ELECTRICAL SYSTEM Flashcards
How many generators (incl APU) are needed to run the electrical system?
1
In flight, during a generator failure, what is automatically shed?
Main Galley Power
What is the main difference between when GEN 1 fails versus GEN 2?
GEN 1 is connected to the ESS BUS and SHED BUS while GEN 2 requires the AC ESS FEED button to be depressed
When the RAT deploys, what buses does it power?
AC ESS BUS
DC ESS BUS
AC SHED BUS
In an emergency, what does BAT 1 power?
AC ESS BUS through a static inverter
In an emergency, what does BAT 2 power?
DC ESS BUS
What are the electrical sources priority?
Generators
External power
APU
RAT
BATTERIES
GEARB
What are the electrical capacities of the generators and the APU?
90 KVA
3-phase
115 V
400 Hz
What are the electrical capacities of the RAT?
5 KVA
3-phase
115-200 V
400 Hz
What is the purpose of a TR (Transformer Rectifier)
Convert AC to DC
When will you see a green arrow connected to the battery?
Only when current is >1 amp
What are the limitations for pushing the IDG FAULT buttons?
Don’t depress for more than 3 seconds
Engine must be running or windmilling
Can only be reset on the ground
When will you get the IDG FAULT light?
High IDG Oil Temp, over 180 deg C
Low IDG Oil Pressure
When will the batteries start charging?
< 26.5 V
When will the battery contactors close?
AC BUS 1&2 not powered by GENS or other sources
Batteries need charging
How long are the batteries prevented from charging after an APU start?
30 minutes
During pre-flight inspection, what white lights should be present on the ELEC overhead panel?
None, lights should be out
When you turn the battery on, what is the max charging current allowed?
<60 A and decreasing within 10 seconds
What tells you, just by looking at the overhead panel, that the APU is powering the AC system?
AVAIL light on the APU START button AND AVAIL light on the EXT POWER button
When you start engine nr 2 first with the APU connected, what happens to the BUS TIE?
Opens, APU now powers AC BUS 1 and GEN 2 powers AC BUS 2
RAT & EMER GEN FAULT light is on, what could this mean when deploying the RAT?
Means you are running on batteries as it takes 8 seconds for the RAT to spool up
What is the MIN speed for the RAT to function properly?
140 kts
During landing, at what speed does the EMER GEN become unavailable?
125 kts
What happens below 50 kts during total electrical failure?
All displays go blank
VHF 1 goes off line
No NW Steering
What is the function of the Static Inverter?
To transform DC power from BAT 1 into 1 KVA of single phase 115V/400Hz AC power which then is supplied to the AC ESS BUS
How many types of Circuit Breakers does the A320 have?
Green: Monitored. ECAM msg after tripped for 1 min
Black: Non-monitored
Can you re-connect an IDG in flight?
No
AC Power (115V) can be provided by which power sources?
2 GEN
1 APU
1 EXT PWR
If the battery voltages are below the minimum, how do you charge them?
Make sure BAT pb:s are on and switch the EXT PWR ON
When does the RAT automatically deploy?
Electrical power to both AC BUS 1&2 is lost and speed is above 100 kts
What does the blue EXT PWR ON light mean?
External power is supplying the aircraft electrical systems
After IDG disconnection in flight, why do you get a GALLEY SHED indication on the SD?
It’s a reminder that the main galley has been shed automatically following the loss of one generator
Where is the ground power connector?
Near the nosewheel on the right side of the fuselage
What happens in case of a TR1 fault?
The conntactor of each TR opens automatically in case of overheat or minimum current. The other TR automatically replaces the faulty one. The ESS TR supplies the DC ESS BUS
Having started the APU with EXT PWR connected, how can you get the APU to power the electrical system?
By pushing the EXT PWR pb and thus disconnecting the EXT PWR
What powers the Emergency Generator?
The Blue HYD SYS via the RAT
You enter a cold and dark cockpit, what action is required before you check the battery voltages
You have to check that both batteries are OFF
What are the main functions of the Generator Control Unit (GCU)?
To control the frequency and the voltage output of the generators and protect the network by controlling the generator line contactors (GLC)
Which bus supplies the AC ESS BUS?
Normally AC BUS 1 but it can be supplied by AC BUS 2 via the AC ESS FEED pb
What is the capacity of the main batteries?
23 amp hours
What is the power source for the FACDEC?
The FADEC has its own alternator. If it fails it automatically switches to aircraft electrical power
When performing the preliminary flight deck preperation, what is the minmum battery voltage?
25,5 V
What do you do if batteries are below 25,5 V?
Select BAT Switches ON with EXT PWR connected and ON
Will the batteries completely drain if you leave the BAT switches in AUTO after AC power is removed?
No, Battery has cut-off logic at 22 VDC
How is DC BAT BUS normally powered?
Through DC BUS 1 via a DC TIE conntactor
What does a BAT FAULT light indicate?
Battery charging current is outside limits (BAT contactor opens)
What are the 3 times the batteries are connected to the BAT BUS?
APU start
Battery charging
AC BUS 1&2 not powered and airspeed is above 100 kts
What does the ON BAT light for the ADIRS indicate?
It’s illuminated amber if one or more IR:s is supplied by the aircraft battery.
It also comes on briefly during the beginning of a full alignment
How are the IDG:s cooled?
By fuel from the HP fuel pump drawn in from the fuel manifold and then returned to it’s respective outer tank. When the outer tanks are full they spill over to the inner tanks
If the IDG return fuel fills up the wing tanks, what occurs?
The Center Tank Pumps turn off until the wing tank quantity reduces by 1100 lbs
What is the function of the IDG:s?
To convert variable engine speed to constant speed for optimum generator speed?
What does the APU GEN FAULT light indicate?
The line contactor is open because of a fault detected by the GCU
What is the function of having the BUS TIE in the AUTO position?
- Allows the BUS TIE CONTACTORS to open and close automatically to maintain power to both AC BUS 1&2
- Allows a single source to power the entire system
- Allows connection of the APU and EXT PWR to the system
- Inhibits multiple sources to be connected simultaneously
How does the GALLEY pushbutton work in AUTO?
Sheds main galley and in-seat power if only 1 GEN (APU or ENG) is available in flight, OR only 1 ENG GEN is available on the ground
What is the function of the AC ESS FEED pb in the normal position?
To allow AC BUS 1 to power AC ESS BUS
How is the AC ESS FEED transfered from AC BUS 1 to AC BUS 2?
Automatically or Manually by selecting ALTN on the AC ESS FEED pb
What lights illuminates when the DC ESS SHED BUS fails?
Floor proximity emergency escape path markings
Overhead emergency lights
EXIT signs
What buses are powered by the emergency generator?
AC ESS BUS and AC SHED BUS
DC ESS BUS and DC SHED via ESS TR
What happens when you push the GEN LINE 1 pb?
- GEN 1 Line Contactor opens and the white OFF light illuminates.
- AC BUS 1 is powered by GEN 2 via the BUS TIE CONNTACTOR
- GEN 1 continues to power 1 fuel pump in each wing
What does an amber FAULT light in the GALLEY pb indicate?
At least one GEN:s load is above 100% rated power
When is it normal to see the ENG GEN FAULT light illuminated?
Prior to engine start
What does the red FAULT light on the RAT & EMER GEN pb indicate?
Normal AC power is lost and the emergency generator is not supplying power
When should the red FAULT light on the RAT & EMER GEN pb be expected?
During 8 seconds at RAT deployment and power up
Do pilots normally use the EMER GEN TEST pb?
No, maintenance function only
When should you select the GEN 1 LINE pb?
During smoke procedures
How long will it take to charge the batteries?
20 min
What is the output of the static inverter?
1 kVa
Is there more than one way to deploy the RAT?
Yes, RAT MAN ON from the HYD panel
How would you manually force the aircraft into emergency electrical configuration?
Select EMER GEN 1 LINE OFF
Select EMER ELEC PWR to MAN ON
- when power is available
APU GEN OFF
GEN 2 OFF
How would you know if the battery switch pb is in AUTO or OFF with no power connected to the aircraft?
The battery pb is slightly recessed and the green gear down lights are illuminated. Some cockpit lights are also available and can be an indicator
How much (percentage wise) electrical power is shed in the smoke configuration?
75%
What does the acronym GEAR-B stand for in regards to the electrical system?
Generator
EXT POWER
APU
RAT
BAT
What are the limits for the electrical generator indications to turn amber with regards to LOAD, VOLTAGE and FREQUENCY?
LOAD > 100%
VOLTS < 110 V
> 120 V
FREQ < 390 Hz
> 410 Hz
When will the IDG ECAM indication go from white to amber?
- Outlet oil temp > 185 deg C
- IDG is disconnected
- Low oil pressure
- Fault - engine running
- Fault - engine stopped
When will the AC ESS FEED pb FAULT light come on?
When the AC ESS BUS is not supplied with any power
When will the AC ESS SHED BUS shed power?
When only battery power is available
What does the TR:s in the electrical system accomplish?
Transforms 115 V AC power to 28 V DC power.
What is the amperage that the TR:s can output?
200 amp
What is the limits for the TR:s before the indications turn amber in regards to VOLTAGE and CURRENT?
VOLTAGE > 31 V
< 25 V
CURRENT Equal or less than 5A
What does the BAT 1&2 pb,on the overhead panel, control?
The BCL:s (Battery Line Contactors)
When will the BCL:s automatically connect the batteries to the DC BAT BUS?
- For APU starting
- Battery charging below 26.5 V
- With loss of normal and emergency power below 100 kts
When is the STATIC INVERTER activated?
If above 50 kts and only batteries are supplying power
What is the primary source of power for the DC BAT BUS?
DC BUS 1 with DC BUS 2 as a backup
What is the purpose of the DC BAT BUS?
To charge the batteries and supply power to the DC ESS BUS
What normally supplies power to the DC ESS BUS?
The DC BAT BUS
What is the back-up power sources for the DC ESS BUS?
- ESS TR from the EMER GEN
- BAT 2
When will the DC SHED BUS shed power?
When the DC ESS BUS is supplied by BAT 2 only. This will happen when the EMER GEN is operating with the landing gear extended
What does a voltage above 25.5 V ensure during the initial battery check?
That charge is above 50%
For how long can the batteries supply power if they are the only power source?
Approximately 20 min