ATA 24 - ELECTRICAL POWER

• HOT BUS 1 and HOT BUS 2 are permanently supplied. On batteries only, the STATic INVerter connected to battery 1 supplies the AC STAT INV BUS. When the speed is lower than 100 knots, the emergency generator is deactivated.

• IDG 1(2) OIL OVHT warning message appears when the IDG oil outlet temperature is above 180°C.

• IDG 1 and 2 are monitored by respective GCUs (Generator Control Unit)

• CLASSIC:

- APU Generator is controlled by APU GCU

- GPU is controlled by GPCU (Ground Power Control Unit)

• ENHANCED:

- APU Generator and Ground power are controlled by a single computer called GAPCU (Ground Power and APU Power Control Unit)

• Each GCU is powered by its related IDG’s Permanent Magnet Generator (PMG) and, as a backup, by BAT BUS BAR

• APU GEN can supply the entire a/c network if no other elec power sources are

available. APU can provide elec power up to 41000 ft

• Ground power elec power has priority over APU elec power

• As soon as Ground power or APU elec power are set on, BTC 1 and BTC 2 close supplying the entire A/C network.

• EGIUs (Electronic Generation Interface Unit) converts GCUs/GPCU/APU GCU/GAPCU analog signals to digital format and feed SDACs

• APU provides elec power when N is above 95%

TRICK: if Maintenance Bus switch cannot be set on “ON”, TR2 is probably faulty

• BUS TIE Priority logic:

- IDG

- External power

- APU

- Opposite IDG

• APU has its own battery (located in the aft cargo compartment)

• A/C can be refueled on batteries only for max 10 minutes

• In case of AC ESS BUS power loss, the upper ECAM DU is no longer supplied, and the Engine/Warning

Display (EWD) is automatically transferred to the lower DU.

• If oil outlet temperature is above 185°C, the FAULT legend comes on amber on the IDG pushbutton.

The IDG P/B FAULT legend comes on if the IDG oil pressure is less than 140 PSI or if the IDG oil outlet temperature is above 185°C.

In both conditions, the IDG must immediately be disconnected.

If the temperature reaches 200°C, a solder fuse melts and automatically releases the disconnect mechanism to open the IDG disconnect clutch.

• The APU generator is not interchangeable with the Integrated Drive

Generators (IDGs). In case of oil temperature above 185°C, the ECB

commands an immediate shut down of the APU.

• If the GND/FLT buses are supplied (MAINT BUS switch on) and TR2 has an internal overheat (T above 172°C) the MAINT BUS switch trips off because relay 6XX is de-energized-no power to the GRD/FLT buses.

• After a thermal disconnection (T above 200°C), the IDG must be replaced.

• The Generator Control P/B has ON and OFF/RESET functions.

Switch all power off and then on again to reset the fault logic; this is called a cold reset. Most fault protections allow two

reset attempts and then the reset function is inhibited.

• (CSM/G) Three phase 115/200V AC, 400HZ, 5KVA.

The emergency AC generator has priority to supply the AC and DC-A STATic INVerter transforms the direct current from battery 1 into a single-phase alternating current (1 KVA)

• CSM/G = Constant Speed Motor / Generator

• In case of manual IDG 1 disconnection due to smoke, Generator Line Contactor (GLC) 1 opens.

Generator remains energized and supplies one fuel pump in each wing tank.

• Battery 2 supplies the DC ESS BUS and battery 1 supplies the STATic INVerter (STAT INV), which supplies the AC ESS BUS

• There are three identical and interchangeable Transformer Rectifiers (TR): TR 1, TR 2 and ESSential TR, each with 200 A, 28 VDC

• The ESSential TR operation is identical to that of TR 1 and TR 2. ESS TR fault signal is sent to Flight Warning Computer (FWC) 1 and 2.

• The two batteries are identical and interchangeable.

Each battery ventilated by two ducts.

• The differential pressure between the cabin and the outside is used to provide battery ventilation.

• In normal flight the batteries are uncoupled to the DC Bat BUS via BCL (Battery Charger Limiter)

• Loss of main generators

- BAT 1 AC → ESS BUS (Via Static Inverter)

- BAT 2 DC → ESS BUS

ENGINE ELECTRICAL POWER

• In cold conditions, due to the high oil viscosity, the oil pressure increases, the cooler bypass valve opens; oil runs in the IDG internal circuit.

• If the temperature rises above 147°C, the ELEC ECAM page is automatically displayed and the temperature indication flashes. If the temperature exceeds 180° C, the indication turns from green to amber. 185 fault light is on GEN.

• In case of oil overheat or drop of oil pressure, the amber IDG FAULT light comes on and the ECAM system is triggered.

• The Delta Pressure pop-out Indicator (DPI) can be reset up to 3 times prior to

IDG removal if these conditions are fulfilled.