Electrical Flashcards
What are the 4 potential AC power sources?
1.Two IDGs (Integrated Drive Generators)
2. APU
3. ADG (Air driven Generator)
4. External Power
What does a constant speed drive (CSD) do?
Allows IDG to spin at constant RPM which is better for electric as opposed to variable engine output.
How are the CSDs depicted on the Synoptic page?
IDG 1 / IDG 2
Can IDGs be reconnected inflight if failed?
No
Do pilots have control over DC ties?
No they are completely automatic
Which AC buses must have power for APU and Main battery charges to charge batteries?
Main battery must have AC Bus 1
APU must have AC service bus
What does the AVAIL switchlight mean on AC electrical panel?
AC EXT power is connected and compatible with the aircraft.
What is the difference between selecting AC external power on the electrical services panel and selecting it on the EXTERNAL services panel.
External panel only powers the service bus.
Inside all buses are powered.
What are the Volts and amp hours for the main battery? APU?
Main = 24V 17AMP DC Bat
APU = 24V 43 AMP DC Bat
What is the limitation regarding DC power only use on the ground? Why?
5 minutes. CRT screen cooling fans are AC power and they will overheat without them.
You walk into the cabin after the secure check and you notice that the emergency lights are on, what should you do?
Turn off then back to arm to reset the logic.
In flight how is the DC battery bus powered?
AC Bus 2 powers the ESS TRU 2.
What happens when you bring the battery master switch ON?
Connects BATT BUS to MAIN BATT DIR BUS and APU BAT DIR BUS.
(SYS 6-30)
What occurs when you select the DC service switch to on and from where will the DC service bus receive power?
Connects DC service bus directly to battery powered APU BATT DIR BUS
Receives power from TRU 2
(SYS 6-31)
What are the approximate voltage, phase and frequency of the AC power?
115V
3 Phase
400HZ
What is the GCU (Generator Control Unit) priority for AC BUS 1?
GEN1, APU GEN, GEN 2, External
AC ESS XFER switchlight has illuminated. What does this mean?
AC ESS BUS switched to getting power from BUS 1 to BUS 2.
What could cause the IDG to automatically disconnect?
Overtemp or overtorque
What would you see on the electrical panel as a result of TRU 1 Failure?
Main tie closes and utility bus disconnected
When would the DC EMER BUS appear on the DC electrical synoptic page?
- One of two sources failed OR
- Bus is faulted and both sources of power are removed
What would you lose if the DC EMER BUS failed?
Fire protection
Where would the ESS TRU 2 Transfer Contactor be visible and what would cause it to close?
Between ESS TRU 1 and ESS TRU 2 on top right of synoptic page.
“Multiple malfunctions”
What would cause the ADG to auto deploy?
ADCU (auto deploy control unit) deploys when:
1. AC Bus 1 and 2 unpowered
2. No weight on wheels
3. Generator was last power source in use
Which buses will power with ADG deployed and no other power source?
ADG Bus which powers AC ESSENTIAL / DC ESSENTIAL via the ESS TRU. DC Battery bus is also powered through the ESS tie.
