Electrical Atlas Flashcards
During takeoff if the right engine generator fails, what happens to the utility and galley power?
Both utility and galley buses will be shed
Where is the ground service switch which is used to power the ground service bus located?
Forward cabin flight attendant panel
In flight, the left engine is shut down. What electrically powered items are lost?
Both Utility buses
The left centre fuel boost pump
Both Recirc fans
The C2 hydraulic pump
The AVAIL light on the external power switch is an indication of what?
The external power cart is plugged in and the volts and frequency are within limits
What is accomplished by pushing the AC Bus Tie Switch to AUTO?
Arms the automatic operation of the AC and DC Bus Tie Breakers
What causes the Standby Power Bus OFF light to illuminate?
Loss of the standby AC or DC bus
The Standby power switch in the OFF position
What will cause the Generator Drive light to illuminate?
High oil temperature; or
Low oil pressure
What normally powers the Battery Bus?
The left DC bus
Inflight the left generator trips off.
What electrical buses are lost?
The two (2) UTILITY buses
Galley Buses
Which bus is powered automatically when external power is plugged in?
The ground handling bus
What is the priority for powering the electrical systems?
GPU
ONSIDE ENG GPU
APU
CROSS SIDE ENGINE GPU
With the APU supplying both electrical and pneumatic power, what happens as the first engine is started?
Both utility buses trip off
What electrical bus powers the fire detection systems?
Battery Bus
What electrical bus powers ENG/APU/CARGO fire extinguishing bottles?
The hot battery bus
What is an integrated drive generator (IDG)?
Generator and CSD (constant speed drive) in one casing using the same oil
What is required to enable the Captains flight instrument transfer bus to transfer with the loss of the left main AC?
Both the left and right Bus Tie Switches must be in AUTO
With the APU supplying both electrical and pneumatic power:
What happens as the second engine is started?
Only the utility bus for the engine being started trips off
During a triple channel approach, the left generator is lost at 140 feet:
What electrical bus, if any, is lost?
The Left Main AC Bus
With the APU supplying electrical power, what happens when the first engine starts (reaches idle RPM)?
The engine driven generator powers its respective main AC Bus only
With the Generator Control switch ON:
What automatically closes when the engine starts?
Generator breaker only
When will the APU generator control OFF light illuminate
When the APU Generator breaker opens due to a fault
What is powering the standby busses?
Left main AC; and
Left main DC
In a single engine scenario.
How can the flight crew maintain electrical system redundancy?
By starting the APU and using the APU generator if available
To what bus is the utility bus connected, when the utility bus switch is ON?
Respective main AC bus
With the bus tie switch in AUTO:
What causes the AC Bus ISLN light to illuminate?
Bus fault has occured
What does pushing the Generator Control switch off and then on accomplish?
It resets the fault trip circuitry
What does the run light on the APU control panel indicate?
That the APU is at operating speed
Will the GCB close automatically when the voltage and frequency of the respective IDG are within limits?
Yes
What has occurred if during flight an off light illuminates and the “ON” indicator is visible in the generator control switch?
A fault has occurred and the generator control circuit breaker has automatically opened.
What could cause the generator drive light to illuminate?
High oil temperature
Low Oil Pressure
How many electrical buses are there in the standby power system?
Four (4)
What is the backup source of power for the battery bus if the normal source is not available?
The main battery
The standby AC bus is normally powered by the?
Left main AC Bus
The standby DC is normally powered by the
The left main DC bus
With a loss of main AC and DC power what provides electrical power to the standby AC and DC buses?
The main battery
What does an ISLN light mean in the bus tie switch?
The switch is off or a fault has occurred
The ground handling bus can only be powered on the ground by?
APU or external power
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