AC EMERGENCY GENERATION - DESCRIPTION AND OPERATION

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1. General
The AC emergency generation enables part of the distribution network to be recovered in case of:

loss of the two main generation sources and,
unavailability of the auxiliary generation.

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2. Component Location

AC Emergency Generation - Component Location

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C ALL
1XE	CONTROL UNIT-CSM/G		125	24-24-34
2XE	GLC-EMER	106VU	125	24-24-55
8XE	CSM/G		148	24-24-51
14XE	ANN-EMER ELEC PWR/RAT/&/EMER GEN	21VU	211	24-24-00
15XE	CNTOR-AC ESS BUS SWITCHING	106VU	125	24-24-55
23XE	P/BSW-EMER ELEC PWR/EMER GEN TEST	21VU	211	24-24-00
24XE	P/BSW-EMER ELEC PWR/MAN ON	21VU	211	24-24-00
33XE	TIMER	106VU	125	24-24-00

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3. System Description

Electrical Emergency Generating System - Schematic

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4. Component Description
The emergency generation system is mainly composed of:

a Constant Speed Motor/Generator (CSM/G) including a hydraulic motor and an AC generator,
a Generator Control Unit (GCU).

A hydraulic motor drives the emergency generator.
A servo valve speed regulator controls the speed: it transforms the oil flow of the Blue hydraulic system into constant speed for the generator.
When emergency conditions are met, this Blue system is supplied by a Ram Air Turbine (RAT).

NOTE: The Blue hydraulic system is supplied by an electric pump in normal configuration.

A. Constant Speed Motor/Generator FIN: 8-XE

(1) Hydraulic motor:

Powered by the Blue hydraulic circuit (RAT in emergency configuration; electrical hydraulic pump in test),
speed regulation by servovalve,
integrated solenoid control valve.

(2) AC generator:

Three phase 115V/200V - 400 Hz (12000 rpm),
output power: 5 KVA continuously,
oil cooled.

(3) Hydraulic motor:

Energized by the Blue hydraulic circuit (by RAT in emergency configuration and by the electrical hydraulic pump during tests)
Speed control through servo-valve
Integrated solenoid control-valve.

(4) AC generator:

Three-phase 115V/200V, 400 Hz (12000 rpm)
Output power: continuous 5.4 kVA
Oil-cooled.

B. Generator Control Unit
The GCU main functions are:

to control the servo-valve excitation for speed regulation,
to regulate the generator voltage by the field current,

to protect the network and the generator by controlling the associated line contactor and generator field current.

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CONTROLS/PROTECTIONS OF GCU ! TIME DELAY ! EFFECTS

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- Over/Under Voltage (OV/UV) ! 3-5 s ! Line contactor opens, generator

- Over Frequency (OF) ! 3-5 s ! de-energization and control

- Under Frequency (UF) ! 300 ms ! valve close (FAULT warning on,

- Shorted PMG ! 3-5 s ! RAT & EMER GEN warning light).

- Fast overspeed shutdown ! 150 ms !

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5. Operation

A. Control and Indicating Circuits

(1) Emergency generator switching

Electrical Emergency Switching - Schematic

EMER & AC ESS BUS Contactors Control - Logic Diagram

The emergency generator is switched through:

contactor 2XE (emergency generator line contactor or EMER GLC), and
contactor 15XE (AC ESS BUS contactor).
timer 33XE, it avoids the closure of the contactor 15XE in case of an electric transfer and close this contactor 15XE only in emergency configuration.

The emergency generator has priority over its network and supplies the essential busbars (4XP, 8XP, 4PP, 8PP).
Supply to the line contactor (EMER GLC) only depends on the availability of the emergency generator.
Supply of section 1 of contactor 15XE depends on several conditions:

the availability of the emergency generator,
the failure of one of the 2 normal TR's (TR 1 or TR 2),
the failure of the DC ESS BUS SUPPLY and/or DC NORM BUS 1 switching contactors (4PC/1PC1).

(2) RAT extension logic and CSM/G control logic

RAT Extension Logic and CSM/G Control Logic - Schematic

(a) RAT extension logic
3 different logics control RAT extension:

the automatic electrical logic: this energizes solenoid N°.1 when there is loss of voltage at busbars 1XP and 2XP and speed V > 100 kts,
the manual electrical logic: this energizes solenoid No. 2 directly, via OVRD ELEC pushbutton switch,
the manual hydraulic logic: this energizes solenoid No. 1 directly, via OVRD HYD pushbutton switch.

(b) CSM/G control logic
3 different logics control energization of the emergency generation:

the automatic electrical logic: this is identical to that of the RAT extension,
the manual electrical logic: this is identical to that of the RAT extension,
the electrical test logic: this simulates the automatic electrical logic because it allows the emergency generator to be coupled to the Blue hydraulic system (supplied by the hydraulic electric pump) while inhibiting RAT extension.

(3) Controls and indications in the cockpit

Electrical Emergency Generation System - Control System ** ON A/C NOT FOR ALL

Electrical Emergengy Generation System - Control System ** ON A/C NOT FOR ALL

(a) The RAT and CSM/G are:

automatically controlled by AC BUS 1 and AC BUS 2 loss and V > 100 kts,
or manually by means of the EMER ELEC PWR/MAN ON guarded pushbutton switch on the EMER ELEC PWR section of the overhead panel 21VU.

When a failure of the AC BUS 1 and 2 occurs, simultaneously:

the RAT is automatically extended,
the emergency generator is automatically coupled to AC and DC ESS busbars,
the red FAULT legend comes on on RAT & EMER GEN annunciator until the emergency generator is available.

In all cases, the pilot has to press EMER ELEC PWR/MAN ON pushbutton switch in order to confirm the automatic logic. Red FAULT legend disappears if coupling is obtained.

(b) A test of the emergency generator can be initiated on the ground. The procedure is controlled by the EMER GEN TEST pushbutton switch located on the EMER ELEC PWR section of overhead panel 21VU.
When EMER GEN TEST pushbutton switch is pressed and held:

ELEC page is automatically displayed on the ECAM system (on ground only),
the emergency generator is coupled to its network,
DC ESS BUS SPLY and AC ESS BUS switching line contactors (4PC/3XC) open, isolating AC and DC essential busses,
on the ECAM system: green lines between normal busbars and essential busbar disappear.
The white EMER GEN, ESS TR and the green indications of the corresponding parameters appear, green lines between EMER GEN and AC ESS and DC ESS appear.

NOTE: The ELEC page must disappear when the EMER GEN TEST pushbutton switch is released.

(c) A test of the emergency GCU can be initiated on the ground from the CFDS.
The emergency GCU is a type 3 system:
i.e. it has neither an input bus nor an output bus, it is connected to CFDIU by 2 discrete links.
The test procedure is described in

Test Procedure for GCU EMER by MCDU

B. Electrical Emergency Configuration

NOTE: For more data, REF.31-67-24.

Electrical Emergency Configuration - Upper and Lower ECAM Display Unit

(1) Electrical emergency configuration during RAT extension (<10 sec) and after landing configuration

ELectrical Emergency Configuration During RAT Deployment and in Landing Gear Extented Configuration ** ON A/C NOT FOR ALL

This configuration is the result either of the RAT extension phase or of the CSM/G shutdown after landing in emergency configuration.
The CSM/G can be switched off by the priority valve closure due to a blue hydraulic pressure drop. Nevertheless, the CSM/G is switched off through a logic controlled by both ADIRU1 (A/C speed < 100 Knots) and LGCIU1 5GA1 (main landing gear compressed).
No power source (GEN 1, GEN 2, APU GEN, EXT PWR, EMER GEN) being available, (static inverter) busbars 4XP and 901XP are supplied by battery 1 and busbar 4PP by battery 2 via static inverter through contactor 2XB.

ESS BUSES ON BAT - Upper and Lower ECAM Display Unit

NOTE: At go around, the emergency generator can be restored to the on-line status by pressing MAN ON pushbutton switch located on the EMER ELEC PWR section of overhead panel 21VU.

(2) Electrical emergency configuration with CSM/G running

Electrical Emergency Configuration with CSM/G Running ** ON A/C NOT FOR ALL

(3) Electrical Emergency Configuration on the ground, with speed < 50 kts.

Electrical Emergency Configuration on the Ground with speed < 50kts ** ON A/C NOT FOR ALL

In this configuration, busbar 4XP is shed. Battery 1 supplies busbar 901XP via the static inverter. Battery 2 supplies busbar 4PP.

NOTE: At A/C speed approximately equal to 100 Knots, the BCL's control the closure of battery contactors 6PB1 and 6PB2. So that the supply of static inverter contactor 2XB depends on the position of battery contactors.

NOTE: A list of available functions in emergency configuration is shown in the following figures:

Available Functions in Emergency Configuration

Available Functions IN Emergency Configuration

Available Functions in Emergency Configuration

C. Electrical Smoke Configuration

Smoke Detection - Upper and Lower ECAM Display Unit

Electrical Smoke Configuration ** ON A/C NOT FOR ALL

This configuration is the same as the electrical emergency configuration.
In addition, one fuel pump per wing is directly supplied by generator 1 upstream the generator line contactor 1 (GLC1).
Description of smoke procedure:
Smoke evacuation:

OXYGEN/MASK MAN ON pushbutton switch to ON,
VENTILATION/BLOWER and EXTRACT pushbutton switches to OVRD (open fully the conditioned air inlet valve and partially the skin air outlet valve),
VENTILATION/CAB FANS pushbutton switch to OFF (stops recirculation).

If the smoke persists after 5mn:

Smoke isolation:

EMER ELEC PWR/GEN 1 LINE pushbutton switch to OFF (opens GLC1),
EMER ELEC PWR/MAN ON pushbutton switch (RAT extension),
ELEC/APU GEN pushbutton switch to OFF,
ELEC/GEN 2 pushbutton switch to OFF (2 fuel pumps supplied by Gen 1 upstream GLC1).

Before landing gear extension:

GEN 2 pushbutton switch to ON
GEN 1 LINE pushbutton switch to ON.

NOTE: If, in normal configuration, GEN 1 LINE pushbutton switch is released, the EMER GEN 1 LINE OFF message is displayed on the upper ECAM display unit.

D. Electrical Configuration in case of Failure of Both Engines
If both AC BUS 1 and AC BUS 2 buses are lost and the aircraft speed is above 100 knots, the Ram Air Turbine (RAT) extends automatically. This powers the Blue hydraulic system, which drives the CSM/G by means of a hydraulic motor. This CSM/G supplies the AC ESS BUS and the DC ESS BUS, via the essential transformer rectifier (ESS TR).
If the RAT stalls or if the aircraft is on the ground with the speed below 100 knots, there is no sufficient power to operate the CSM/G. The emergency generation network is automatically transferred to the batteries and the static inverter, and the system automatically sheds the AC SHED ESS buses and DC SHED ESS buses.
When the aircraft is on the ground:

below 100 knots, the DC BAT BUS is automatically connected to the batteries
below 50 knots, the AC ESS BUS is automatically shed, which causes the loss of all CRTs.

NOTE: During RAT extension and CSM/G coupling (about 8 seconds), the batteries power the emergency generation network.

If both AC BUS 1 and AC BUS 2 buses are lost and the aircraft speed is above 100 knots, the Ram Air Turbine (RAT) extends automatically. This powers the Blue hydraulic system, which drives the CSM/G by means of a hydraulic motor. This CSM/G supplies the AC ESS BUS and the DC ESS BUS, via the essential transformer rectifier (ESS TR).
The hydraulic power available from the RAT can supply the CSM/G down to landing.
When the aircraft is on the ground:

below 100 knots, the DC BAT BUS is automatically connected to the batteries
below 50 knots, the AC ESS BUS is automatically shed, which causes the loss of all CRTs.

NOTE: During RAT extension and CSM/G coupling (about 8 seconds), the batteries power the emergency generation network.

NOTE: If only the batteries power the emergency generation network, APU start is only available on ground (speed below 100 knots).

[Rev.10 from 2021] 2026.04.01 05:40:25 UTC