Electrical Flashcards
What is the minimum battery voltage for APU start?
23 volts
Primary electrical power is provided by ______ engine driven integrated drive generators (IDGs).
two
What occurs when a source of power is connected to a bus system?
it automatically disconnects an existing source
The APU generator can supply power to ____________ on the ground and inflight
both transfer busses
A GRD POWER AVAILABLE light provides flight deck indication that AC ground power is ____________________.
connected to the aircraft and meets aircraft power quality standards
If the BUS TRANS switch is in the AUTO position and the source powering the transfer bus is disconnected or fails, the source powering the opposite transfer bus _________________ through the BTBs.
automatically picks up the unpowered transfer bus
For single generator operation, the system is designed to ___________.
shed electrical load incrementally
The amber DRIVE caution light is illuminated when ____ oil is sensed in the IDG.
low
After the IDG disconnect switch is used to disconnect the IDG from the engine, it _________ possible to reactivate the IDG in flight.
is not
IDG low oil pressure can be caused by which of the following:
() all answers are correct
() IDG automatic disconnect due to high oil temperature
() IDG disconnected through the generator drive DISCONNECT switch
On the ground, an amber _______ light illuminates to indicate the DC system or standby system equipment has failed. This light is inhibited in flight.
ELEC
The three transformer rectifier (TR) units convert 115-volt AC to _______ DC.
28-volt
Inflight, an amber TR UNIT light illuminates _________.
TR1 or TR2 and TR3 has failed
A fully charged battery has sufficient capacity to provide electrical power for a minimum for ________.
30 minutes
An amber BAT DISCHARGE light illuminates when _________.
excessive battery discharge is detected
During normal operation the guarded Standby Power Switch will be in _____ and the battery switch will be _____.
AUTO; ON
An illuminated STANDBY Power (PWR) OFF Light indicates one or more of the following buses are unpowered
) all answers are correct
() AC standby bus, DC standby bus
() battery bus
With the STANDBY POWER Switch in AUTO (guarded position) in flight or on the ground with the loss of all AC power, the AC standby bus is powered by __________________ and the DC standby bus is powered by _____________.
battery through static inverter; battery
Maintenance (MAINT) Test Switch on the AC and DC Metering Panel is typically used by ________.
maintenance
What is the function of the DC Meters Selector?
selects the DC source for the DC Voltmeter and the DC Ammeter indications
What is the function of the AC Meters Selector?
selects the AC source for the AC Voltmeter, AC Ammeter and frequency meter indications
On the B737-900ER, which switch can be used to remove power from the left and right recirculation fans, forward and aft door area heaters, lavatory water heaters, ECS fan, all 115V AC galley busses, 115V AC shaver outlets, logo light, and potable compressor?
CAB/UTIL Switch
On the B737-900ER, which switch can be used to remove power from 115V AC audio entertainment equipment, 115V AC video entertainment equipment, 115V AC airphone equipment, and passenger seat electronic outlets?
IFE/PASS SEAT Switch
With ground power available, moving the Ground (GRD) Power Switch to the ON position
() all answers are correct
() removed previously connected power from AC transfer busses
() connects ground power to AC transfer busses if power quality is correct
What light on the overhead panel illuminates if the transfer bus is not being powered?
TRANSFER BUS OFF
What light on the overhead panel illuminates if the transfer bus is not powered by the source selected by the related generator switch?
SOURCE OFF
What light on the overhead panel illuminates if the IDG is not supplying power to the related transfer bus?
GEN OFF BUS
On the B737-800, moving the Generator (GEN) Switch to ON, connects ___________ by disconnecting the previous power source and closing the generator circuit breaker.
IDG to the AC Transfer Bus
What light on the overhead panel illuminates if the APU is running and not supplying power to a bus?
APU GEN OFF BUS
Which switch provides manual control of ground service busses enabling servicing of the aircraft using external power without activating AC transfer busses?
GROUND SERVICE Switch on the FWD Attendant Panel
