Study Guide: Electrical Flashcards
757/767: According to the graphic, the right utility bus OFF light is illuminated. What is
the cause for its illumination?
The right utility bus is unpowered
757/767: According to the graphic, the L GEN DRIVE DISC DRIVE light is illuminated.
What is the cause for its illumination?
The associated generator drive oil temperature is high or oil pressure is low
757/767: According to the graphic, the standby power bus OFF light is illuminated. Which bus(ses) is/are not powered?
Standby AC, standby DC, or battery bus(ses) not powered
757/767: According to the graphic, what is providing power to the standby busses?
Left main AC and DC
757/767: When external or APU electrical power is available on the ground, which bus is
automatically powered?
Ground handling bus
757/767: When the associated AC bus tie breaker is armed for automatic operation, the
AC busses are powered according to the following system priorities:
Respective IDG, APU generator, opposite IDG
757/767: As the first engine is started with APU supplying electrical and pneumatic
power, what load shed occurs?
Both utility and all galley busses load shed
757/767: During flight, the hydraulic motor generator (HMG) automatically starts and
supplies AC and DC power:
When primary AC power is lost on both main AC busses during flight
757/767: The center busses transfer from the left main busses directly to the static
inverter and the hot battery bus when:
At least two generators are operating and three autopilots are armed for an
autoland approach
757/763: On a three autopilot approach with a LAND 3 indication, what will the ASA
indicate if an engine-driven generator is lost below 200 feet AGL without the APU
running?
LAND 3
757/767: Once commanded to operate, are there limitations associated with how long
the hydraulic motor generator (HMG) can run?
No, there is no time limit for HMG operation
757/767: According to the graphic, what is providing power to the Ground Handling bus?
External electrical power
757/767: The main aircraft battery and the APU battery are connected to their own
respective battery chargers. Both battery chargers are powered by the:
Ground service bus
757/767: The integrated drive generator (IDG) oil is cooled by:
A fuel/oil heat exchanger
757/767: The main DC electrical system is powered:
By the transformer-rectifier units (TRU’s) powered by the main AC busses
753/764: During hydraulic motor generator (HMG) operations, what is the status of the
IRUs?
All three IRU’s remain powered
752/763: Hydraulic motor generator (HMG) operation automatically switches the Captain’s RDMI to:
The center IRU
757/767: In the case of a generator overload, which busses automatically load shed?
Associated utility and galley busses
757/767: The ground service bus is normally powered by the:
Right main AC bus
767: The left recirculation fan is powered by the:
Left utility bus
757/767: The associated utility and galley busses have shed due to a generator overload. What is required to restore power to the bus?
The utility busses (and therefore galley busses) must be reset manually
757/763: If primary AC power is lost on both main AC busses during flight, the hydraulic motor generator (HMG) automatically starts and supplies AC power to the:
Left and right AC transfer busses, standby AC bus via the left AC transfer bus,
and Captain’s flight instrument transfer bus
752/763: According to the graphic, which electrical busses are still being powered? (HMG not operating)
Hot battery bus, battery bus, standby DC bus, standby AC bus
757/767: According to the graphic, the DISCH light is illuminated. The main aircraft battery:
Is discharging
757/767: According to the graphic, the BUS TIE ISLN light is illuminated. This occurs when:
The AC bus tie breaker is locked open from a fault trip
