can the APU replace the failed IDG?
Yes (below 33,000ft)
What is normal AC electrical priority?
Onside (IDG)
Inside (APU)
Outside (GPU)
Cross-side (other IDG)
Note: The airplane uses an onboard AC power source before an external AC source.
How is it known that AC GPU is hooked up to the airplane and ready to provide electrical power?
GPU button displays AVAIL and the GPU icon is presented on the electrical synopsis page.
Once the GPU button is pushed in, the button will display IN USE provided another AC power source is not available.
What does it mean if the AC GPU is plugged in and the outside GPU panel button displays “IN USE”?
Ground service button is “IN USE”.
Cockpit GPU button will display “AVAIL” even though the ground service bus “IN USE”.