Electrical Flashcards
The two basic principles of operation for the 737 Electrical System are (Select ALL correct answers):
Correct Answer 2, 4
1) There is no paralleling of the DC sources of power.
2) There is no paralleling of the AC sources of power.
3) Main Busses shed Transfer Busses inflight.
4) The source of power being connected to a Transfer Bus automatically disconnects an existing source.
Sources of AC power include _____. (Select ALL correct
answers)
Correct Answer 1, 2, 3
1) Battery through Static Inverters.
2) APU Generator
3) Engine-Driven Generators
4) Battery through Transformer Rectifier (TR) Units
Illumination of the Generator DRIVE light (amber) indicates the respective IDG experienced low oil pressure due to ________.
Correct Answer 4
1) IDG failure
2) engine shutdown
3) IDG auto-decouple due to high oil temperature
4) all of the above
Placing the GRD PWR switch ON _____.
connects external electrical power to both Transfer
Busses
The BUS TRANSFER switch”,” in the AUTO (guarded)
position”,” allows _______.
Bus Tie Breakers (BTB) to operate automatically
Which light(s) indicate(s) the APU generator is ready-to-load”,” but not powering a bus?
APU GEN OFF BUS (bright blue)
If neither AC Transfer Bus is powered by an IDG”,”
momentarily positioning either APU GEN switch to ON
______.
Correct Answer 4
1) connects APU generator power to both Transfer Busses
2) illuminates the opposite SOURCE OFF (amber) light
3) disconnects external power”,” if connected, from both
Transfer Busses
4) all of the above
When the APU generator is powering Transfer Bus 1”,”
Transfer Bus 2 can be powered with _____. (Select ALL of the correct answers.)
Correct Answer 1, 2
1) the APU Generator
2) IDG 2
3) External Power
4) Ground Service Bus 2
The APU generator”,” operating in flight as a single electrical source ______.
automatically sheds the Galley and Main Busses
Moving a GEN1 or GEN 2 (Generator) switch to ON _____.
Correct Answer 4
1) extinguishes the related GEN OFF BUS light
2) connects related IDG to Transfer Bus
3) disconnects previous source from the related Transfer
Bus
4) all of the above
If the aircraft takes off with the APU generator powering
both Transfer Busses”,” and the APU fails or is shut down”,” the _____ automatically connects IDGs to their respective Transfer Bus.
Automatic Generator On-line Feature
Illumination of the ELEC light (amber) _____ indicates a fault in the _____ Power System.
on the ground / DC or Standby
The Cross Bus Tie Relay automatically opens and isolates DC Bus 1 from DC Bus 2 ______.
at Glide Slope capture during a Flight Director or
Autopilot ILS approach
The _____ Bus is always connected to the battery.
Hot Battery
BAT DISCHARGE light (amber) illuminates when _____
battery discharge is detected in the Main Battery and/or
Auxiliary Battery.
excessive
