FCOM Flashcards
The electrical power system consists of
three-phase 115/200 V 400 Hz constant-frequency AC
system and a 28 V DC system.
The electrical power system is constituted
2 engine generators and 1 APU generator
GCU
Generators Control Units
The main functions of each GCU are :
- Control the frequency and voltage of the generator output.
‐ Protect the network by controlling the associated generator line contactor.
GPCU
Ground Power Control Unit
What is the main function of GPCU?
Protects the network by controlling the external power contactor
GAPCU
Ground and Auxiliary Power Control Unit
What is the main function of GAPCU ?
Regulates, via the APU Electronic Control Box, the frequency and voltage of the APU generator.
Protects the network by controlling the external power contactor and the APU generator line contactor.
Which hydraulic system drives the emergency generator?
blue hydraulic circuit
What are the specific of emergency generator?
generator supplies 5 KVA of three-phase 115 and 200 V 400 Hz power
GCU
Generator Control Unit
/What are the main functions of GCU
- Keeps the emergency generator at a constant speed,
- Controls the generator’s output voltage,
- Protects the network by the controlling the emergency generator line contactor, and
- Controls the emergency generator start-up.
What STATIC INVERTER does?
A static inverter transforms DC power from Battery 1 into one KVA of single-phase 115 V 400 Hz AC power, which is then supplied to part of the AC essential bus
At what speed STATIC INVERTER activate?
When the aircraft speed is above 50 kt, the inverter is automatically activated, if only the batteries are supplying electrical power to the aircraft, regardless of the BAT 1 and BAT 2 pushbutton positions.
When the aircraft speed is below 50 kt, the inverter is activated, if
only the batteries are supplying electrical power to the aircraft, and both BAT 1 and BAT 2 pushbuttons are on
Explain TRs
Two main transformer rectifiers, TR 1 and TR 2, supply the aircraft’s electrical system, with up to 200 A of DC current.
A third (identical) Transformer Rectifier, the ESS TR, can power the essential DC circuit from the emergency generator, if
the engine and APU generators all fail, or if TR 1 or TR 2 fails.
How many batteries are installed?
Two main batteries, each with a normal capacity of 23 Ah, are permanently connected to the two hot buses.
BCL
Each battery has an associated Battery Charge Limiter
What is the main function of BCL?
The BCL monitors battery charging and controls its battery contactor
Monitored Green CBs
When out for more than 1 min, the C/B TRIPPED warning is triggered on the ECAM
Black CBs
Non-monitored
Yellow ring on CBs
there are yellow rings on the C/B’s, which must be pulled when flying on batteries only
Wing Tip Brake (WTB) C/Bs
The Wing Tip Brake (WTB) C/Bs have red caps on them to prevent them from being reset.
The flight crew can clear the ECAM C/B TRIPPED caution by pressing:
The EMER CANC pb: When pressed, this pushbutton clears and inhibits the ECAM C/B TRIPPED caution for the remainder of the flight, or
‐ The CLR pb: When pressed, this pushbutton only clears the ECAM C/B TRIPPED caution. If the C/B remains pulled, any additional tripped circuit breakers on the same panel will not be detected, and the ECAM will not trigger the caution. However, if the C/B is pushed, any additional tripped circuit breakers will be detected, and the ECAM will trigger the caution again.
Priority of Generators ?
GEN 1 and 2 when operating have priority over the APU generator and over external power.
External power has priority over the APU generator when the EXT PWR pb switch is ON
Each engine-driven generator supplies
its associated AC BUS (1 and 2) via its generator line
contactor (GLC 1 and GLC 2)
AC BUS 1 normally supplies
the AC ESS BUS via a contactor
TR 1 normally supplies
DC BUS 1, DC BAT BUS, and DC ESS BUS.
TR 2 normally supplies
DC BUS 2.
The two batteries are connected to the
DC BAT BUS, if they need charging. When they are fully charged, the battery charge limiter disconnects them.
The system automatically replaces the failed generator, with the
APU GEN, if available, or
Other engine generator.
FAILURE OF AC BUS 1
AC BUS 2 can supply AC ESS BUS, and ESS TR can supply DC ESS BUS, both via the AC ESS FEED pb. This is done automatically with the ACESS FEED Auto Switching
DC BUS 2 supplies DC BUS 1 and DC BAT BUS automatically after 5 s.
FAILURE OF ONE TR
The other TR automatically replaces the faulty one.
The ESS TR supplies the DC ESS BUS
The contactor of each TR opens automatically, in case of :
Overheat
Minimum current
FAILURE OF TR 1 AND TR 2
DC BUS 1, DC BUS 2, and DC BAT BUS are lost. The DC ESS BUS is supplied by the ESS TR.
If both AC BUS 1 and AC BUS 2 are lost and the aircraft speed is above 100 kt,
the Ram Air Turbine (RAT) extends automatically. This powers the blue hydraulic system, which drives the emergency generator by means of a hydraulic motor.
The emergency generator supplies
the AC ESS BUS, and the DC ESS BUS via the ESS TR.
What happen to emergency generator if we lower the landing gear?
the emergency generator is no longer powered, and the emergency generation network is automatically transferred to the batteries and the static inverter, and the system automatically sheds the AC SHED ESS and DC SHED ESS buses
When the aircraft is on ground :
‐ Below 100 kt, DC BAT BUS is automatically connected to
the batteries
When the aircraft is on ground :
Below 50 kt, AC ESS BUS is automatically
shed, leading to the loss of all display units
On ground, if only the batteries are powering the emergency generation network, APU start is only available when the speed is
below 100 kt.
SMOKE CONFIGURATION
In this configuration the main busbars are shed
In smoke configuration the fuel pumps are connected upstream of the
GEN 1 line connector
The batteries are connected to the DC BAT BUS in the following cases
- APU starting (MASTER SW pb-sw at ON and N < 95 %).
- Battery voltage below 26.5 V (battery charge). The charging cycle ends when battery charge current goes below 4 A.
- Loss of AC BUS 1 and 2 when below 100 kt (EMER GEN not supplying).
If AC BUS 1 and 2 are not energized and the EMER GEN is not supplying:
- Battery 1 supplies the AC STAT INV BUS, and, if speed is greater than 50 kt, the AC ESS BUS.
- Battery 2 supplies the DC ESS BUS.
Automatic battery contactors open when:
‐ The aircraft is on the ground
‐ The BAT pb switches are at AUTO
‐ The main power supply (EXT PWR + GEN) is cut off
‐ Battery voltage is low.
IDG oil outlet overheats (above
185 °C)
GEN 1 (2) pb-sw FAULT light illimunated
Lights up amber, and an ECAM caution comes on, if:
- The associated generator control unit (GCU) trips it.
- Opening of the line contactor
Battery voltage is normally green, but becomes amber if
V > 31 V or V < 25 V
Battery current is normally green, but becomes amber if
discharge current > 5 A.
DC BAT indication is normally in green. It becomes amber, if
DC BAT voltage ≤ 25 V
The TR voltage is normally in green. It becomes amber, if
V > 31 V, or V < 25 V
The TR current is normally in green. It becomes amber, when the
TR current ≤ 5 A.
The IDG legend is normally white, but becomes amber, if:
Oil outlet temperature > 185 °C.
Oil pressure gets too low.
IDG becomes disconnected.
