Electrical Flashcards
If a circuit breaker is open, when should it be reset?
If the affected component is required for safe flight and landing
A No-Break Power Transfer (NBPT) can only occur between an APU generator and:
An Engine Driven Generator (IDG)
The two bus tie isolation contactors are controlled by the:
Switches on the cockpit overhead panel, generator control units (GCUs), and Bus Power Control Units (BPCUs)
Speed brake consideration when the standby electrical power system (HMG) is in operation:
May be used provided operation is slow (3 seconds for full movement)
If the R GEN switch indicates an AMBER OFF light, what is indicated?
The IDG has been isolated by the BPCU
If the L MAIN TRU switch is selected to the R AC position, what happens?
The L MAIN TRU will receive power from the R MAIN AC bus
During normal operations (IDGs powering the aircraft), the Ground Service Bus receives power from which bus?
Right Main DC bus
When does the “ARM” position of the Emergency Power System switches allow the emergency power system to activate?
Essential DC bus < 20 VDC
If one battery charger fails, what happens?
Amber BATT CHGR FAIL (L or R)
If the HMG is selected on due to inop generators and APU, what buses will be powered?
Both Standby AC buses, Both ESS DC buses and the ESS AC bus
The E-Inverter can receive power from what bus?
Left or Right ESS DC buses
The AUX TRU is capable of providing power to both the left and right ESS DC buses during what operations?
HMG
Where do the battery chargers receive their power?
From the respective Main AC Bus
What will selecting the L Bus tie switch to the ISLN position do?
Isolates the L MAIN AC Bus from all power except the left IDG
How many emergency batteries are installed in the airplane?
Four, located in the LEER, REER and BEER(AEER)
How are the emergency batteries charged?
Left - L STBY AC Bus
Right - R STBY AC Bus
Forward Lighting - L MAIN AC Bus
Aft Lighting - R MAIN AC Bus
What minimum battery voltage will cause the E-BATTs to come on?
< 20VDC
What is the minimum main battery voltage? (For APU start?)
22 VDC
Below what voltage would the main batteries require a deep cycle recharge?
< 7 VDC
How long does it normally take for a battery deep cycle?
24 hours
If the batteries actually fell to 20 volts, how long would it take to fully recharge?
90 minutes
What 3 events will illuminate the battery switch lights?
- When L&R batteries are powering the L&R Essential DC Bus
- When the AUX HYD PUMP is ON
- During APU Start
Which battery is used to close the main door from the outside door switch?
Right Battery, which is wired to the main door switch
What is an IDG and how does it work?
Integrated Drive Generator - constant speed drive maintains the generator at a constant speed as the engine speed changes
