Sovereign Electrical System Flashcards
What is a SPLIT Bus system?
Left and Right Electrical Buses are isolated from one another
What does the GCU do?
- Regulates voltage to 28.5 V
- Protects
U-R Under-voltage or Reverse Current Opens GEN relay
O-F-F Over-voltage, Feeder Fault or Fire Button Opens Field relay
How long will the batteries power the entire electrical system?
20 minutes
How long will the batteries power the electrical system after Load Shedding (L ELECT and R ELECT Buttons to EMER)?
1 hour
What causes the AVAIL light to illuminate?
GPU output is between 26.5 and 32 volts
What does the BUS TIE relay do?
Allows the entire electrical system to be powered from 1 generator
How can you confirm the GPU is disconnected?
- AVAIL light extinguishes and
2. Visual conformation
What does the INTERIOR Button do?
NORM - Turns ON Cabin electrical power
OFF - Turns OFF all electrical power to the Cabin
What is on the Right CB Panel?
Respective Right:
Main DC Bus
EMER Bus
Avionics Bus
What is on the Left CB Panel that’s not on the right?
Standby Instrument Bus
What bus must be powered for Cabin Entry Lights?
Right Battery Bus
When will the EMER lights illuminate?
1. EMER lights switch ON With EMER lights switch in the ARM position: 2. PAX SAFETY ON 3. Loss of Main DC Bus power 4. 5 G impact
What causes a RED BATTERY O’TEMP CAS message?
> 63 degrees C and assuming the first activation was reset the warning will recur > 71 degrees C
What should you do if you get a BATTERY O’TEMP on the ground?
- Unload Battery(ies)
2. Call Maintenance
Where do the EMER Lights get there Power from?
4 NICAD battery packs located above the ceiling panels in the Cabin
How long will EMER Lights last?
- Indefinitely using Main DC Bus power
- 60 minutes using EMER Bus power
- 10 minutes using Battery Packs
With the AVAIL light illuminated what happens when the EXT PWR Button is pressed?
Connects the GPU to the right EMER Bus
When the APU READY TO LOAD light is illuminated what happens when the APU GEN Button is selected ON?
Connects the APU generator to the Left EMER Bus
What Bus is powered when a battery is connected?
Respective BATT BUS
What happens when either the Left or Right BATT Button is selected ON?
Respective BATT relay closes connecting the BATT BUS to it’s respective EMER BUS and via the BUS TIE relay powers the opposite EMER BUS
Explain the logic of the BUS TIE relay?
On the ground the BUS TIE will automatically OPEN or CLOSE based on single primary power source and Engine or APU Start logic. In flight the BUS TIE is manually actuated.
Note: In flight, if the BUS TIE has been manually CLOSED, the BUS TIE will automatically OPEN for an Over Current (>600 amps) condition
How does the Main DC Bus receive power?
From its respective EMER BUS via its ELEC relay
What is the NORMAL position of the ELECT relays?
Closed (could also be referred to as Load Shedding relays)
What items are on the Left BATT BUS?
- AFT BAGGAGE Lights
- TAIL CONE Lights
- APU Test Panel
- NWS Accumulator Bleed
- Battery Voltage
How many AMPS should the GPU be set to for Engine Start?
1000 to 1500 amps
What is on the Right BATT BUS?
- Cabin Entry Lights
- Under Pylon Lights
- LAV Service
- ELT Panel
- Battery Voltage
Which Buses do the BUS TIE relay connect?
Left and Right EMER BUS
What happens to the APU generator when the Left Engine Generator comes on-line and why?
APU relay opens, because of priority logic and only 1 power source on that sides Bus at a time.
What monitors the Electrical System?
MAU’s
What does a DC-DC Convertor do?
Maintains 24 Volts minimum during Engine Start
What powers EICAS?
Right EMER BUS
When does the BUS TIE close automatically?
On the ground ONLY:
- When the Engine or APU start Button is pressed
- Whenever a Single Primary Power Source is selected