ATA 24 ELECTRICAL POWER.pdf

8/9/2019 ATA 24 ELECTRICAL POWER.pdf

1/67

ATA 24

Electrical Power

A330/340 24 L3 E

ATA Spec 104 Level 3

A330/A340

AIRBUS


2/67

For training purposes only. Copyright by Lufthansa Technical Training.LTT is the owner of all rights to training documents and trainingsoftware.Any use outside the training measures, especially reproductionand/or copying of training documents and software − also extractsthereof −in any format all (photocopying, using electronic systemsor with the aid of other methods) is prohibited.Passing on training material and training software to third partiesfor the purpose of reproduction and/or copying is prohibited without

the express written consent of LTT.Copyright endorsements, trademarks or brands may not be re-moved.A tape or video recording of training courses or similar services isonly permissible with the written consent of LTT.In other respects, legal requirements, especially under copyrightand criminal law, apply.

Lufthansa TechnicalTrainingDept HAM USLufthansa Base HamburgWeg beim Jäger 193

22335 HamburgGermany

Tel: +49 (0)40 5070 2520Fax: +49 (0)40 5070 4746E-Mail: [email protected]


3/67

L u

f t h a n s a T e c h n i c a l T r a i n i n g

F o r T r a i n i n g P u r p o s e s O

n l y

ELECTRICAL POWER A330-200/300 A340-200/300 A340-500/600

24−00

Page: 1FRA US/T2 ToR Feb 05

ATA 24 ELECTRICAL POWER


4/67

L u



n l y

ELECTRICAL POWERGENERAL

A330-200/300 A340-200/300 A340-500/600ENHANCED

24−00

Page: 2FRA US/T-2 ToR Feb 05

ELECTRICAL POWER SYSTEM PRESENTATION

ELECTRICAL GENERATION

The AC main power sources are:

the two Integrated Drive Generator (IDGs)(A330),

the four Integrated Drive Generator (IDGs)(A340),

the APU generator,

and 2 EXTernal PoWeR sources.

The AC emergency power sources are:

the EMERgency GENerator,

and the STATic INVerter supplied by the DC system.

The DC main power sources are the 3 Transformer Rectifiers (TRs) suppliedby the AC system.

The DC emergency power sources are the 2 batteries.

A third APU BATtery associated with the APU T.R. is only used to start theAPU.


5/67

L u



n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−00


(

( )onlyA340

Figure 1 System Presentation


6/67

L u



n l y


A330-200/300ENHANCED

24−00


AC MAIN GENERATION

The main generators supply the network trough a Generator Line Contactor(GLC).

The APU generator delivers power trough an APU Generator Line Contactor(AGLC).

Each external power are connected trough External Power Contactor (EPC).

AC TRANSFER

The transfer circuit comprises two Bus Tie Contactors (BTCs) and a SystemIsolation Contactor (SIC). These contactors operate automatically in order tofeed the main busbars in different configurations following the entry source.

AC EMERGENCY GENERATION

The EMERgency GENerator, also called Constant Speed Motor/Generator(CSM/G) is used in emergency configuration; when the main generators andthe APU are lost for example. It operates from the green hydraulic system.

The STATic INVerter is supplied from battery 1 and 2, and automatically sup-plies the AC ESSential BUS if no other sources is available.

AC ESSENTIAL SUPPLY

AC ESS buses supply logic

The AC ESS network supplies the most important and safety critical circuits ofthe A/C. In normal configuration, the ESS bus is supplied from AC BUS 1. IfAC BUS 1 fails, there is an automatic switching of the supply to AC BUS 2. Thepilot can also perform this switching manually. Other possible sources of supplyfor the AC ESS buses are the EMER GEN, or the STAT INV (only for AC ESSbus).

AC GENERATION PROPERTIES

GEN, APU GEN, EXT PWR, EMER GEN, STAT INV properties

This table gives the properties of the different AC power sources.

Note that the static inverter is a single phase power source.


7/67

L u



n l y



24−00


Figure 2 AC Main Generation


8/67

L u



n l y


A340−200/300 A340−500/600ENHANCED

24−00


AC MAIN GENERATION

The AC main system is composed of 4 buses.

The main generators supply the network trough a Generator Line Contactor(GLC).

The APU generator delivers power trough an APU Generator Line Contactor(AGLC).

Each external power are connected trough External Power Contactor (EPC).

AC TRANSFER

The transfer circuit comprises four Bus Tie Contactors (BTCs) and a SystemIsolation Contactor (SIC). These contactors operate automatically in order tofeed the main busbars in different configurations following the entry source.

AC EMERGENCY GENERATION

The EMERgency GENerator, also called Constant Speed Motor/Generator(CSM/G) is used in emergency configuration; when the main generators and

the APU are lost for example. It operates from the green hydraulic system.The STATic INVerter is supplied from battery 1 and 2, and automatically sup-plies the AC ESSential BUS if no other sources is available.

AC ESSENTIAL SUPPLY

AC ESS buses supply logic

The AC ESS network supplies the most important and safety critical circuits ofthe A/C. In normal configuration, the ESS bus is supplied from AC BUS 1−1. IfAC BUS 1−1 fails, there is an automatic switching of the supply to AC BUS2−4. The pilot can also perform this switching manually. Other possible sourcesof supply for the AC ESS buses are the EMER GEN, or the STAT INV (only forAC ESS bus).

AC GENERATION PROPERTIES

GEN, APU GEN, EXT PWR, EMER GEN, STAT INV properties

This table gives the properties of the different AC power sources.

Note that the static inverter is a single phase power source.


9/67

L u



n l y


A340−200/300 A340−500/600ENHANCED

24−00




10/67

L u f t h a n s a T e c h n i c a l T r a i n i n g


n l y


A330−200/300ENHANCED

24−00

Page: 8FRA US/T-2 ToR Dec 03

DC MAIN GENERATION

The DC main system is composed of 3 buses:

DC BUS 1 supplied from AC BUS 1 via TR 1,

DC BUS 2 supplied from AC BUS 2 via TR 2,

DC BAT BUS, normally supplied from DC BUS 1.

If the AC BUS 1 is no longer supplied, AC BUS 2 supplies the DC BAT BUSfrom DC BUS 2.

The DC ESSential BUS is normally supplied from AC BUS1 via the ESSentialTR.

If AC BUS 1 is not supplied, AC BUS 2 will supply the DC ESS BUS.

If no other source is available, BATtery 1 and 2 supply the DC ESSential BUS.Notice that the HOT BUSes are always supplied from the BATteries.

All 4 TRs are the same and deliver 28 VDC.

TR 1 and TR 2 are rated at 200 A.

ESSential TR and APU TR are rated at 100 A.

All BATteries are 24 V, 40 Ah.


11/67



n l y


A330−200/300ENHANCED

24−00

Page: 9FRA US/T-2 ToR Dec 03

Figure 4 DC Generation


12/67



n l y


A340−200/300 A340−500/600ENHANCED

24−00


DC MAIN GENERATION

The DC main system is composed of 3 buses:

DC BUS 1 supplied from AC BUS 1−2 via TR 1,

DC BUS 2 supplied from AC BUS 2−3 via TR 2,

DC BAT BUS, normally supplied from DC BUS 1.

If the AC BUS 1−2 is no longer supplied, AC BUS 2−3 supplies the DC BATBUS from DC BUS 2.

The DC ESSential BUS is normally supplied from AC BUS1−1 via the ESSen-tial TR.

If AC BUS 1−1 is not supplied, AC BUS 2−4 will supply the DC ESS BUS.

If no other source is available, BATtery 1 and 2 supply the DC ESSential BUS.Notice that the HOT BUSes are always supplied from the BATteries.

All 4 TRs are the same and deliver 28 VDC.

TR 1 and TR 2 are rated at 200 A.

ESSential TR and APU TR are rated at 100 A.

All BATteries are 24 V, 40 Ah (A340−200/300)

All BATteries are 24 V, 50 Ah (A340−500/600)


13/67



n l y


A340−200/300 A340−500/600ENHANCED

24−00


Figure 5 DC Generation


14/67



n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−00

Page: 12FRA US/T-2 ToR Jan 05

CONTROL AND MANAGEMENT

In order to control, protect and manage all power sources and the electricalnetwork, several computers are involved in the electrical system.

GENERATOR CONTROL UNIT (GCU)Two identical Generator Control Units (GCUs) control and protect the enginegenerators.

GROUND AND AUXILIARY POWER CONTROL UNIT (GAPCU)

The Ground and Auxiliary Power Control Unit (GAPCU) is in charge of control-ling and protecting the two external power sources A and B and the APU Gen-erator. It is also an interface for the GCUs BITE and a frequency reference forthe NBPT.

ELECTRICAL CONTACTOR MANAGEMENT UNIT (ECMU)

Two Electrical Contactor Management Units (ECMUs) control the main AC andDC electrical power contactors, giving priorities and enabling reconfiguration of

the main power supply sources. The ECMUs also control and monitor the gal-ley shedding configuration, and enable NBPT function between the availablesources.

ELECTRICAL LOAD MANAGEMENT UNIT (ELMU) (A340−500/600 ONLY)

One Electrical Load Management Unit (ELMU) enables reduction ofthe aircraft power consumption by shedding momentarily certain lessimportant power users; for example, the Cabin loads.

CONSTANT SPEED MOTOR / GENERATOR GCU (CSM/G GCU)

One CSM/G GCU (CSM/G GCU)controls the CSM/G also called EMER GEN.

BATTERY CHARGE LIMITER (BCL)

Three identical and interchangeable Battery Charge Limiters (BCLs) controland protect the batteries

CIRCUIT BREAKER MONITORING UNIT (CBMU)

One Circuit Breaker Monitoring Unit (CBMU) is installed in order to give thestatus of the Circuit breakers on the ECAM.


15/67

L

u f t h a n s a T e c h n i c a l T r a i n i n g


n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−00


A340−500/600ONLY

A340 SHOWN

Figure 6 System Computers


16/67

L



n l y

ELECTRICAL POWERAC GENERATION

A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


MAIN AC GENERATION DESCRIPTION

ELECTRICAL PANEL

The overhead ELEC panel is used to control and monitor several functions.

There are several P/Bs which will be explained in this module such as:

The Integrated Drive Generator (IDG) P/B, for IDG disconnection,

The GEN P/B, for connection or disconnection of generator and resetting ofthe Generator Control Unit (GCU),

The BUS TIE P/B, for isolation of the network.

INTEGRATED DRIVE GENERATOR

Identical IDGs are used to supply the main AC network.

Each IDG is a two pole high speed (24000 RPM) brushless spray oil cooled

unit.

It comprises, in a common housing:

The drive part, with the monitoring and control items,

The generator part, which consists of a Permanent Magnetic

Generator (PMG), an exciter generator with rotating diodes and a main genera-

tor.

The Constant Speed Drive (CSD) of the IDG converts the variable input speed(4900 to 9120 RPM), provided by the engine gearbox, into the constant outputspeed (24000 RPM).

GENERATOR CONTROL UNIT

Each IDG is controlled and monitored by its own GCU. All the GCUs are fullyidentical and interchangeable.

IDG operation is not possible with a faulty GCU.

The GCU fulfills the following main functions:

control and protection

regulation of the generator voltage

regulation of the generator frequency

No Break Power Transfer (NBPT) in conjunction with the Electrical Contac-tor Management Unit (ECMU)

interface with the System Data Acquisition Concentrators (SDACs)

interface with the Full Authority digital Engine Control (FADEC) for enginespeed

interface with the Central Maintenance System (CMS) via the Ground andAuxiliary Power Control Unit (GAPCU)

A special pin programming provides the GCU with the following information:

the aircraft type

the GCU identification/installation position

the current limit for voltage regulation

During normal operation, each GCU allows IDG parameters, such as voltageand frequency, to be regulated. It also monitors the main generation systemand provides operational information to the cockpit crew. The GCU also pro-tects the IDG against abnormal conditions.


17/67

L


F o r T r a i n i n g P u r p o s e s O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20




18/67

L




A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


DESCRIPTION (CONT.)

GENERATOR LINE CONTACTOR

The Generator Line Contactors (GLCs) allows connection of the generator tothe corresponding AC BUSbar.

Each GLC is controlled and monitored by the associated GCU and ECMU.

FEEDER LINE

A special 3 phase generator feeder cable and neutral (part of the engine) con-nects the generator terminal block to a terminal block located on the upper en-gine structure (disconnection for engine change). The neutral line is also con-nected to the engine structure.

Another terminal block, located in the pylon, splits each phase into two feedercables, sent through the wing leading edges and the cargo compartment torack 710 VU in the avionics compartment. They are connected to the GLC afterhaving passed through a 6−hole Current Transformer (CT).

The Feeder line and the generator are protected by the differential and opencable protection circuits.

TRANSFER CIRCUIT

The transfer circuit consists of the transfer line, the Bus Tie Contactors (BTCs)and the System Isolation Contactor (SIC). This circuit enables the powersources (GEN‘s, APU GEN and the 2 external powers) to supply the entire orhalf of the network according to the priority logic and the NBPT rules.

ECMU

The GLCs are under control of the related GCU and ECMU. If all parametersare correct, the GLC connects the generator to its own busbar.

The BTCs and the SIC are automatically controlled by the ECMUs, enabling

the whole electrical network to be supplied.The ECMUs receive relative IDG information via the GCUs.

Each ECMU monitors the status of its own side contactors (ECMU 1 for righthand side and ECMU 2 for left hand side) and ensures the opening or closingaccording to the priority logic and the NBPT operation (on ground only).


19/67

L




A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20




20/67

L




A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


INTEGRATED DRIVE GENERATOR OPERATION

IDG CONTROL P/B

The IDG can be manually disconnected with the IDG P/B, located on the over-head ELEC panel.

When the engine is running, above the set point value (4900 RPM), action onthis P/B immediately disconnects the IDG.

With engine stopped, the IDG cannot be manually disconnected. An under-speed condition generated by the GCU inhibits the disconnection.

GEN CONTROL P/B

The GEN P/B on the overhead ELEC panel is used to connect or disconnectthe generator and to reset the GCU. When the P/B is released out (off posi-tion), the OFF/R legend appears, the generator field is de−energized and theline contactor is open.

When the P/B is pressed in (on position), the generator is put on line as soonas the electrical parameters are within the limits.

The FAULT legend comes on (in on position only) in the following cases: The related engine is shutdown

During operation with any incorrect parameter

With correct parameters but the GLC stays open due to failure.

The FAULT information is sent to ECAM.

After fault detection, setting the GEN P/B to off and then to on resets the GCU.

GENERATOR SPEED CONTROL

The generator speed is controlled by a system composed of a servovalve inthe IDG and an electronic control circuit in the GCU

The electronic control circuit controls the servo−valve, which in turn controlsthe CSD speed variation to keep the generator at a constant frequency.

The GCU performs the outspeed control of the IDG whenever several condi-tions are met:

The GCU is powered up,

Engine input speed to the IDG is between 4900 and 9120 RPM,

No failure is present to trip the servo valve control circuit.


21/67

L




A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


Figure 9 IDG Operation


22/67

L


F o r T r a i n i n g P u r p o s e s

O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


IDG OIL SYSTEM

The IDG oil is used for IDG cooling, lubrication and to operate the CSD.

The IDG oil system also cools and lubricates the CSD and the generator partsof the IDG.

IDG OIL PRESSURE

The oil pressure is monitored by a Low Oil Pressure (LOP) switch located inthe IDG charge oil circuit.

The LOP switch provides a signal to the GCU when IDG charge oil pressure isless than 140 PSI.

In LOP condition, not caused by under−speed, the IDG P/B FAULT legendcomes on amber and an ECAM warning is triggered.

The Differential Pressure Indicator (DPI) indicates a clogged filter condition. Anassociated pop−out indicator located on the IDG filter housing shows when thefilter element requires replacement

The IDG scavenge oil filter is fitted with a DPI. The switch is located across thescavenge filter

In the case of a clogged filter, the DPI sends a signal to the GCU, which, inturn, sends a status message to the ECAM.

A visual check of the pop−out is required.

If the DPI is popped out, both filters (inlet and outlet) and oil must be replacedaccording to AMM procedures.

The DPI device is automatically inhibited during cold oil running conditions (un-derspeed), due to high oil viscosity.

IDG OIL LEVEL

The GCU includes a Remote Oil Level Sensor (ROLS) function which enableslow IDG oil level to be detected.

The ROLS sensor is located in the IDG.

Six to eight minutes after engine shutdown, the GCU supplies the sensor for 30seconds for an oil interrogation sequence.

In the case of oil low level detection, the GCU sends a status message to theECAM.

A visual check of the oil level sight glass is required.

If the oil level is high in the yellow or in the red area, oil servicing must be per-formed.

IDG OIL TEMPERATURE

There are two oil temperature sensors in the IDG:

One sensor on the IDG oil inlet port,

One sensor on the IDG oil outlet port.

These sensors allow the IDG oil temperature to be monitored.

The GCU transmits the oil outlet temperature to the System Display (SD) elec-trical page enabling high oil temperature detection. The SD also indicates theIDG oil differential temperature (rise temperature).

When the outlet oil temperature reaches 152°C, an advisory mode is sent tothe ECAM.

If oil overheat detection is detected (Temperature > 185°C), the warnings areprovided to the ECAM and call for IDG manual disconnection (BITE message:OIL OVHT).

There is no automatic thermal disconnection mechanism is fitted to the IDG(A330−200/300 only).

An automatic thermal disconnection mechanism is fitted to the IDG

(A340−500/600 only).If an IDG manual disconnection is not performed and the oil temperaturereaches 200°C, the automatic thermal disconnection takes place. A BITE mes-sage (THERMAL DISCONNECT) is sent to ECAM.

Over 200°C and IDG not disconnected by the thermal disconnection, the BITEmessage (THERMAL DISCONNECT FAILURE) is sent to ECAM.The engine must then be shutdown.

If the IDG oil temperature is above 200°C and no thermal disconnection oc-curs, a thermal disconnection fault message will be displayed.

In the EEPGS, failure of the IDG oil−out temperature sensor is a class 3 fault,and no flight deck effects are presented. The GCU will automatically providethe IDG oil−in temperature (plus a nominal temperature offset) and display this

„calculated„ temperature value as the oil−out temperature on the ECAM ACELEC page.

Recognition of an IDG cooler fault and IDG high delta temperature fault is in-hibited if the oil−out temperature bulb has failed. IDG oil overtemperatureprotection will continue to be active (using the „calculated“ oil−outtemperature as the monitored parameter).

g


23/67

L



O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


Figure 10 IDG Operation

g


24/67

L



O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


IDG DISCONNECTION MECHANISM

SPEED CONTROL LOOP

The loop is composed of a servo−valve in the IDG and an electronic controlcircuit in the GCU which includes the Servo−Valve Relay (SVR).

The electronic control circuit monitors the generator PMG frequency andcompares it with a GCU internal frequency reference.

The difference between these two frequencies creates an error signal. This sig-nal is used to control the servo−valve oil via the SVR to regulate the outputspeed.

The servo−valve maintains the desired generator frequency (400 Hz) by send-ing more or less oil to a variable hydraulic unit according to the error signal.

The variable hydraulic unit acts on a rotary part allowing the output speed ofthe CSD to be adjusted.

Notice that during NBPT condition, the PMG frequency is compared with therelative frequency of the source connected in parallel.

IDG DISCONNECTION MECHANISMWhen the engine is running (input speed above 4900 RPM), the FAULT legendof the P/B comes on if the IDG oil pressure is less than 140 PSI or if the IDGoil outlet temperature is above 185 C.

In both cases, the IDG must immediately be disconnected via the IDG P/B.

When the IDG P/B is pressed, the solenoid control relay is energized and con-nects the 28 VDC to the disconnection solenoid which will open the clutch.

The IDG P/B OFF legend comes on and the FAULT legend goes off. The OFFlegend remains on until the clutch is reset and the engine is running.

IDG reset can only be performed on ground with engine shutdown, by pullingthe reset ring mounted on the IDG casing.

In under−speed condition (input speed below 4900 RPM) it is not possible todisconnect the IDG.

Note that a detected under−speed inhibits the speed related protection circuits(under−frequency and under−voltage).

In case of the oil temperature exceeding 200C, an automatic thermal discon-nection mechanism disconnects the IDG from the engine gearbox(A340−500/600 only).After a thermal disconnection, the IDG must be changed.

The EEPGS IDG does not incorporate an integral switch in the disconnect so-lenoid to provide IDG disconnect status information to the flight deck but theEEPGS GCU does not interface electrically with the disconnect status switch.

The EEPGS GCU senses IDG disconnect status by monitoring IDG disconnectswitch action, and the IDG PMG frequency. The IDG disconnect status isdetermined in GCU software, and an NVM latch is set in the GCU to illuminatethe „OFF“ lamp in the IDG disconnect control switch on panel 235VU

NOTE: The IDG „OFF“ lamp and the „DISC“ icon on the ECAM AC ELEC pagewill only go off after the GCU senses that IDG input speed is above 2000 rpmat the next engine start.

gELECTRICAL POWER A330 200/300 A340 200/300 A340 500/600


25/67



O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


Figure 11 IDG Cooling and Disconnect System

n g

ELECTRICAL POWER A330 200/300 A340 200/300 A340 500/600


26/67

L u f t h a n s a T e c h n i c a l T r a i n i n


O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


IDG OIL COOLING SYSTEM

OIL COOLING

Three types of oil cooling system exist:

Oil cooling via Air Cooled / Oil Cooler (ACOC) system,

Oil cooling via Engine Fuel / Oil cooler system and Air / Oil heat Exchanger(AOHE),

RR Engines Oil cooling via Engine Fuel / Oil cooler only.

System available for A340−500/600 (RR engines) and A330 (RR engines).The ACOC system is available for A/C equipped with Rolls Royce engines. TheACOC is composed of a heat exchanger matrix and a duct.

Oil lines connectionThe heat exchanger is connected to the IDG oil system by two oil connections(in and out). The oil flows through the matrix and distributes the heat to the ma-trix fins.

If the oil is cold and does not flow easily through the matrix, a Pressure Relief

Valve (PRV) will open. This will let the oil flow directly from the inlet connectionto the outlet connection and back to the source.When the oil temperature increases, the PRV closes and the oil flows againthrough the matrix.

On A340−500/600 only:

To control the airflow through the heat exchanger the EEC receives the IDG oiltemperature via a dedicated thermocouple. This information is used to control apneumatic actuator which drives a butterfly valve to regulate the flow of cold airthrough the heat exchanger. The actuator uses HP3 air.

PW & GE Engines Fuel / Oil Cooler and Air / Oil Heat Exchanger

System available for:

A330 (PW & GE engines).

A330 A/C equipped with Pratt & Whitney or General Electrics use an AOHEand an Engine Fuel / Oil Cooler for IDG oil cooling.

Directly by Fan air (during high eng. power time: take−off, climb, cruise), or by2.5 bleed cooling air (during low eng. power time: gnd idle, taxi, idle descent)IDG oil T < 105 CThe IDG oil outlet is cooled via the AOHE by fan air during hign engine powertime (take−off, climb, cruise) or by 2.5 bleed cooling air during low enginepower time (ground idle, taxi, idle descent).

AOHE

The AOHE valve, regulted by the Electronic Engine Control (EEC), maintains

an IDG oil temperature less than 105 C.Engine Fuel / Oil CoolerThen IDG oil flows in the Engine Fuel / Oil Cooler to keep an IDG oil inlet tem-perature between 70C and 105C. Notice that the AOHE valve is springloaded in case of no information from ECC to allow the oil cooling.

CFM Engines Fuel / Oil Cooler

System available for:

A340 with CFM engines.

A340 equipped with CFM engines use only an Engine Fuel / Oil Cooler for IDGoil cooling. The IDG outlet oil flows directly in Engine Fuel / Oil Cooler to keepan IDG inlet oil temperature between 70 C and 105 C.

n g

ELECTRICAL POWER A330 200/300 A340 200/300 A340 500/600


27/67



O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


TO EEC(A340−500/600 only)

Figure 12 IDG Cooling System

n g



28/67



O n l y


A330-200/300 A340-200/300 A340-500/600ENHANCED

24−20


MAIN AC ELECTRICAL SYSTEM OPERATION

CONTROL AND PROTECTION

The GCU controls the connection and disconnection of the IDG to and from theaircraft electrical system.

These controls are mainly performed by means of 3 internal relays: the Generator Control Relay (GCR) controls the generator excitation,

the Power Ready Relay (PRR) controls the GLC and the NBPT

the SVR controls the generator rotor speed by means of the servovalve.

If a protection function is triggered, the GCR, the PRR and, in some cases, theSVR are de−energized.

VOLTAGE REGULATION

The GCU monitors the Point Of Regulation (POR) in order to keep the voltageat nominal value (115 VAC) at this point.

The POR is located at the end of the generator feeder, upstream of the GLC.

The voltage regulation is achieved by regulating the current through the exciterfield.

The output from the PMG is connected via the GCR to the excitation and regu-lation control module, where it is converted into DC voltage and applied to theexciter field.

The voltage frequency regulation module senses the average of the threephases at the POR and compares it against a reference voltage.

If a difference exists, the voltage regulator adjusts the exciter field current asneeded to keep a constant voltage at the POR.

UNDERSPEED

The Engine Interface and Vibration Monitoring Unit (EIVMU) provides enginespeed information to the GCU for underspeed setpoint, control and protection

and BITE functions. The EIVMU is a part of the FADECWhen the engine speed falls below the underspeed threshold (4900RPM), thePRR trips and the excitation is biased off due to underfrequency at PMG output(


29/67

L u f t h a n s a T e c h n i c a l T r a i n i


O n l y


A330 200/300 A340 200/300 A340 500/600ENHANCED

24−20


Figure 13 Control and Protection

i n g



30/67

L u f t h a n s a T e c h n i c a l T r a i n i


O n l y

C C OAC GENERATION

330 00/300 3 0 00/300 3 0 500/600ENHANCED

24−20


DIFFERENTIAL PROTECTION

The Differential Protection (DP) is based on the comparison of each phase ofthe 6 hole CTs (on line) and the 3 CTs windings in the IDG.

If the difference of current is above 50 +/− 10 A for at least 60 milliseconds, thePRR and GCR are tripped.

The DP circuit reset is done via the GEN P/B and this protection can be resettwice.

After 2 reset attempts, the GCU must be powered down (cold start) to reset theprotection latch−in software.

OVERLOAD AND OVERCURRENT

The IDG CTs provide current sensing information to the GCU. In case of over-load or over−current, the corresponding GCU protection circuits are triggered.

If the overload is still present 10 seconds after this initialization, the GCU onlysends a signal to the ECMU to shed the corresponding galley.

No tripping occurs.

If the auto shedding is performed, no warning is triggered.

If the shedding is not effective, the ECAM is triggered and the FAULT legendon the GALLEY P/B comes on.

The crew has to press the GALLEY P/B to reduce generator load.

If an overcurrent is detected and, after the inverted protection time delay, theBTC is locked in OPEN position.

If the fault persists, the generator is de−energized (via the GCR) and the GLCis opened (via the PRR)

The ELMU is connected to the GCU‘s.

Data from the GCU‘s is used by the ELMU to get the configuration of the elec-trical network.

INADVERTENT PARALLEL TRIP

The power supply logic to each AC main bus bar is established through theECMU control system.

Furthermore, the NBPT allows two AC sources to be connected during thetransfer phase.

After transfer completion, a special protection in the ECMU and GCU (lock outcircuit) avoids an Inadvertent Paralleling Trip (IPT) condition.

FIRE PROTECTION

In case of engine fire, if the related fire switch is released out, a 28 VDC signalis sent to the corresponding GCU which shuts down its IDG. This signal is notlatched, thus no reset is required.

i n g



31/67

L u f t h a n s a T e c h n i c a l T r a i n


O n l y

AC GENERATION ENHANCED

24−20


Figure 14 Control and Protection

n i n g



32/67



O n l y

AUXILARY / EXTERNAL POWER ENHANCED

24−40


GROUND AND AUXILIARY POWER CONTROL UNIT (GAPCU) DESCRIPTION

The GAPCU controls both the APU generator channel and external power Aand B system contactors and relays.

These contactors and relays (AGLC, EPCs, System Isolation Contactor (SIC),

Power Ready Relay (PRR), External Power Ready Relay (EPRR) can only beclosed when the correct conditions exist. They are opened manually or auto-matically (control and protection).

In addition, the GAPCU performs:

A back−up control for external power A only,

BITE analysis,

communication functions between GCUs, ECMUs, ECB, Centralized Main-tenance Computers (CMCs), Landing Gear Control and Interface Unit 1(LGCIU 1),

interface with ECAM (via the System Data Acquisition Concentrators(SDACs), APU, AGLC.

POWER SUPPLYIn normal operation, the GAPCU internal power supply module can be suppliedby:

The APU Permanent Magnetic Generator (PMG) via the APU (TransformerRectifier) TR,

the EXT PWR A and B via the TRs 1and 2.

If a total power supply failure occurs (loss of APU GEN and EXT PWR A andB), the Battery Bus bar 301 PP (DC BAT BUS) supplies the GAPCU via circuitbreaker 204XG. This safety is the GAPCU back−up supply.

COMMON FUNCTION

The GAPCU communicates with the GCUs , and the CMCs.

The GAPCU communicates with each of the GCUs via MIL 1553 links.The GAPCU always initiates the transfer of information from the GCUs, andcommunicates during 2 transmission modes: normal and interactive mode.

In normal mode (FLIGHT), the GAPCU periodically interrogates each GCU forchannel and fault status.

The GAPCU also receives the GCU Line Replaceable Unit (LRU) identificationand pin programming information (A/C and engine types).

In interactive mode (only on ground when requested from CMCs), the normalmode may be interrupted. The GAPCU will request a self−test of each of theGCUs and will perform its own.

The GAPCU is a type 1 computer. It communicates with the two CMCs via twoARINC 429 links.

During the normal mode of transmission, the GAPCU will continually send itsown fault data and that of the four GCUs to the CMCs.

Access to the interactive menu is gained through the Electrical Power Genera-tion System (EPGS) system page, displayed on the Multipurpose Control andDisplay Unit (MCDU) System/Report page.

Upon request from the CMC, the GAPCU stops the normal mode of transmis-sion and enters the interactive mode to follow CMC commands.

Then, the GAPCU transmits the EPGS main menu.

The GAPCU interfaces with two SDACs via an ARINC 429 link.

During all operation modes, the GAPCU will continually transmit data to the

SDACs. The SDACs will use this data to provide information and warnings tothe ECAM.

The GAPCU receives an air/ground mode signal from LGCIU1. It is used forthe ground/flight status.

Due to NBPT reasons, when the aircraft is on ground, the APU GEN has prior-ity over the EXT PWR B. Once the APU generator is connected, phase A issent to the Frequency Reference Unit (FRU).

The FRU signal is sent to other GCUs and serves as a reference for furtherNBPTs.

If the APU GEN is in overload condition, the GAPCU informs the ECMU whichsheds the GALLEY and relays the information to the cockpit.

n i n g



33/67



O n l y


24−40


Figure 15 GAPCU

n i n g

ELECTRICAL POWERAUXILARY / EXTERNAL POWER

A330-200/300 A340-200/300 A340-500/600ENHANCED


34/67

L u f t h a n s a T e c h n i c a l T r a i


O n l y


24−40


APU GEN CONTROL FUNCTIONS

The GAPCU also controls, monitors and protects the APU generator supply tothe network.

It ensures the following main functions:

Control of the field excitation through the Generator Control Relay (GCR),

Voltage regulation Control of the AGLC through the PRR in conjunction with the ECMU1,

Control and protection of the APU generator and the network

APU ECB ensures the speed regulation. At 95 % RPM, the ECB provides anAPU ready signal to the control part of the GAPCU.

AGLC CONTROL AND MONITORING

The AGLC connects the APU GEN to the Transfer Circuit.

It is controlled and monitored by the GAPCU and the ECMU 1.

The position of the AGLC is monitored by the FAULT legend on the APU GENP/B switch.

EXT PWR CONTROL FUNCTIONSThe GAPCU controls and monitors EXT PWR contactors and relays. WhenEXT PWR A and/or B are connected, the GAPCU performs the following func-tions:

Monitoring,

interlock function,

EPC control,

protection function,

FRU function for NBPT,

BITE function,

communication and interface.

The diagram shows the connection for External Power B. MONITORINGThe GAPCU permanently monitors the quality of the delivered ground power.

At least one faulty parameter automatically disconnects the ground power fromthe transfer line (EPRR and EPC open).

The interlock system is also activated (Interlock Monitoring Relay (IMR) open)and the GPU shuts down. The IMR enables a holding supply to be connectedto the GPU line contactor.

It is not possible to connect a faulty power source to the network.

INTERLOCK

The conditions for the IMR to be closed are:

The 28 VDC control voltage from the GPU is within accepted limits (


35/67

L u f t h a n s a T e c h n i c a l T r a i


O n l y


24−40


Figure 16 GAPCU

a i n i n g


A330-200/300 A340-200/300 A340-500/600ENHANCED


36/67

L u f t h a n s a T e c h n i c a l T r a


O n l y


24−40


PROTECTION

The GAPCU has to be permanently powered to allow APU or EXTERNALPOWER sources to be connected to the aircraft electrical network.

The BATTERY HOT BUS will ensure the necessary supply to the GAPCU,should a total GAPCU power supply failure occur.

OVERVOLTAGE:Overvoltage (OV) protection is accomplished by monitoring the highest phaseat POR.

An OV condition exists when the highest phase voltage exceeds 130+/−1,5VAC for at least 50 ms.

After an inverse time delay, the IMR and EPRR are tripped.

UNDERVOLTAGE:

Undervoltage (UV) is sensed in the same way as overvoltage.

An undervoltage condition exists when the lowest phase voltage is less than101.5+/−1,5 VAC.

After a 4,5 second time delay max, the EPRR and the IMR are tripped.

OVERLOAD:

The internal CT senses the overload.

An Overload condition exists when the current is greater than 260+ − 15 A onany phase for 10 seconds max.

The galley−shed relay sends a signal to the ECMUs,the ELMUs and to the gal-ley pushbutton switch.

The ECMUs and/or ELMUs reply by shedding loads, depending on the supplyconfiguration faults.

If the overload condition persists for an additional 2 seconds, after the loadshedding action by the ECMUs/ELMUs (galley switch FAULT legend on), the

ECAM warnings are triggered and the message EXT PWR A (or B) OVER-LOAD appears.

All galley loads must be shed by setting the galley P/B to OFF. The

message GALLEY OFF appears.

If after galley shedding an overload is still detected, the overcurrent protectionwill be triggered after an inverse time delay: the IMR and EPRR are tripped.

OVERCURRENT:

This protection function is only available for EXT PWR A.

The internal CT senses the overcurrent (OC).

An overcurrent condition exists when the current on any one phase exceeds277 A.

Once an overcurrent situation is sensed, the GAPCU relays the information tothe ECMU as network status information.

BACK-UP FUNCTION

The GAPCU has a BACK UP module which contain a simplify software. In thecase of the GAPCU main operating software fails, BACK UP module operateson the EXT PWR A board in order to get EXT PWR A available. The BACK UPmodule is, in this case, supplied by the HOT BUS.

LGCIU1 indicates to the GAPCU that the aircraft is on ground and the shockabsorbers are compressed.

Backup supply through EPA in case of GAPCU microprocessor failure.

In case of microprocessor failure, the GAPCU is still able to control a ground

cart connected to the External Power A receptacle.In this case the protections insured by the GAPCU are:

PHASE SEQUENCE

OVERVOLTAGE

UNDERVOLTAGE

OVERFREQUENCY

UNDERFREQUENCY

OVERCURRENT

The galley shed is commanded. All the indicators are working except the dis-play on the ECAM.

BITE is not operative.

a i n i n g


A330-200/300 A340-200/300 A340-500/600ENHANCED


37/67



O n l y


24−40


Figure 17 GAPCU

a i n i n g

ELECTRICAL POWEREXTERNAL POWER

A330-200/300 A340-200/300 A340-500/600ENHANCED


38/67



EXTERNAL POWER ENHANCED

24−40


EXTERNAL POWER

NORMAL OPERATION

The GAPCU controls the electrical connection or disconnection of the externalA and B GPU.

This control is provided by two internal relays: The IMR,

the EPRR.

The IMR, when energized, connects a holding supply to the GPU:

When the external DC input voltage is lower than 42 VDC,

and either the external power A (B) channel fault signal is absent,

or the Analog/Digital (A/D) fault signal is present.

The EPRR is energized when the GPU is properly connected and all parame-ters are correct (no protection functions triggered).

As soon as the ground power unit A (B) is connected, the GAPCU analyzes thevoltage delivered to the external power receptacle. If all parameters are cor-

rect, the GAPCU triggers the following: Illumination of the green AVAIL legend of the EXT A (B) pushbutton

switches, located in the overhead ELEC panel,

illumination of the amber EXT PWR A (B) AVAIL indicator and

the white EXT PWR A (B) NOT IN USE indicator, located in the externalpower receptacle housing, as long as no EXT PWR is connected to the air-craft network (EXT PWR available but not in use).

A light test function on the EXT PWR receptacle panel is used to test the EXTPWR A (B) AVAIL and the EXT PWR A (B) NOT IN USE indicator.

The closed EPRR connects power from the TR via the Positive TemperatureCircuit (PTC) to the busbar 104XG in order to supply the following items:

to the solenoid of EPC A,

to the EXT PWR A NOT IN USE light via contactor 6XX (maintenance busswitch off),

to the EXT PWR A AVAIL light,

to the solenoids of relays 25XG and 9XG for external power switch light andstatus message to ECMUs.

When no anomaly is detected, relay 25XG closes and controls the 5 VAC sup-ply for the AVAIL legend from the internal power supply module

When the EXT PWR P/B switch is pressed, the flip−flop device provides the Dsignal to both ECMUs for NBPT function, and a ground signal to the solenoid ofrelay 9XG.The closed relay 9XG cuts the supply for the AVAIL legend andlights the ON (AUTO) legend via 1LP2.

Then ECMU2 provides a ground signal to close the EPC A, provided the S1signal for NBPT function is valid.

The GPU output is now connected to the transfer circuit.

The EXT PWR NOT IN USE light goes off.

The connection of the ground power to the busbars depends on the supply andtransfer logic.

ABNORMAL OPERATION

An internal feature called Positive Temperature Circuit (PTC) protects bus bar104XG.

This PTC will act as a protective circuit, reacting by heat dissipation to anysensed overcurrent.

In case of protection activation (overcurrent detection), the PTC activates thePTC LED (EXT PWR A only) and de−energizes busbar 104XG. The function isself−reset when the over current condition no longer exists.

In the event of total GAPCU internal failure, with total loss of the control andprotections, a back−up control module ensures the following basic functions,while the aircraft is on ground and EXT PWR A is connected:

Cabin lighting operation for the passenger disembarking,

Ground service systems availability (eg: cargo loading system,...)

The BACK UP module enables the GAPCU to operate in downgraded operat-ing mode.

The BACK UP mode is only valid for EXT PWR A.

a i n i n g


A330-200/300 A340-200/300 A340-500/600ENHANCED


39/67



EXTERNAL POWER24−40


Figure 18 External Power

r a i n i n g

ELECTRICAL POWERTEST

A330-200/300 A340-200/300 A340-500/600ENHANCED


40/67

L u f t h a n s a T e c h n i c a l T r


24−20/40


ELECTRICAL POWER SYSTEM TEST

GENERAL

ELEC AC GENERAL

From the SYSTEM REPORT TEST page, selection of the ELEC: ACGENERATION main menu allows access to the followingsubsystems:

ECMU1/2 (1L/1R)

EPGS (2L)

GCU EMER (3L)

CBMU (4L)

ELMU (5L) (A340−500/600 only)

r a i n i n g

ELECTRICAL POWERTEST

A330-200/300 A340-200/300 A340-500/600ENHANCED


41/67

L u f t h a n s a T e c h n i c a l T r


24−20/40



42/67

L u f t h a n s a T e c h n i c a l T


24−50


ELECTRICAL LOAD MANAGEMENT SYSTEM (ELMS)

GENERAL

The Electrical Load Management System (ELMS) uses a computer, calledElectrical Load Management Unit (ELMU), which monitors the output fromeach AC power source (Intedrated Drive Generator (IDGs), APU GEN, Ground

Power Unit (GPU)). This function is inhibited if the ELMU P/B (235 VU) is set toOFF.

When the ELMU P/B is set to AUTO and the electrical system is supplied, theELMS is passive as long as not required for operation.

As soon as an overload is detected, on any of the AC and DC main bus bars,the ELMU automatically sheds some loads according to the demand.

These loads will be automatically restored to normal operation as soon as theoverload condition has disappeared.The ELMU ensures an optimum use of thepower sources and an optimum availability of the cabin electrical loads.

The ELMU sheds galley and busbars at Remote Control Circuit Breaker(RCCB) level, like the Electrical Contactor Management Unit 1 and 2 (ECMU 1and 2), but also sheds some loads via relays when connected to the busbars.

The ECMUs will be used as a back−up in the case of ELMU failure, but with-downgraded capacity.

The No Break Power Transfer (NBPT) function connects two power sources inparallel to create a transfer phase without cutoff on the busbars on ground only.

DESCRIPTION

The AC main busbars can be supplied:

either by the corresponding generator,

or by another main generator, or the APU generator, or a ground power unit,using the transfer circuit.

In addition to the 115 VAC/400 Hz the busbar 1XP2 and 2XP3 deliver26VAC/400 Hz power through a 115/26 VAC transformer (131XPA and232XPA).

Part of the busbars 1XP1 (sub−busbars 111XP, 113XP, 115XP), 1XP2 (sub−busbar 107XP, 109XP), 2XP3 (sub−busbar 208XP, 218XP, 212XP ) and 2XP4(sub−busbars 210XP, 214XP) are respectively supplied through the RemoteControl Circuit Breakers RCCBs 7XN1, 53XN, 51XN, 59XN, 5XN, 58XN, 60XN,6XN2, 7XN2.

The RCCBs and contactors of the 115XP, 109XP , 107XP, 210XP, 111XP,113XP, 212XP, 208XP, 214XP, 218XP are controlled by the ECMU.

The logic of the ECMUs takes into account the status of the COMMERCIALpushbutton switch.

The ELMU manages the loads connected on these busbars.

As soon as the ELMU is available, the ECMU does not shed these busbars.

The RCCBs of 107XP, 208XP, 218XP are controlled by the ECMUs, the ELMUand the IFE main switch.

Moreover the sub−busbars 111XP, 113XP, 115XP, 212XP, 214XP and 216XPcan be supplied directly from the ground power unit in ground service configu-ration. The 111XP, 113XP, 115XP, 212XP and 214XP are controlled by the EC-MUs.

T r a i n i n g



24 50


43/67


F o r T r a i n i n g P u r p o s e

s O n l y

24−50


Figure 20 Load Management Overview

T r a i n i n g

ELECTRICAL POWERAC DISTRIBUTION


24 50


44/67



s O n l y

24−50

Page: 42FRA US/T-2 ToR Mar 05

CONTACTOR MANAGEMENT DESCRIPTION

Both ECMUs are physically identical and interchangeable. A pin programmingidentifies:

equipment installed on side 1 and on side 2,

installation of options,

type of aircraft.

The ECMUs ensure sub busbars and galley line control according to galley lineand commercial sub busbar control logics, in order to cope with the ELMU op-eration.

The ECMU is a type 2 system computer. It operates as soon as its powered.

POWER SUPPLY

The ECMU power supply depends on the position of the computer inthe avionics bay. The ECMU 1 is supplied by the BAT BUS 301PP, the DC ESSBUS 401PP and the Tie bus 115 VAC. The ECMU 2 is supplied by the BATBUS 303PP, the DC ESS BUS 403PP and the Tie bus 115 VAC.

BAT HOT BUS 701PP and 702PP supply ECMU1 and 2 respectively in thecase of main DC failure and only when the batteries are connected to the air-craft electrical network.

GROUND CONTROL LOGIC

The ECMUs interface with Air Data/ Inertial Reference Unit 1 (ADIRU 1) and 3,and Landing Gear Control and Interface Unit 1 (LGCIU 1).

LGCIU 1 provides the ground/flight information to both ECMUs.

ADIRU 1 provides the ’’less than 50 Kts’’ speed signal to ECMU1 while ADIRU3 provides the same signal to ECMU 2. This information serves for the NBPTfunction when the aircraft is on ground.

BITE

ARINC 429 data buses are connected to the System Data Acquisition Concen-trators (SDACs) for information display on the ECAM, and to the Central Main-tenance Computer (CMC) for BITE information purposes.

Each ECMU continually monitors its inputs, outputs and internal functions todetermine if a failure condition exists. Failure information will be stored in theinternal Non−Volatile Memory (NVM) and also sent to the CMCs.

A self test of the ECMU is automatically performed upon power up and alsoupon request via the Central Maintenance System (CMS). Based on the analy-sis of the ECMU functions, each ECMU provides data to the SDAC to displaythe condition of the power supply and the GALLEY SHED, GALLEY PART

SHED or COMMERCIAL OFF messages on the ELEC ECAM page.

AC CONTACTOR CONTROL

The AC BUS supply is controlled by the ECMUs according the priority supplylogic. They will close or open the various contactors and assign a specificpower source to each AC bus bar.

To control these contactors, the ECMU 1 receives voltage from AC BUS 1−1and 1−2, and the ECMU 2 receives voltage from AC BUS 2− 3 and 2−4. EachECMU also receives the following information:

the NBPT signals (S1 and D signals) and the Power Ready (PR) statusfrom all GCUs,

all AC contactors and BUS TIE P/B status.

NOTE: NOTE THAT WHEN THE BUS TIE P/B IS IN THE OFF POSITION,THE BUS TIE CONTACTORS (BTCS) AND THE SYSTEM ISOLA-TION CONTACTOR (SIC) ARE PERMANENTLY OPEN.

DC CONTACTOR CONTROL

Both ECMUs receive the contactor status data. This is to ensure a correct sup-ply of the various DC bus bars when an AC generation connection occurs, ac-cording to power supply logic.

ECMU 1 receives:

Status of Transformer Rectifier 2 (TR 2) for fault and Over current detection,

28 VDC from TR 1 to supply the DC BUS 1 and 2 (1PC1 and 1PC2) controllogic,

voltage from 101PP (sub−busbar of the DC BUS 1).

ECMU 2 receives:

status of TR 1 for fault and Over current detection,

28 VDC from TR 2 to supply 1PC1 and 1PC2 control logic,

voltage from 206PP (sub−busbar of the DC BUS 2).

A loss of one ECMU does not affect the supply of the main DC buses.

T r a i n i n g



24 50


45/67



s O n l y

24−50


Figure 21 Contactor Management Overview

T r a i n i n g



24−50


46/67

L u f t h a n s a T e c h n i c a l


s O n l y

24−50


REMOTE CONTROL CIRCUIT BREAKER (RCCB)

The RCCB controls and protects the feeder lines.

The RCCB is used to fulfill the following functions:

electrical line protection (tripping function)

electrical load switching (switching function)

The status of the main contacts can be known by visual state indications(OPEN or CLOSE) on the front face of the RCCB and at the level of the com-puters (ELMU and/or ECMUs) by the two internal auxiliary reversing switches.

In the case of tripping (overload or manual trip), a trip signal is transmitted tothe associated ECMU.

The RESET P/B has two stable positions:

When pressed in, electrical control is authorized. On the front face of theRCCB, the visual indication shows the OPEN or CLOSE message in func-tion of the main contact status.

The RESET P/B is released out if there is an overload on the main circuit. Inthis case, the RCCB cannot be electrically controlled. The main contacts are

locked in the OPEN status. The TRIP signal switches from the OPEN to theCLOSE status and a signal is sent to the Circuit Breaker Monitoring Unit(CBMU) for monitoring purposes. On the front face of the RCCB, the visualindication shows the OPEN message. The RESET P/B must be pushed toreactivate the RCCB control.

T r a i n i n g



24−50


47/67



s O n l y

24 50


Figure 22 RCCB

l T r a i n i n g



24−50


48/67



s O n l y

24 50


GALLEY AND COMMERCIAL LOAD CONTROL

The GALLEY and COMMERCIAL load control consists in controlling theRCCBs which shed the galley supply according to the electrical sources avail-able and overloads sensed by the ELMU.

Each ECMU determines the electrical configuration of the aircraft according to

the status data from the ELMU (overload) and the two control switches.The two main relays 2XA1 and 2XA2 are supplied from busbar 601PP, via thetwo control switches in series, and from the corresponding ECMU. These twomain relays control the power to all corresponding RCCBs.

Individual opening or closing of the RCCBs is controlled from the control logicmodule of each ECMU. If one RCCB is open, due to generator overload, themessage GALLEY PART SHED is displayed on the ECAM.

When the GALLEY control P/B is in the OFF position:

the OFF legend comes on,

both main relays are de−energized,

all galleys are OFF,

the ECAM message GALLEY SHED is displayed, the control logic is reset.

When the COMMERCIAL control P/B is in the OFF position:

the OFF legend comes on,

all galleys are OFF,

all service buses are OFF.

The ECAM message COMMERCIAL OFF is displayed.

OPERATION

In case of ELMU set in OFF position or ELMU failure, overload protectionsand shedding are still available from the ECMUs.

In this case the automatic shedding occurs according to the aircraft configura-tion (normal, failed Integrated Drive Generator (IDG), with the APU, etc)

The ECMUs manage the validity of the logics controlling the opening or closure

of each RCCB supplying the galleys:

ECMU 1 (and 2 when 1 fails or inoperative) manage RCCB 1, 2, 3 and 7 viathe relay 2XA1 and RCCB 9, 11 and 12 via the relay 6XA1.

ECMU 2 (and 1 when 2 fails or inoperative) manage RCCB 4, 5, 6 and 8 viathe relay 2XA2 and RCCB 10 via the relay 6XA2.

a l T r a i n i n g



24−50


49/67

L u f t h a n s a T e c h n i c a


s O n l y


Figure 23 Galley and Commercial Load Control

a l T r a i n i n g



24−50


50/67



s O n l y


SERVICE BUS CONTROL

External power A supplies AC and DC service buses.

The ECMUs sense the aircraft power supply via the status of the MAINTE-NANCE SERVICE BUS P/B position.

Once EXT A is available, ECMUs 1 and 2 will control the associated RCCBs

and will allow the service buses to be supplied.ECMU 1 monitors and controls 7XN1, 53XN and 57XN.

ECMU 2 monitors:

The RCCBs 6XN2 and 7XN2.

TR 2 supply contactor 2PU (TR supply from AC BUS 2−3)

The position of the MAINT BUS P/B.

ECMU 2 controls the RCCBs 6XN2, 7XN2, 2XX, 3XX, 4XX, 6XX, 23XX and27XX.

These relays will be energized to close when no anomaly is detected and whenthe COMMERCIAL P/B is in the AUTO position.

If the COMMERCIAL P/B is set to OFF, the COMMERCIAL OFF legend is dis-

played on the ECAM, all RCCBs open and the SERVICE BUS is no longer sup-plied. Thus, all commercial equipment and galleys are no longer supplied.

a l T r a i n i n g



24−50


51/67



s O n l y


Figure 24 Service Bus Control

a l T r a i n i n g



24−50


52/67



s O n l y


LOAD MANAGEMENT DESCRIPTION

SYSTEM MANAGEMENT

The ELMU is equipped with a pin programming which indicates the type of air-craft and the various options installed.

The ELMU manages the electrical loads of several aircraft systems and com-

ponents. This enables a normal load consumption to be restored in the electri-cal network and to avoid any overloads.

These systems and components consist of:

The Air flow management and the Ventilation, the ELMU controls the fansvia the Ventilation Controller (VC)

The passenger In Flight Entertainment System (IFES)

Water ice protection (Ice Protection Control Units (IPCU) and Potable WaterControl Units (PWCU))

Heating (Lower Deck Mobile Crew Rest (LDMCR))

Galleys

The ELMU is a GO item. In case of aircraft dispatch with a faulty ELMU, the

ELMU P/B on the 235VU must be set to OFF.When the ELMU is deselected, all managed systems are still available, and theECMUs and GCUs control the AC and DC busbar overloads.

HEAVY CONSUMER MONITORING

The Hydraulic System Monitoring Unit (HSMU) is monitored by the ELMU toinform the start of one or several pumps in the hydraulic system.

The fuel jettison system is monitored to inform the ELMU when a large numberof fuel pumps start to operate at the same time.

This monitoring enables these heavy consumers to be anticipated and manageloads with maximum efficiency.

ELECTRICAL SYSTEMSThe ELMU is connected to computers in the electrical generation system inorder to obtain the configuration of the electrical network.

These computers are the 4 GCUs, which are connected to the GAPCU, andthe Electrical Contactor Management Units (ECMU) 1 and 2.

DATA LOADING

The software on a disk governs the shedding priorities.

The Multipurpose Disk Drive Unit (MDDU) is used to upload the ELMU mana-ged load database from the disk.

This software mainly contains, for each managed load:

a priority

the power supply busbar

the limit of power consumption

The MDDU also enables the previously uploaded database to be retrieved.

The operational program of the ELMU consists of:

the operational program (electrical load management, data storing, BITE)

the characteristics of the electrical network

the characteristics of the electrical power sources (IDGs, APU GEN, GPU)

the characteristics of the heavy consumers (hydraulic system electric

pumps, jettison system)It is possible to download data stored in the ELMU, which contains data relatedto the power sources, the electrical network configuration and the managedloads.

POWER SUPPLY

The ELMU is supplied by two main DC power sources, which are:

The DC BAT BUS (301 PP), which is the ELMU normal 1 supply

The DC BUS 2 (206 PP), which is the ELMU normal 2 supply

The HOT BUS 1 (701 PP) supplies the ELMU as a backup power supply.

This supply is automatically connected for 30 seconds if its two main DC powersupplies are lost.

c a l T r a i n i n g



24−50


53/67

L u f t h a n s a T e c h n i c



Figure 25 ELMU Interface




24−50


54/67




LOAD MANAGEMENT INTERFACES

The ELMS consists of these components:

the ELMU

a disk that contains the ELMU operational program

a disk that contains the ELMU managed load database

an ELMU P/B (235VU) on the cockpit overhead panel (ELEC panel)

INTERFACE

The ELMU is connected to several computers, systems and components toknow their status.

There is an interface between the ELMU and:

the managed systems (ventilation, galleys...)

From the ELMU to the Ventilation Controller (VC), data and status controlsignals from these components:

− recirculation fans 1, 2 and 3

− galley and lavatory extraction fan

− cabin air extraction fan (if installed)

Data to inform the ELMU if the LDMCR option is installed on the aircraft.

The ELMU has also interfaces with the RCCBs, which include a circuit breakerand a current transformer in the same unit.

The ELMU measures the current intensity through the RCCBs and controlsthem for supply of the managed loads at the same time.

the heavy consumers (HSMU, fuel jettison system)

From the HSMU to the ELMU (discretes):

− signal related to starting and shutdown of the Green, Blue and Yellowhydraulic system electric pumps.

From the jettison system to the ELMU (discretes):

− signal related to starting of the jettison system.

the electrical systems

Data is exchanged between the ELMU and these components/system:

− Electrical Contactor Management Units (ECMU) 1 and 2

From the ECMUs to the ELMU, data related to the status of these con-tactors:

Generator Line Contactors (GLC) 1 thru 4

External Power Contactors (EPC) A and B

APU GLC

System Isolation Contactor (SIC)

Bus Tie Contactor (BTC) 1 thru 4.

From the ELMU to the ECMUs (discretes), ELMU FAULT data.

− Generator Control Units (GCU) 1, 2, 3 and 4

From each GCU to the ELMU (on ARINC 429 buses), data related to thestatus of these contactors:

Generator Line Contactor (GLC) 1, 2, 3 or 4

External Power Contactors (EPC) A and B

APU GLC

System Isolation Contactor (SIC)

Bus Tie Contactor (BTC) 1, 2, 3 or 4.

and data related to the current delivered by:

generator 1, 2, 3 or 4 (overload, current/phase, trip)

external power A and B (overload, connection request, current/phase)

APU (overload, ready, trip, current/phase).

Data related to the status of the contactors and to the current consumedby the APU generator and the external power A and B is acquired by theGround and Auxiliary Power Control Unit (GAPCU). The GAPCU sendsthis data simultaneously to the four GCUs that are connected to theELMU.




24−50


55/67








24−50


56/67

L u f t h a n s a T e c h n i



INTERFACE (cont‘d)

SDACs 1 & 2

From the ELMU to the SDACs (by ARINC 429 bus):

− ELMU FAULT data (for ECAM WARNING)

− ELMU class 2 failure for INOP

− messages related to the shed systems (GALLEY SHED, GALLEY PAR-TIALLY SHED, COMMERCIAL PARTIALLY SHED, COMMERCIALOFF).

From the ELMU to the SDACs (discretes), ELMU FAULT data (for ECAMWARNING)

CMCs 1 & 2

From the ELMU to the CMCs:

− ELMU FAULT data

− the LRU identification

− the BITE maintenance messages

− data for the interactive BITE functions

From CMC1 to the ELMU:− data related to the current flight number, the time, date and the aircraft

identification.

− data for the interactive BITE functions.

Cabin Intercommunication Data Systems (CIDS‘s) 1 & 2

From the ELMU to the FAP via the CIDS Directors (by ARINC 429 buses),status of the shedding for:

− cabin ventilation

− passenger entertainment system

− galleys

− water ice protection system.From the CIDS director 1 (2) to the ELMU, data related to the load status ofthe groups that include the five IPCUs and the PWCU.

the MDDU for uploading and downloading of ELMU operational programdisk and ELMU managed load database disk.

Other Interfaces

Interface with relay 8HK

− If the LDMCR is installed, the ELMU controls relay 8HK for managementof the LDMCR heating loads.

Interface with relay 402MK

The auxiliary contact of relay 402MK tells the ELMU if the passenger enter-tainment system is connected to the aircraft electrical network.

i c a l T r a i n i n g



24−50


57/67

L u f t h a n s a T e c h n




n i c a l T r a i n i n g



24−50


58/67

L u f t h a n s a T e c h n

F o r T r a i n i n g P u r p o s

e s O n l y


ELMU OPERATION

LOAD SHEDDING

The managed systems are split into groups/blocks with individual control fromthe ELMU:

Quantity per aircraft: 25

Power quantity per group per block: Up to 15 kVA

Total power on aircraft: 250 kVA.

They also classified according to priority levels:

Priority 1: At worst, small impact for cabin crew (workload, comfort) and onpassenger comfort

Priority 2: Significant impact for cabin crew and, at worst, small perceptible im-pact on passenger comfort

Priority 3: Substantial impact on passenger comfort

The equipment and components are automatically shed when required. Thisshedding is ensured by:

Either by control of their RCCB, when they have a substantial load during

operation (30A or 50 A current, 115VAC). Or by direct control on their power relay.

The overload situation may results from Engine/IDG loss, connection of toomany consumers in degraded configurations or heavy load demand.

In overload condition, the ELMU identifies the configuration of the electrical net-work (via the electrical system) in order to determine the supply of each item.The ELMU will calculate the current value of the overloaded electrical sourcefor the shedding.

From the overloaded source, the ELMU identifies the consumers that can beshed, regarding their status, their consumption and their level of priority.

The ELMU then sends shedding commands to the selected consumers in order

to restore a normal consumption on the source.Operating principle when shedding is necessary:

Identification of the overloaded power source and of the overload value

Identification of managed loads connected to the concerned Power source

Identification of the loads to be switched off (based on consump

Documents

ATA 24 ELECTRICAL POWER.pdf