SINGLE AISLE TECHNICAL TRAINING MANUAL MAINTENANCE COURSE M35 LINE MECHANICS (V2500A5.ME)

 SINGLE AISLE 
 TECHNICAL TRAINING MANUAL 
 MAINTENANCE COURSE - M35 LINE MECHANICS
(V2500-A5/ME) 
 ELECTRICAL POWER 



This document must be used for training purposes only

Under no circumstances should this document be used as a reference

It will not be updated.

All rights reserved
No part of this manual may be reproduced in any form,
by photostat, microfilm, retrieval system, or any other means,
without the prior written permission of AIRBUS S.A.S.



SINGLE AISLE TECHNICAL TRAINING MANUAL

ELECTRICAL POWER
GENERAL
System Diagram Description (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Electrical Power Level 2 (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Emergency Electrical Power Logic Description (3) . . . . . . . . . . . . . 120

AC AND DC LOAD DISTRIBUTION

Refueling on Battery (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128

ELECTRICAL POWER GENERATION SYSTEM (EPGS)

DC GENERATION

IDG Cooling System (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
IDG Monitoring (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
AC Main Generation D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
AC Auxiliary Generation General Description (2) . . . . . . . . . . . . . . . 22
External Power Supply General Description (2) . . . . . . . . . . . . . . . . 24
AC/DC Ground Service Distribution D/O (3) . . . . . . . . . . . . . . . . . . 28
Bus Tie Logic D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Galley Supply D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
AC/DC Bus Off Warnings Logics (3) . . . . . . . . . . . . . . . . . . . . . . . . . 54
AC Generation Interfaces (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

DC Main Generation D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
Battery System D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 134
Battery Charge Limiter D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

ENHANCED EPGS

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IDG Cooling System (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
IDG Monitoring (2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
AC Main Generation D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68
AC Auxiliary Generation General Description (2) . . . . . . . . . . . . . . . 72
External Power Supply General Description (2) . . . . . . . . . . . . . . . . 74

# AC/DC Ground Service Distribution D/O (3) . . . . . . . . . . . . . . . . . 78
Bus Tie Logic D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
# Galley Supply D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
AC Generation Interfaces (3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108

MAINTENANCE PRACTICE (Classic & Enhanced EPGS)
IDG Removal and Installation (3) . . . . . . . . . . . . . . . . . . . . . . . . . . 110

AC EMERGENCY GENERATION
AC Emergency Generation D/O (3) . . . . . . . . . . . . . . . . . . . . . . . . . 114
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TABLE OF CONTENTS

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SINGLE AISLE TECHNICAL TRAINING MANUAL

SYSTEM DIAGRAM DESCRIPTION (1)
MAIN AC GENERATION
ENGINE GENERATORS
The aircraft electrical system is supplied by two engine driven
GENerators regulated in speed by integrated drives.
GEN 1 is driven by engine 1.
GEN 2 is driven by engine 2.
Engine generators characteristics are:
- 115/200 volts, three phase,

- 400 Hz,
- 90 kVA.

APU GENERATOR
A third AC generator driven by the APU can replace one or both main
engine generators throughout the flight envelope.
APU GEN characteristics are:
- 115/200 volts, three phase,
- 400 Hz,
- 90 kVA.

- 115/200 volts, three phase,
- 400 Hz,
- 5 kVA.

AC TRANSFER
The AC transfer circuit enables AC BUS to be supplied by any generator
or external power, via the Bus Tie Contactors (BTCs).
Generators are never connected in parallel on the same bus.
The two normal buses (AC BUS 1 & AC BUS 2) are supplied by the
available suppliers in the following priority:
- 1: onside generator (IDG),
- 2: external Power,
- 3: APU GEN,
- 4: offside generator.

AC DISTRIBUTION
AC BUS 1/2
Each engine generator supplies its related AC BUS.

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EXTERNAL POWER

AC ESS BUS

A ground EXTernal PoWeR connector enables all bus bars to be
supplied.
External power characteristics are:
- 115/200 volts, three phase,
- 400 Hz,
- 90 kVA minimum.

The AC ESSential BUS is normally supplied by AC BUS 1 or by AC
BUS 2 if AC BUS 1 fails.

EMERGENCY GENERATOR
An AC EMERgency GEN is driven by the Ram Air Turbine (RAT)
hydraulic circuit. It automatically provides emergency power in case of
failure of all main aircraft generators. Emergency generator characteristics
are:
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

AC ESS SHED BUS
The AC ESS SHEDdable BUS is supplied by the AC ESS BUS.

115/26V AUTO TRANSFORMER
A 115 volts to 26 volts single-phase autotransformer supplying a
normal 26 volts 400 hertz sub-busbar is connected to each main busbar

and to the AC ESS BUS.

SYSTEM DIAGRAM DESCRIPTION (1)

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SINGLE AISLE TECHNICAL TRAINING MANUAL
DC GENERATION
DC generation is accomplished by Transformer Rectifiers (TRs) 1 and
2. All TR characteristics are:
- maximum output of 200 A,
- 28V DC.
One essential TR unit replaces a faulty main TR to power the DC ESS
BUS.

DC DISTRIBUTION

- 115 volts, single phase,
- 400 Hz.

GROUND/FLIGHT BUSES
AC and DC GrouND/FLighT BUSes are normally supplied by the aircraft
network, or directly by the external power unit, upstream of the External
Power Contactor (EPC), without energizing the whole aircraft network.

GALLEYS

DC BUS 1 and DC BUS 2 are supplied by their related TR.

The main and secondary electrical circuits of the galleys are supplied by
AC BUS 1 and 2. The main electrical circuits are shed in single generator
operation.

DC BAT BUS

MAIN ELEC CONFIGURATIONS

DC BUS 1/2

The DC BATtery BUS is supplied by DC BUS 1 or by DC BUS 2 if
DC BUS 1 fails. Batteries can also supply the DC BAT BUS.

GROUND SUPPLY

DC ESS BUS

On ground, the complete circuit may be supplied by the external power
unit or by the APU generator.

The DC ESS BUS is supplied by the DC BAT BUS. In an emergency,
it is supplied either by battery 2 or by the essential TR.

DC ESS SHED BUS
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The DC ESS SHED BUS is supplied by the DC ESS BUS.

NORMAL FLIGHT CONFIGURATION

In normal flight configuration, each generator supplies its own
distribution network via its Generator Line Contactor (GLC). The two
generators are never electrically coupled.

BATTERIES

GROUND SERVICES

Two batteries can be connected to the DC BAT BUS. Each battery has
its own bus, HOT BUS 1 and HOT BUS 2. They are permanently
supplied. The battery capacity is 23 Ah with a nominal voltage of 24V
DC.

For ground service only, the AC and the DC GND FLT BUSes can
be supplied independently from the normal circuit.

STATIC INVERTER
On batteries only, the STATic INVerter connected to battery 1 supplies
the AC STAT INV BUS.
Static inverter characteristics are:
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

LOSS OF MAIN GENERATORS
In flight, in case of total loss of all the main generators, and before
the emergency generator connection, battery 1 will supply the AC
ESS BUS, via the STAT INV and battery 2 will supply the DC ESS
BUS. This is a transient configuration, during RAT extension or no
emergency generator available. When its parameters are correct, the
emergency generator comes on line and supplies the AC and DC ESS

SYSTEM DIAGRAM DESCRIPTION (1)

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BUSes. When the speed is lower than 100 knots, the emergency
generator is deactivated. The batteries supply the AC and DC ESS
BUSes. The DC BAT BUS is recovered. When the speed drops below
50 knots, the AC ESS BUS disconnects from the static inverter.

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SYSTEM DIAGRAM DESCRIPTION (1)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

MAIN AC GENERATION ... MAIN ELEC CONFIGURATIONS
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 

24 - ELECTRICAL POWER

SYSTEM DIAGRAM DESCRIPTION (1)

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ELECTRICAL POWER LEVEL 2 (2)

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GENERAL
There are two identical engine driven generators called Integrated Drive
Generators (IDGs). They are used as the main power source to supply
the A/C electrical network.
The IDG basically contains, in a common housing, a generator and a
Constant Speed Drive (CSD). The CSD gives a constant input speed to
the generator, which is required for a constant output frequency.
Each generator supplies 115V 400Hz AC to its own bus:
- generator 1 supplies AC bus 1,
- generator 2 supplies AC bus 2.
This supply is known as split operation, which means that the AC power
sources are never connected in parallel.
Each AC bus supplies a Transformer Rectifier (TR):
- AC bus 1 supplies TR 1,
- AC bus 2 supplies TR 2.
The TRs convert 115V AC into 28V DC to supply their associated DC

buses, DC 1 and DC 2.
DC bus 1 then supplies the DC BATtery bus.
The DC BAT bus can charge the batteries or receive power from the
batteries as a backup supply, if no other power sources are available.
The electrical system also includes two ESSential (ESS) Buses. One is
the AC ESS bus fed by AC bus 1 and the other is the DC ESS bus fed
by DC bus 1. These buses are used to supply the most critical A/C
systems.
This is the basic electrical system. We will now introduce some other
components which also supply the system.
The APU generator can also supply the entire electrical network.
On the ground, the aircraft electrical network can be supplied by an
external power source.
Any one of the power sources can supply the entire electrical network.
As no parallel connection is allowed on this A/C (split operation), we
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

have to give priorities to the different power sources in supplying the bus
bars.
AC 1 and AC 2 buses are supplied in priority by their own side generator,
then the external power, then the APU generator and then by the opposite
generator.

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

GENERAL
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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ELECTRICAL POWER LEVEL 2 (2)
SERVICING

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CHECK OF THE OIL LEVEL AND FILTER DPI
Each engine (HP rotor) drives its related Integrated Drive Generator
(IDG) through the accessory gearbox.
The drive speed varies according to the engine rating. The IDG internal
gearing, converts the variable gearbox frequency to a stable 400 Hz.
The IDG supplies a 115 V AC, 3-phase, and 400 Hz AC. At some
point, servicing will be required of the IDG. In this module you will
see a video that will demonstrate the correct servicing procedures of
the IDG.

Check the oil level and the filter Differential Pressure Indicator (DPI)
each 150 Flight Hours (FH) or each times the engine cowls are opened.
Depending on when the time schedule occurs there might be a reason,
during transit checks, that you must check the oil level and the filter
DPI each 150 FH or each time the engine cowls are opened.
On each engine, use the sight glass that is in the vertical position to
do the check of the oil level. If it is below the green band or above
the yellow band, do the oil servicing.
Clogged filter indication is provided by a visual pop out indicator (the
DPI) mounted on the IDG. This indicator is installed opposite the
drive end of the IDG.

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24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

SERVICING - CHECK OF THE OIL LEVEL AND FILTER DPI
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

ELECTRICAL POWER LEVEL 2 (2)
SERVICING (continued)
OPERATIONAL TEST OF THE IDG DISCONNECT AND
RECONNECT FUNCTION

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The IDG will be disconnected in case of:
- oil overheat (high oil out temperature),
- oil pressure drop when not caused by drive under speed.
The amber FAULT legend of the ELECtrical/IDG1 or 2 P/BSW comes
on, the master warning system is triggered.
In this case, the IDG must be disconnected manually. For this, the
PUSH-TO-DISConnect IDG1 (2) safety guarded P/BSW, installed
on the panel 35 VU, must be pushed.
CAUTION: ENGAGE THE IDG DISCONNECT MECHANISM
WITH THE DISCONNECT RESET RING BEFORE
YOU START THE ENGINE. IF NOT, YOU WILL
CAUSE DAMAGE TO THE GEAR TEETH, AT
ENGINE START.
YOU CAN DAMAGE THE DISCONNECT SOLENOID
BECAUSE OF OVERHEATING IF: YOU PUSH THE
IDG DISCONNECT P/BSW FOR MORE THAN 3

SECONDS. THERE MUST BE AT LEAST 60
SECONDS BETWEEN 2 OPERATIONS OF THE
SWITCH.
On the ELEC control panel, push the IDG 1 (2) P/BSW.
On the IDG 1 (2), slowly pull out the disconnect reset ring to the full
limit of travel. If you feel a click while you hold the disconnect reset
ring, this shows that the disconnect function operates correctly. Let
the disconnect reset ring go slowly back to the initial position.

FILLING OF THE IDG WITH OIL OR ADDITION OF
OIL
CAUTION: USE ONLY NEW CANS OF OIL WHEN YOU FILL
THE IDG WITH OIL OR ADD OIL TO THE IDG. THE
CONTAMINATION IN THE OIL RAPID
DETERIORATION OF THE OIL AND WILL
DECREASE THE LIFE OF THE IDG.
Make the thrust reverser unserviceable,
Depressurize the IDG case,
CAUTION: USE ONLY APPROVED TYPES/BRANDS OF
LUBRICANTS. DO NOT MIX TYPES/BRANDS OF
LUBRICANTS.
Fill the IDG with filtered oils at a maximum pressure of 35 PSI (2.4131
bar),
Inspect the oil level before and after the related engine start. Inspect
the oil level after it becomes stable (5 minutes after running),
If the oil level is at or near the top of the green band, oil servicing is
not necessary. If the oil level is below the green band or above the
yellow band, servicing is necessary.

NOTE: The IDG disconnection is irreversible in flight. Reconnection

of the system is then possible only on the ground with
engines shut down.
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24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

SERVICING - OPERATIONAL TEST OF THE IDG DISCONNECT AND RECONNECT FUNCTION & FILLING OF THE IDG WITH OIL OR
ADDITION OF OIL
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

ELECTRICAL POWER LEVEL 2 (2)
SERVICING (continued)

IDG VIDEO

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The video shows the servicing of the IDG.

MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

SERVICING - IDG VIDEO
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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ELECTRICAL POWER LEVEL 2 (2)
MAINTENANCE TIPS

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It must be mentioned here that the most typical reason for IDG failures
are due to over servicing. You must pay particular attention to the level
of the oil in the sight glass.
When servicing, leave the drain hose attached until only a couple of drops
come out.

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24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

MAINTENANCE TIPS
MAINTENANCE COURSE - M35 LINE MECHANICS (V2500-A5/ME) 
24 - ELECTRICAL POWER

ELECTRICAL POWER LEVEL 2 (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

IDG COOLING SYSTEM (3)
GENERAL
The Integrated Drive Generator (IDG) oil cooling system consists of a
self-contained oil circuit and a fuel/oil heat exchanger.

OPERATION PRINCIPLE
A scavenge pump pumps the oil through the oil filter and the fuel/oil heat
exchanger. A charge pump provides regulated oil supply pressure to the
users. The engine fuel flow regulates the IDG oil temperature through
the fuel/oil heat exchanger.

COLD CONDITIONS
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. As the
oil warms up, the cooler bypass valve closes and the oil flows through
the fuel/oil heat exchanger.

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FILTER CLOGGED
A clogged filter indication is provided by a local visual Delta Pressure
pop-out Indicator (DPI). In case of clogging indication, a DPI reset can
be done in some conditions and associated with maintenance procedures.

When the filter is clogged, the relief valve opens.

TEMPERATURE AND PRESSURE MONITORING
For overheat detection, oil temperature sensors monitor the temperature
of both input and output oil. A pressure switch operates in the event of
a loss of charge oil pressure.

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24 - ELECTRICAL POWER

IDG COOLING SYSTEM (3)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

GENERAL ... TEMPERATURE AND PRESSURE MONITORING
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IDG COOLING SYSTEM (3)

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IDG MONITORING (2)
TEMPERATURE MONITORING
If an overtemperature is detected at the Integrated Drive Generator (IDG)
outlet, the associated alarms are triggered. If the TEMPerature rises above
147°C, the ELEC ECAM page is automatically displayed through the
advisory mode and the temperature indication flashes. If the temperature
exceeds 180°C, the indication turns from green to amber. Above 185°C,
the MASTER CAUTion and IDG FAULT lights come on, the single
chime is triggered.

TEMPERATURE RISE INDICATION
If the temperature rise indication is over a given limit, a signal is sent to
the Centralized Fault Display Interface Unit (CFDIU) through the Ground
Power Control Unit (GPCU).
A class 2 failure message can be displayed on the MCDU: IDG 1 (2)
HIGH DELTA TEMP.

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PRESSURE MONITORING
In case of loss of charge oil pressure the corresponding indications and
warnings are triggered only when the corresponding engine is running.
The low pressure warning is inhibited, for IDG input speed below 2.000
rpm. The normal input speed range is between 4.500 and 9.120 rpm.

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IDG MONITORING (2)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

TEMPERATURE MONITORING ... PRESSURE MONITORING
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IDG MONITORING (2)

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AC MAIN GENERATION D/O (3)
GENERATOR
The generator is a conventional 3 co-axial component brushless generator,
which consists of:
- a Permanent Magnet Generator (PMG),
- a rotating diode pilot exciter,
- the generator itself.
The generator is driven at a constant speed of 12.000 rpm and cooled by

oil spraying.

GENERATOR CONTROL UNIT SUPPLY
The PMG supplies the exciter field through the Generator Control Relay
(GCR) and the Generator Control Unit (GCU) through a rectifier unit.
The GCU supply from the aircraft network is duplicated (back up supply).
The supply is taken from the DC essential system. The excitation control
and regulation module keeps the voltage at the nominal value at the Point
Of Regulation (POR).

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GENERATOR OPERATION CONTROL
The generator is controlled by the corresponding GENerator P/B. When
pressed in, if the generator speed is high enough, the generator is
energized. If the delivered parameters are correct, thus the Power Ready
Relay (PRR) closed, the Generator Line Contactor (GLC) closes to supply
its network.

NOTE: During the AVIONICS SMOKE procedure, the FAULT light
does not come on when the GEN 1 LINE P/B is set to off.

GENERATOR 1
To avoid complete loss of fuel pumps electrical supply during the smoke
procedure, the GEN 1 LINE P/B is released out to open the line contactor.
Generator 1 is still excited and supplies fuel pumps 1LH and 1RH.

GENERATOR RESET
When the GEN P/B is released out after a fault detection, the GCU is
reset. The GCR and the PRR are reset.

INTERFACES
The GCU interfaces with:
- the ENGINE FIRE P/B. When released-out, the generator is
de-energized,
- both SDACs for ECAM monitoring,
- the Centralized Fault Display Interface Unit (CFDIU) through the
Ground Power Control Unit (GPCU),
- the Full Authority Digital Engine Control (FADEC), which gives the
engine speed information.

GENERATOR MONITORING
The FAULT light comes on when any generator parameter is not correct
or when the GLC is open. The generator failure signal is sent to System
Data Acquisition Concentrator (SDAC) 1 and 2 through the Electrical
Generation Interface Unit (EGIU). When the engine is shut down, the
corresponding GEN FAULT light is on.
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AC MAIN GENERATION D/O (3)

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SINGLE AISLE TECHNICAL TRAINING MANUAL

GENERATOR ... INTERFACES
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AC MAIN GENERATION D/O (3)

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