Electrical Flashcards
When should an open circuit breaker be reset?
If the affected component is required for safe flight and landing
What is indicated if the R GEN switch displays an amber OFF light?
The GCU has tripped
When does the ARM position of the emergency power system switches allow the emergency power system to activate?
When the ESS DC bus voltage drops below 20 volts, or after 2.5 G impact
What buses will be powered with inoperative generators and APU, if HMG is selected on?
Both standby AC buses,
both ESS DC buses, and
the ESS AC bus
What is the rating of the hydraulic Motor Generator (HMG)?
10 kva
How is the HMG powered?
Left hydraulic system pressure or PTU (provided fluid is in the left system)
Selecting the L Bus tie switch to ISLN position will?
Isolate the L main AC bus from all power except the left IDG
The battery voltage which will cause the E BATTS to come on is?
< 20 volts DC
The minimum main battery voltage is?
22 Volts
What 3 items will illuminate the battery switch capsule lights?
When L & R batteries are powering the L-R ESSENTIAL DC BUS
whatever the aux hydraulic pump is on
During APU start
Which battery is used to close the main door from the outside door switch?
Only the right battery, which is wired to the main door switch
What is an IDG and how does it work?
Integrated Drive Generator - it operates much like a constant speed transmission. As the engine speed changes, the CSD maintains the generator at a constant speed
The function of the L-R Main TRU switch is?
The on side MAIN AC BUS powers each main TRU.
In the unlikely event that the on side MAIN AC BUS should fail, the L-R TRU can be selected to the opposite side MAIN AC BUS to restore the TRU and its respective MAIN DC BUS
In what situation can a TRU power more than one bus, and which buses can it power?
When the HMG and left ESS/ right ESS switches are IN/ON,
the AUX TRU can power both ESS DC BUSES
If the right main TRU fails, what should automatically power the right main DC bus?
AUX TRU
If ground service bus switch is selected ON, what will power that bus?
DC external power or the battery if external power is not available
Which batteries are activated when the external battery switch is turned on?
Both main batteries
What item will be lost with only one AC power source operating in flight?
Galley power
What type of Main DC Batteries are installed in the 550?
NICAD batteries
24volt, 53 amps
A no brake power transfer can occur between the APU and what other electrical component?
An engine driven generator (IDG)
How are Bus Tie isolation contactor relays controlled?
By isolation switches on the cockpit overhead panel,
the Generator Control Unit (GCU), or
the Bus Power Control Unit (BPCU)
What is indicated by an AMBER OFF light in either engine generator switch?
The IDG has been isolated by the GCU and the BPCU
How is the left main TRU powered when the L MAIN TRU switch on the overhead panel is selected to R AC
In this configuration, the L MAIN TRU receives power from the R MAIN AC bus
What is the indication associated with a batterie charger failure?
An amber BATT CHGR FAILL CAS message will illuminate
From where can the E inverter receive power?
From LEFT or RIGHT ESS DC bus ( normally the left bus supplies power if the E inverter is required)
The AUX TRU is capable of providing power to both the left and right ESS DC buses simultaneously during what type of electrical operation?
Standby electrical power (HMG)
From where do the battery chargers receive their power inputs?
From L and R MAIN AC buses
How many E Batts are installed and where are they located?
Four
Located in the LEER, REER, AEER
How are the E Batts charged?
Left instrument battery- Left standby AC bus
Right instrument battery- Right standby AC bus
Forward lighting battery- left main AC bus
Aft lighting battery- right main AC bus
Below what voltage will the main batteries require maintenance deep cycle recharge?
7 volts
What items are capable of being powered from the battery tie bus?
- Aux hydraulic pump
- APU starter
- ESS DC buses
How long does it take to recharge an undamaged, discharged battery?
90 mins
What 3 items will illuminate the battery switch capsule lights?
- When the batteries are powering the ESS DC bus
- Aux pump is selected on
- when starting the APU
Which buses will the HMG power?
L-R STANDBY AC BUS and AUX TRU, which supplies power to the L-R ESS DC buses and the ESS AC bus, phase A through the E inverter.
How many TRU’s are normally operating inflight?
Four total
Which TRU is not dedicated to a single bus?
AUX TRU
If a ground service bus switch is selected ON, what will power that bus if DC external power is connected to the aircraft?
DC external power
If a ground service bus switch is selected ON with no external power connected to the aircraft, where will the ground service bus get its power?
From the right battery
Inflight, how is the ground service bus normally powered?
From the R MAIN DC BUS
Whenever the ground service bus is turned ON, what light turns on?
Lower Beacon
Whenever the external battery is turned on, what light turns on?
Lower beacon
What buses are powered with external DC power cart connected to the aircraft?
- L and R ESS DC
- L and R MAIN DC
- GND SVC BUS
- ESS AC ( phase A only, through the E inverter
What electrical components are located underneath the forward floor
TRUs and E inverter
