ELECTRICAL Flashcards
Will the OVRD switch
Batteries only
On ground
Connect shed buses?
No
AC system consists of:
- Inverter
Converts 28V DC to 115V AC
DC Bus1 - Inverter - 115 Vac Bus • EGPWS • Windshear • FOCWA • Printer • TCAS II (if installed)
What is EDL?
What does it control?
• Electrical Distribution Logic
Controls power contactors for:
• Fault protection
• Load shedding
• Electrical emergency opps.
What controls power contactors?
EDL
Electrical Distribution Logic
DC System consists of:
4 Engine Driven Gen’s (28V DC/400A)
1 APU Starter- Gen. (28V DC/400A)
2 Nickel-Cadmium Batt. (24V DC/ 44aph) 1 Lead-Acid Backup Batt. (24V DC/ 5aph) 1 GPU (28.5V 1600 amps)
GPU requirement volts and amps
28.5 volts 1600 amps
4 Gen ON
1 Gen OFF
2 Networks
All Buses
What happens when over current cond. exist or Bus fails?
EDL isolates the Bus
In the Air. Electrical Emergency
You have all screens ON.
What would you do?
Press Essential Power button….
That will connect batteries to ESS Buses
What powers Emergency Lights?
When will they come on automatically?
Powered by 4 batteries (22-24 hrs to charge them) Charged by ESS power. When switch in ARM lights will illuminate in electrical emergency. Otherwise controlled by CA of FA switches
3 Gen. ON
2 Gen. OFF
1 Network
All Busses
What converts
DC –> AC
Inverter
Why do we use Ni-Cad Batteries?
Discharge at the constant rate
Generators will come on line during start at…
% RPM N2
56.4%
If all generators fail ground? Air?
Electrical emergency
Batteries will supply system
Ground: 12 min. cuz they supply all buses
Air: 40 min. : Only essential buses are supplied, and central bus for APU start (3 attempts)
(Stb inst, Icas, RMU’s) - available instruments
2 Gen ON
3 Gen OFF
1 electrical network
NO SHED Buses
What buses power
• Taxi lights?
• Nose landing lights?
Shed buses
When (GPU Avail) but not selected
What Bus does it power?
And what’s on that Bus? (6)
(Ground Service Bus)
- PAX Cabin light
- Lavatory lights
- Galley lights
- Courtesy/ stairs lights
- Cockpit dome lights
- Baggage / service compartment lights
EDL and GCU (gen. control unit)
Is powered by?
Backup Hot Bus
⬇️
Backup battery (only powers Backup Hot Bus)
EFIS Power Source
PFD1 - DC1 MFD1 - DC2 ISIS - ESS2 ICAS - ESS1 MFD2 - DC1 PFD2 - DC2
RMU1 - ESS1
RMU2 - ESS2
TBSH - DC2
What generators charge the batteries?
Gen 1 and 3 charge Bat. 1 and
B/U Bat.
Gen 2 and 4 charge Bat 2
What happens in generator over-voltage situation?
GCU takes the Gen offline
Does the GPU. Have priority over Batteries and/or Generators?
YES, when selected
How long Photoluminescence Emergency lights last?
Initially 4.75hrs after a 15mim charge
