Flashcards in Electrical Questions Deck (35):
How many networks make up the electrical system on the airplane? why?
2 independent networks
Redundancy and fault isolation
What happens if a power generating source fails?
Bus ties automatically connect to provide no system degradation
What components powers the AC system?
1) 2 IDGs
4) Ram Air Turbine (RAT)
5) AC GPU receptacle
What components power the DC system?
1) 2 NiCad Batteries
2) 3 TRU's
3) 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 IDGs?
Each has a Generator Control UNit (GCU)
Can one IDG supply the entire electrical system?
What will cause the amber IDG on the overhead panel to illuminate?
High Oil Temp
Low Oil Pressure
If an IDG is manually disconnected, can the flight crew reconnect it?
No. MX function on the ground
What is the primary purpose of the AC Generators?
To power the AC busses and the AC ESS BUS which...
Power the 3 TRU's, 1,2, and ESS
what is the purpose of the TRU's?
To convert 115VAC to 28 VDC
Can the APU replace a failed IDG?
Yes up to 33,000ft
What is the AC electrical systems priority?
Cross side (other IDG)
***the airplane uses an onboard AC power source beofre an external AC source
How is it known that an AC GPU is hooked up to the airplane and ready to provide electricity?
-GPU button displays AVAIL and the GPU icon is presented on the electrical Syn 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 Bus is In Use
-Cockpit GPU button will display AVAIL even though the ground service bus is in use
If the airplane is using the AC GPU and the APU is started, what should the pilot be sure to do?
Deselect the GPU button
What will charge the batteries?
Any AC Power source
How long will the aircrafts batteries last with no recharging?
What is the purpose of the DC GPU receptacle?
For APU start when batteries
What is the Min battery temp for APU start?
What is the Minimum battery voltage to close the battery bus ties?
What battery is used for the APU start?
-BATT 2 powers the APU Start Bus
-BATT 1 powers the FADEC & EICAS for monitoring
What is the purpose for the inverter?
Converts 28 VDC from the batteries to 115 VAC to power the AC STANDBY BUS whan an AC souce is not available
What is on the AC STANDBY BUS?
Engine Igniters 1A and 2A
What powers the Ram Air Turbine (RAT)?
Airflow turns the RAT prop which spins the turbine inside
When will the RAT deploy?
-Automatically deploys if AC BUSSES are not powered
-Manually by the pilot
How long after deployment before the RAT will supply power?
Is there is a total loss of power during the 8 second RAT deployment?
No. Batteries supply power to the DC ESS BUSSES and AC STANDBY BUS
What does the RAT power?
What is the Min airspeed for the RAT?
-Load shedding occurs below this speed
When is the RAT icon displayed on the Electrical Syn Page?
When the RAT is deployed
What manages the electrical system?
-4 Integrated Control Centers (ICC)
-2 Secondary Power Distribution Assemblies (SPDA)
What is an ICC?
An Electrical Control device, which provides power distribution and protection for electrical loads
What is a SPDA?
An electrical load management unit (powered by the ICC's) that distributes electrical loads to aircraft systems according to distribution logic