Electrical Flashcards
How many NiCad batteries are there on the aircraft?
3
MAIN, AUX, STBY
How many engine-driven DC starter-generators are there on the aircraft?
2 (1 each engine)
How many Transformer Rectifier Units (TRUs) are there on the aircraft?
2
How many APU generators are there on the aircraft?
1
T/F: The electrical system comprises both a direct current (DC) system and an alternating current (AC) system
TRUE (28VDC and 115VAC)
T/F: DC power to the electrical system is supplied by two engine-driven DC generators only.
FALSE, 3 batteries, 2 TRUs, the APU Generator, and External Power can be used
T/F: Circuit breaker panels can be found in the left and right main landing gear wheel wells.
TRUE (in the AC Contactor boxes)
How many circuit breaker panels are there in the flight compartment?
4
Which of the following are NOT electrical buses?
answer with which of the following ARE electrical buses?
L & R Main Bus L & R Secondary Bus L & R Essential Bus L & R AC Bus Battery Bus (Note: emergency bus is NOT a bus)
The aircraft is equipped with which of the following batteries?
Main
Auxiliary
Standby
Which batteries are used for engine starting when ground power is not available?
Only MAIN and AUX batteries
How long will the batteries power the aircraft if normal electrical power fails?
up to 60 minutes
How many battery switches are there?
4 switches on DC control panel (Battery Master, MAIN BATT, AUX BATT, and STBY BATT)
T/F: If the battery master is in the OFF position, the other batteries can still be used to power the aircraft?
FALSE
T/F: When the battery master is in the OFF position, all battery power is turned off no matter what position the other switches are in.
TRUE
If the battery is being charged at a 100% rate of charge, how will it be depicted on the MFD Battery page?
1.00 because that is 100% normal charge rate
How is a battery that is discharging displayed on the MFD Electrical page?
It will have a “-“ sign and a percent discharge (ie. -.30 = 30% over maximum rate of discharge)
When the battery temperature is within limits, what color does it display as on the MFD Electrical page?
White
When the battery temperature exceeds normal limits, what colors would display on the MFD Electrical page?
Amber
or
Red
If any battery temperature is 50 degrees C to 65 degrees C, what color does the battery temperature display as on the MFD Battery page?
Amber
Where can the GPU be connected to the aircraft for DC power?
Left forward fuselage
When connected to external power on the ground, DC EXT PWR ON is displayed in what color?
Green when connected
T/F: The EPCU protects the system from too high and too low DC power voltage from the DC external power source.
TRUE
After engine start, how many volts does the DC generator provide?
28VDC
Where are the Transformer Rectifier Units (TRUs) located?
Nose of aircraft
TRUs change 3-phase 115VAC to what?
28VDC
During normal operation, which busses do the TRUs power?
L or R Secondary (“Feeder”) buses
A L TRU caution light will illuminate when what happens?
TRU is offline or fails
On the ground, what busses does the APU generator provide power for?
L & R Main bus
L & R Secondary Bus
L & R Essential Bus
What does it mean when a plus sign (+) is displayed in front of a value on the MFD Electrical page?
Indicates an overload of the power source
The entire DC electrical system can still be powered when up to how many power sources have failed?
2 power sources
When does the EPCU send a signal to the generator to trip it offline during a Main DC bus fault?
If the fault persists for 5 seconds or more
If the Right Main Bus has a bus fault, which battery is disconnected from the system?
The Main Battery
T/F: If a Secondary bus fault occurs, the increased current will trip the circuit breaker for the respective TRU.
TRUE
In addition to an inoperative TRU, what is required for the EPCU to enter emergency mode?
Airplane in air
Both DC generators unavailable
In addition to a dual DC Generator failure, what is required for the EPCU to enter emergency mode?
Airplane in air
At least 1 TRU unavailable
T/F: In EPCU emergency mode, the batteries are the main source of power.
TRUE
When in EPCU emergency mode, which busses automatically disconnect from the batteries?
Main busses
What is the voltage output of the AC generators?
115VAC 3-phase
Where are the AC generators mounted on the aircraft?
On each engine’s propeller reduction gearbox
How many external AC power ports are there on the aircraft?
1 AC power port (on inboard side of right engine nacelle)
When the aircraft is powered by external DC power, which busses are powered?
L & R Main
L & R Secondary
L & R Essential
T/F: When a DC generator fails, the Main Bus Tie switch must be manually selected to keep the associated Main DC bus powered.
FALSE, EPCU can change the status of the bus tie automatically
Which switch would pilots use to connect the main battery to its associated Main feeder bus?
The MAIN BATT switch
T/F: The electrical system has a single hot battery bus to keep certain items powered at all times.
TRUE
T/F: The hot battery bus can be powered by any of the 3 batteries.
FALSE, standby battery only
At what point will DC electrical bus load shedding begin?
3 (or more) DC source failures
In EPCU Emergency mode, the _____ are the main power source for the available DC busses.
Batteries
The AC generators connect to the system when the engines are running, GEN 1 and 2 switches are selected ON, and _____.
condition levers are in MIN to MAX range
