AC EXTERNAL POWER CONTROL - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The power supply control of the whole aircraft network from a ground power unit is performed from the cockpit overhead panel (Ref. AMM D/O 24-00-00-00).
This control is associated with a ground power control unit (GPCU).
The power supply control of the whole aircraft network from a ground power unit is performed from the cockpit overhead panel (Ref. AMM D/O 24-00-00-00).
This control is associated with a Ground and Auxiliary Power Control Unit (GAPCU) which permanently monitors the parameters for the quality of the electrical power supplied.
Moreover, the GAPCU permanently transmits to the Centralized Fault Display Interface Unit (CFDIU) all its fault messages, controls and monitors the APU generation.

** ON A/C NOT FOR ALL

2. Component Location

AC External Power Control (GPCU) - Component Location ** ON A/C NOT FOR ALL

AC External Power Control (GAPCU) - Component Location ** ON A/C NOT FOR ALL

AC External Power Control (GPCU) - Component Location ** ON A/C NOT FOR ALL

AC External Power Control (GAPCU) - Component Location ** ON A/C NOT FOR ALL

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
1XG	GPCU	92VU	122	24-41-34
** ON A/C NOT FOR ALL
1XG	GPCU	92VU	121	24-41-34
** ON A/C ALL
3XG	EPC	120VU	212	24-41-55
8XG	IND LT-EXT PWR/NOT IN USE	108VU	120	24-41-00
9XG	CAUT LT-EXT PWR/AVAIL	108VU	120	24-41-00
10XG	P/BSW-ELEC/EXT PWR	35VU	210	24-41-00
20XG	RCPT-EXT PWR	121AL	120	24-41-51
** ON A/C NOT FOR ALL
24XG	GAPCU	92VU	122	24-41-34

** ON A/C NOT FOR ALL

3. System Description

External Power Configuration - Block Diagram ** ON A/C NOT FOR ALL

Ground Power Control Unit (GPCU) - Schematic Diagram ** ON A/C NOT FOR ALL

Ground Power Control Unit (GAPCU) - Schematic Diagram ** ON A/C NOT FOR ALL

Ground Power Control Unit (GPCU) - Schematic Diagram ** ON A/C NOT FOR ALL

A. External Power Receptable
One external power receptable (20XG) located foward of the nose gear well enables power supply of the aircraft network up to 90 KVA.
This is perfomed by means of a single three-phase, 400 Hz, 115/200 VAC Ground Power Unit (GPU).

B. Ground Power Supply
The GPU supplies the transfer circuit through the EPC (3XG).
The effective supply of the aircraft network by means of the Bus Transfer Contactors (BTC), (Ref. AMM D/O 24-22-00-00), depends on the availability of the other generation sources and the defined priority order.

In ground configuration, these two power sources can supply all of the aircraft network:

The APU generator, to a maximum power of 115 KVA, or
The GPU, to a maximum power of 90 KVA (approximately 60KVA for the technical loads).

** ON A/C NOT FOR ALL

4. Component Description

A. Ground Power Control Unit (GPCU) Control and Protection Functions FIN: 1-XG
The GPCU has three different functions:

aircraft power supply control and network protection,
system test and self-monitoring relating to these functions
provide BITE and messages for the AC generation (GCU's and GPCU).

NOTE: The GPCU transmits command and data to and receives data from up to the GCUs.
The communication is made via RS422 serial data links.

B. Ground and Auxiliary Power Control Unit (GAPCU) Control and Protection Functions
The GAPCU controls both APU generator and external powers channels. In addition to the APU generator functions, the GAPCU has three different functions:

aircraft power supply control and network protection,
system test and self-monitoring relating to these functions
provide BITE and messages for the AC generation (GCU').

NOTE: The GAPCU transmits command and data to and receives data from up to the GCUs.
The communication is made via 1553 serial data links.

(1) Control Unit Supply
The control unit is supplied:

with 115 VAC/400 Hz, directly from the external power receptacle, by the voltage it has to analyse.
The GPCU generates 28VDC from this voltage. It is used:
for its own needs (internal plus or minus 15 V, plus or minus 5 V and + 28 V supply), to supply the aircraft power supply control and indicating circuits (EPC, EXT PWR pushbutton switch, EXT PWR NOT IN USE indicator light and EXT PWR AVAIL caution light, flight/ground network contactors),
with 28 VDC from the normal aircraft electrical network and on the ground only.

This dual supply constitutes the 28 V internal supply, peculiar to the control unit.

(2) Control Unit Supply
The control unit is supplied:

with 115 VAC/400 Hz, directly from the external power receptacle, by the voltage it has to analyse.
The GAPCU generates 28VDC from this voltage. It is used:
for its own needs (internal plus or minus 15 V, plus or minus 5 V and + 28 V supply), to supply the aircraft power supply control and indicating circuits (EPC, EXT PWR pushbutton switch, EXT PWR NOT IN USE indicator light and EXT PWR AVAIL caution light, flight/ground network contactors),
with 28 VDC from the normal aircraft electrical network and on the ground only.

This dual supply constitutes the 28 V internal supply, peculiar to the control unit.

(3) Controls
The GPCU (in association with the EXT PWR pushbutton switch) controls the connection/disconnection of the external power to/from the aircraft electrical system.
The necessary controls are achieved by means of relays.

The Pin Monitoring Relay (PMR)
This relay when energized, connects a holding supply to the GPU line contactor. It is energized when the DC input voltage (Pin E and F) is within acceptable limits (less than 42 VDC).
The External Power Available Relay (PR)
The PR when excited enables the connection of the ground power unit to the aircraft network provided none of the following protections is actived:
. over/undervoltage,
. over/underfrequency,
. incorrect phase order,
. GPCU internal fault.

Any fault detection:

prevents the ground power unit from being connected to the aircraft network,
or causes it to trip if already in line.

NOTE: When a fault is detected, the PR is no longer excited and/or inhibits illumination of the ON legend of the EXT PWR pushbutton switch.

NOTE: The PR also controls the illumination of the AVAIL legend of the EXT PWR pushbutton switch in the cockpit and the EXT PWR AVAIL caution light in the external power receptacle housing.

(4) Controls
The GAPCU (in association with the EXT PWR pushbutton switch) controls the connection/disconnection of the external power to/from the aircraft electrical system.
The necessary controls are achieved by means of relays.

The Interloch Monitoring Relay (IMR)
This relay when energized, connects a holding supply to the GPU line contactor. It is energized when the following conditions exist:
- external power Pin E voltage is higher than 12.6 Volts
- external power protection latch is erroneous
- interlock fault is erroneous:
. the interlock voltage fault is detected when AC voltage is measured higher than 60VAC or DC voltage is measured higher than 45VDC.
The External Power Ready Relay (PRR)
The PRR when excited enables the connection of the ground power unit to the aircraft network provided none of the following protections is actived:
. over/undervoltage,
. over/underfrequency,
. incorrect phase order,
. GAPCU internal fault.

Any fault detection:

prevents the ground power unit from being connected to the aircraft network,
or causes it to trip if already in line.

NOTE: When a fault is detected, the PRR is no longer excited and/or inhibits illumination of the ON legend of the EXT PWR pushbutton switch.

NOTE: The PRR also controls the illumination of the AVAIL legend of the EXT PWR pushbutton switch in the cockpit and the EXT PWR AVAIL caution light in the external power receptacle housing.

(5) Protections

Over/underfrequency (OF, UF)
The control unit permanently monitors the frequency of phase A voltage of the external power receptacle.
The over/underfrequencies protection are triggered when the frequency becomes higher/lower than a certain threshold.
Over/undervoltage (OV, UV)
The control unit permanently monitors the voltage of the three phases of the external power receptacle.
The undervoltage protection is triggered when the voltage of the lower phase becomes lower than a certain threshold.
Incorrect phase order (IPS)
This detection is performed from voltage information of phases A and B of the external power receptacle.
After excitation of the ground power unit generator, the control unit analyzes the phase order of the voltage supply. When the voltage is incorrect, the GPCU prevents the closure of the PR relay (protection of the three phase consumers).

NOTE: This protection is effective in case of:
cross connection between any two phases,
and also if a phase and the neutral are crossed.
A table listing these functions is shown below:

GPCU PROTECTIONS

------------------------------------------------------------------------------I

I FUNCTION ISENSING I THRESHOLD ITIME DELAY ITRIPSI REMARKS I INHIBITION I

------------------------------------------------------------------------------I

IEP Overvol-IHighest I 124-132 I Inverse IEPC, I I I

Itage (OV) Iphase EPI Volts I IGSR'sI I I

I Ivoltage I I I I I I

I-----------I--------I-----------I-----------I-----I-------------I------------I

IEP Under- IIndivi- I 100 plus I 3 - 5 s IEPC IThis functionI I

Ivoltage Idual I or minus I IGSR'sIcovers open I I

I(UV) Iphase I 4 V I I Iphase. I I

I Iunder- I I I I I I

I Ivoltage I I I I I I

I-----------I--------I-----------I-----------I-----I-------------I------------I

IEP Overfre-IEP fre- I 433 plus I 3 - 5 s IEPC I I I

Iquency (OF)Iquency I or minus I IGSR'sI I I

I I I 3 Hz I I I I I

I-----------I--------I-----------I-----------I-----I-------------I------------I

IEP Under- IEP fre- I 363 plus I 3 - 5 s IEPC I I I

Ifrequency Iquency I or minus I IGSR'sI I I

I(UF) I I 3 Hz I I I I I

I-----------I--------I-----------I-----------I-----I-------------I------------I

IEP Phase I2 phasesI A-B-C-N I None IEPC IPrevents EPC I I

ISequence I Iphase I IGSR'sIclosure if I I

I(PS) I Isequence I I Iphase sequen-I I

I I I I I Ice is not ABCI I

I I I I I Ior if neutralI I

I I I I I Iand phase I I

I I I I I Ilead are I I

I I I I I Icrossed. I I

-------------------------------------------------------------------------------

(6) Protections

Over/underfrequency (OF, UF)
The control unit permanently monitors the frequency of phase A voltage of the external power receptacle.
The over/underfrequencies protection are triggered when the frequency becomes higher/lower than a certain threshold.
Over/undervoltage (OV, UV)
The control unit permanently monitors the voltage of the three phases of the external power receptacle.
The undervoltage protection is triggered when the voltage of the lower phase becomes lower than a certain threshold.
Incorrect phase order (IPS)
This detection is performed from voltage information of phases A and B of the external power receptacle.
After excitation of the ground power unit generator, the control unit analyzes the phase order of the voltage supply. When the voltage is incorrect, the GAPCU prevents the closure of the PRR relay (protection of the three phase consumers).

NOTE: This protection is effective in case of:
cross connection between any two phases,
and also if a phase and the neutral are crossed.
A table listing these functions is shown below:

GAPCU PROTECTIONS

-------------------------------------------------------------------------------

! External Power ! SENSING ! THRESHOLD ! TIME DELAY ! TRIPS!

! FUNCTION ! ! ! ! !

!--------------------!-----------------!---------------!---------------!------I

!Overvoltage (0V) !Highest EP phase !130 +/- 1.5V !Inverse Curve !IMR, !

! ! ! !(max) !EPRR !

!--------------------!-----------------!---------------!---------------!------!

!Undervoltage (UV1) !Lowest EP phase !101.5 +/- 1.5V !4.5 seconds !IMR !

! ! !4V Hysteresis !(max) !EPRR !

!--------------------!-----------------!---------------!---------------!------!

!Overfrequency (OF1) !EP !435 +/- 1Hz !4.0 seconds !IMR, !

! ! !4 Hz Hysteresis!(max) !EPPR !

!--------------------!-----------------!---------------!---------------!------!

!Underfrequency (UF1)IEP !361 +/- 1Hz !4.0 seconds !IMR, !

! I !4 Hz Hysteresis!(max) !EPRR !

! (UF2)I !323 +/- 1Hz !160 milli- ! !

! ! !4 Hz Hysteresis!seconds (max) ! !

!--------------------I-----------------!---------------!---------------!------!

!External Power IEP interlock pins!60 +/- 6VAC !Such that No !IMR, !

!Interlock IE and F !45 +/- 5VDC !Damage is !EPRR !

! I ! !incurred in the! !

! ! ! !GAPCU ! !

-------------------------------------------------------------------------------

(7) BITE Functions

(a) System self monitoring and function
The same test philosophy applies for the GCU and as well as for the GPCU (Ref. 24-22-00).

(b) Interface with CFDIU
The GPCU permanently sends to the CFDIU all Fault messages detected in flight or on ground by the GPCU and GCU's.
All the information transmitted from the GPCU to the CFDIU is in "Clear English Message" form.
There are two transmission modes:

the normal mode
the menu mode.

(8) BITE Functions

(a) System self monitoring and function
The same test philosophy applies for the GCU and as well as for the GAPCU (Ref. 24-22-00).

** ON A/C NOT FOR ALL

5. Operation/Control and Indicating

A. Control and Indicating Circuits - Controls and Indicating in the Cockpit

External Power Contactor (EPC) Supply - Schematic Diagram ** ON A/C NOT FOR ALL

As soon as the ground power unit is connected and selected on, the GPCU analyzes the voltage delivered at the external power receptacle.
If the analyzed parameters are correct:

the GPCU controls the illumination of the green AVAIL legend of EXT PWR pushbutton switch located on the overhead ELEC panel 35VU.
This pushbutton switch controls the energization of the transfer network by means of the external power contactor (EPC).
EPC supply is shown in this figure,
when the AVAIL legend of this pushbutton switch is illuminated, the EPC remains open.

NOTE: Nevertheless, the ground power unit can supply ground/flight networks in ground service configuration (Ref. AMM D/O 24-42-00-00).

when the pushbutton switch is pressed and released, the EPC closes and supplies the transfer circuit.
Blue ON legend comes on to indicate the closure of EPC (AVAIL legend goes off).

External Power Contactor (EPC) Supply - Schematic Diagram ** ON A/C NOT FOR ALL

As soon as the ground power unit is connected and selected on, the GAPCU analyzes the voltage delivered at the external power receptacle.
If the analyzed parameters are correct:

the GAPCU controls the illumination of the green AVAIL legend of EXT PWR pushbutton switch located on the overhead ELEC panel 35VU.
This pushbutton switch controls the energization of the transfer network by means of the external power contactor (EPC).
EPC supply is shown in this figure,
when the AVAIL legend of this pushbutton switch is illuminated, the EPC remains open.

NOTE: Nevertheless, the ground power unit can supply ground/flight networks in ground service configuration (Ref. AMM D/O 24-42-00-00).

when the pushbutton switch is pressed and released, the EPC closes and supplies the transfer circuit.
Blue ON legend comes on to indicate the closure of EPC (AVAIL legend goes off).

The effective supply of the aircraft network by means of the BTCs depends on the availability of the onboard main generation sources.
In the case of APU generator already supplying the transfer circuit, the supply command by means of the external power receptacle causes the opening of the APU generator line contactor.
For reference only, each channel is supplied according to the following priority order:

its generator,
the ground power unit,
the APU generator,
the second generator.

NOTE: The EXT PWR pushbutton switch is springloaded. At each impulse on the EXT PWR pushbutton switch, the EGIU controls the change of position of the external power auxiliary relay, (Ref. AMM D/O 24-22-00-00).

its generator,
the ground power unit,
the APU generator,
the second generator.

NOTE: The EXT PWR pushbutton switch is springloaded. At each impulse on the EXT PWR pushbutton switch, the GAPCU controls the change of position of the external power auxiliary relay, (Ref. AMM D/O 24-22-00-00).

B. Control and Indicating Circuits - Indicating in the External Power Receptacle Housing
Two lights located in the external power receptacle housing enable easier utilization or removal of the ground power unit by the ground personnel:

Amber EXT PWR/AVAIL caution light controlled by the GPCU, comes on to indicate that the ground power unit is operating and the voltage correct.
White EXT/PWR NOT IN USE indicator light comes on to indicate that the ground power unit does not supply the aircraft and can be disconnected.

NOTE: A lamp test of these two lights can be performed by means of the LIGHT TEST pushbutton switch located in the external power receptacle housing.

C. Communications

Communication - Block Diagram ** ON A/C NOT FOR ALL

A general schematic is shown in this figure and describes all the communications between the different systems. They are of 2 types:

communications toward the SDAC,
BITE communications.

(1) SDAC communications

(a) Table of Main Digital Signals Sent out by the Equipment to SDAC1(2)

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 1 070 01!GEN1 FREQ ! 512 ! HZ ! ! 09 ! ! ! ! GCU1 !

! 2 070 10!GEN2 FREQ ! 512 ! HZ ! ! 09 ! ! ! ! GCU2 !

! 071 01! APU GEN ! 512 ! HZ ! ! 09 ! ! ! !GCU-APU!

! ! FREQ ! ! ! ! ! ! ! ! !

! 071 10! EXT PWR ! 512 ! HZ ! ! 09 ! ! ! ! GPCU !

! ! FREQ ! ! ! ! ! ! ! ! !

! 1 072 01! GEN1 ! 256 ! V ! ! 08 ! ! ! ! GCU1 !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 2 072 10! GEN2 ! 256 ! V ! ! 08 ! ! ! ! GCU2 !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 075 01! APU GEN ! 256 ! V ! ! 08 ! ! ! !GCU-APU!

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 075 10! EXT PWR ! 256 ! V ! ! 08 ! ! ! ! GPCU !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 1 077 01! GEN1 LOAD! 256 !PCT ! ! 08 ! ! ! ! GCU1 !

! 2 077 10! GEN2 LOAD! 256 !PCT ! ! 08 ! ! ! ! GCU2 !

! 100 00! APU GEN ! 256 !PCT ! ! 08 ! ! ! !GCU-APU!

! ! LOAD ! ! ! ! ! ! ! ! !

! 1 105 01!IDG1 INLET! 256 !deg.! ! 08 ! ! ! ! GCU1 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 2 105 10!IDG2 INLET! 256 !deg.! ! 08 ! ! ! ! GCU2 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 1 106 01!IDG1OUTLET! 256 !deg.! ! 08 ! ! ! ! GCU1 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 2 106 10!IDG2OUTLET! 256 !deg.! ! 08 ! ! ! ! GCU2 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 071 11! EMER GEN ! 512 ! HZ ! ! 09 ! ! ! ! 27WV !

! ! FREQ ! ! ! ! ! ! ! ! !

! 075 11! EMER GEN ! 256 ! V ! ! 08 ! ! ! ! 27WV !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

(b) Table of Main Discrete Signals Received by the SDAC1(2)

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 002 00!AC/ESS TRU! ! ! ! 15 ! ! ! ! 15XE !

! ! CNTOR ON ! ! ! ! ! ! ! ! !

! 002 00!AC/ESS TRU! ! ! ! 15 ! ! ! ! 15XE !

! ! CNTOR OFF! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 16 ! ! ! ! 3XH !

! ! SHED BUS ! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 16 ! ! ! ! 3XH !

! ! SHED BUS ! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 00!AC ESS BUS! ! ! ! 18 ! ! ! ! 3XH !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 00!AC ESS BUS! ! ! ! 18 ! ! ! ! 3XH !

! ! ON ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 20 ! ! ! ! 11XC !

! ! FEED P/B ! ! ! ! ! ! ! ! !

! ! ALTN ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 20 ! ! ! ! 11XC !

! ! FEED P/B ! ! ! ! ! ! ! ! !

! ! NOT ALTN ! ! ! ! ! ! ! ! !

! 002 00! BUS TIE ! ! ! ! 21 ! ! ! ! 10XU !

! ! P/B OFF ! ! ! ! ! ! ! ! !

! 002 00! BUS TIE ! ! ! ! 21 ! ! ! ! 10XU !

! ! P/B ON ! ! ! ! ! ! ! ! !

! 002 01!GEN1 LINE ! ! ! ! 14 ! ! ! ! 9XU1 !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 01!GEN1 LINE ! ! ! ! 14 ! ! ! ! 9XU1 !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 01! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU1 !

! !CNTOR1 ON ! ! ! ! ! ! ! ! !

! 002 01! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU1 !

! !CNTOR1 OFF! ! ! ! ! ! ! ! !

! 002 01!AC1/AC ESS! ! ! ! 16 ! ! ! ! 13XC !

! ! CNTOR ON ! ! ! ! ! ! ! ! !

! 002 01!AC1/AC ESS! ! ! ! 16 ! ! ! ! 13XC !

! ! CNTOR OFF! ! ! ! ! ! ! ! !

! 002 10!GEN2 LINE ! ! ! ! 14 ! ! ! ! 9XU2 !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 10!GEN2 LINE ! ! ! ! 14 ! ! ! ! 9XU2 !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 10! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU2 !

! !CNTOR2 ON ! ! ! ! ! ! ! ! !

! 002 10! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU2 !

! !CNTOR2 OFF! ! ! ! ! ! ! ! !

! 002 10!AC2/AC ESS! ! ! ! 16 ! ! ! ! 14XC !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 10!AC2/AC ESS! ! ! ! 16 ! ! ! ! 14XC !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 11! APU GEN ! ! ! ! 14 ! ! ! ! 3XS !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 11! APU GEN ! ! ! ! 14 ! ! ! ! 3XS !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! EXT PWR ! ! ! ! 15 ! ! ! ! 3XG !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 11! EXT PWR ! ! ! ! 15 ! ! ! ! 3XG !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! GALLEY ! ! ! ! 17 ! ! ! ! 2XA !

! ! SHED P/B ! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! GALLEY ! ! ! ! 17 ! ! ! ! 2XA !

! ! SHED P/B ! ! ! ! ! ! ! ! !

! ! NOT OFF ! ! ! ! ! ! ! ! !

! 002 11!EMERGENCY ! ! ! ! 22 ! ! ! ! 23XE !

! !GEN TEST ! ! ! ! ! ! ! ! !

! 002 11! NO ! ! ! ! 22 ! ! ! ! 23XE !

! !EMERGENCY ! ! ! ! ! ! ! ! !

! !GEN TEST ! ! ! ! ! ! ! ! !

! 004 11! MAIN ! ! ! ! 27 ! ! ! ! 6XA !

! ! GALLEY ! ! ! ! ! ! ! ! !

! ! SHED ! ! ! ! ! ! ! ! !

! 004 11! NO MAIN ! ! ! ! 27 ! ! ! ! 6XA !

! ! GALLEY ! ! ! ! ! ! ! ! !

! ! SHED ! ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

(2) SDAC communications

(a) Table of Main Digital Signals Sent out by the Equipment to SDAC1(2)

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 1 070 01!GEN1 FREQ ! 512 ! HZ ! ! 09 ! ! ! ! GCU1 !

! 2 070 10!GEN2 FREQ ! 512 ! HZ ! ! 09 ! ! ! ! GCU2 !

! 071 01! APU GEN ! 512 ! HZ ! ! 09 ! ! ! ! GAPCU !

! ! FREQ ! ! ! ! ! ! ! ! !

! 071 10! EXT PWR ! 512 ! HZ ! ! 09 ! ! ! ! GAPCU !

! ! FREQ ! ! ! ! ! ! ! ! !

! 1 072 01! GEN1 ! 256 ! V ! ! 08 ! ! ! ! GCU1 !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 2 072 10! GEN2 ! 256 ! V ! ! 08 ! ! ! ! GCU2 !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 075 01! APU GEN ! 256 ! V ! ! 08 ! ! ! ! GAPCU !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 075 10! EXT PWR ! 256 ! V ! ! 08 ! ! ! ! GAPCU !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

! 1 077 01! GEN1 LOAD! 256 !PCT ! ! 08 ! ! ! ! GCU1 !

! 2 077 10! GEN2 LOAD! 256 !PCT ! ! 08 ! ! ! ! GCU2 !

! 100 00! APU GEN ! 256 !PCT ! ! 08 ! ! ! ! GAPCU !

! ! LOAD ! ! ! ! ! ! ! ! !

! 1 105 01!IDG1 INLET! 256 !deg.! ! 08 ! ! ! ! GCU1 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 2 105 10!IDG2 INLET! 256 !deg.! ! 08 ! ! ! ! GCU2 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 1 106 01!IDG1OUTLET! 256 !deg.! ! 08 ! ! ! ! GCU1 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 2 106 10!IDG2OUTLET! 256 !deg.! ! 08 ! ! ! ! GCU2 !

! ! TEMP ! ! C ! ! ! ! ! ! !

! 071 11! EMER GEN ! 512 ! HZ ! ! 09 ! ! ! ! 27WV !

! ! FREQ ! ! ! ! ! ! ! ! !

! 075 11! EMER GEN ! 256 ! V ! ! 08 ! ! ! ! 27WV !

! ! VOLTAGE ! ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

(b) Table of Main Discrete Signals Received by the SDAC1(2)

-------------------------------------------------------------------------------

| PARAMETER LIST PARAMETER CHARACTERISTICS (NUMERIC) |

-------------------------------------------------------------------------------

-------------------------------------------------------------------------------

! 002 00!AC/ESS TRU! ! ! ! 15 ! ! ! ! 15XE !

! ! CNTOR ON ! ! ! ! ! ! ! ! !

! 002 00!AC/ESS TRU! ! ! ! 15 ! ! ! ! 15XE !

! ! CNTOR OFF! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 16 ! ! ! ! 3XH !

! ! SHED BUS ! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 16 ! ! ! ! 3XH !

! ! SHED BUS ! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 00!AC ESS BUS! ! ! ! 18 ! ! ! ! 3XH !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 00!AC ESS BUS! ! ! ! 18 ! ! ! ! 3XH !

! ! ON ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 20 ! ! ! ! 11XC !

! ! FEED P/B ! ! ! ! ! ! ! ! !

! ! ALTN ! ! ! ! ! ! ! ! !

! 002 00! AC ESS ! ! ! ! 20 ! ! ! ! 11XC !

! ! FEED P/B ! ! ! ! ! ! ! ! !

! ! NOT ALTN ! ! ! ! ! ! ! ! !

! 002 00! BUS TIE ! ! ! ! 21 ! ! ! ! 10XU !

! ! P/B OFF ! ! ! ! ! ! ! ! !

! 002 00! BUS TIE ! ! ! ! 21 ! ! ! ! 10XU !

! ! P/B ON ! ! ! ! ! ! ! ! !

! 002 01!GEN1 LINE ! ! ! ! 14 ! ! ! ! 9XU1 !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 01!GEN1 LINE ! ! ! ! 14 ! ! ! ! 9XU1 !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 01! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU1 !

! !CNTOR1 ON ! ! ! ! ! ! ! ! !

! 002 01! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU1 !

! !CNTOR1 OFF! ! ! ! ! ! ! ! !

! 002 01!AC1/AC ESS! ! ! ! 16 ! ! ! ! 13XC !

! ! CNTOR ON ! ! ! ! ! ! ! ! !

! 002 01!AC1/AC ESS! ! ! ! 16 ! ! ! ! 13XC !

! ! CNTOR OFF! ! ! ! ! ! ! ! !

! 002 10!GEN2 LINE ! ! ! ! 14 ! ! ! ! 9XU2 !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 10!GEN2 LINE ! ! ! ! 14 ! ! ! ! 9XU2 !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 10! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU2 !

! !CNTOR2 ON ! ! ! ! ! ! ! ! !

! 002 10! TRANSFER ! ! ! ! 15 ! ! ! ! 11XU2 !

! !CNTOR2 OFF! ! ! ! ! ! ! ! !

! 002 10!AC2/AC ESS! ! ! ! 16 ! ! ! ! 14XC !

! !CNTOR ON ! ! ! ! ! ! ! ! !

! 002 10!AC2/AC ESS! ! ! ! 16 ! ! ! ! 14XC !

! !CNTOR OFF ! ! ! ! ! ! ! ! !

! 002 11! APU GEN ! ! ! ! 14 ! ! ! ! 3XS !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 11! APU GEN ! ! ! ! 14 ! ! ! ! 3XS !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! EXT PWR ! ! ! ! 15 ! ! ! ! 3XG !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! ON ! ! ! ! ! ! ! ! !

! 002 11! EXT PWR ! ! ! ! 15 ! ! ! ! 3XG !

! !LINE CNTOR! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! GALLEY ! ! ! ! 17 ! ! ! ! 2XA !

! ! SHED P/B ! ! ! ! ! ! ! ! !

! ! OFF ! ! ! ! ! ! ! ! !

! 002 11! GALLEY ! ! ! ! 17 ! ! ! ! 2XA !

! ! SHED P/B ! ! ! ! ! ! ! ! !

! ! NOT OFF ! ! ! ! ! ! ! ! !

! 002 11!EMERGENCY ! ! ! ! 22 ! ! ! ! 23XE !

! !GEN TEST ! ! ! ! ! ! ! ! !

! 002 11! NO ! ! ! ! 22 ! ! ! ! 23XE !

! !EMERGENCY ! ! ! ! ! ! ! ! !

! !GEN TEST ! ! ! ! ! ! ! ! !

! 004 11! MAIN ! ! ! ! 27 ! ! ! ! 6XA !

! ! GALLEY ! ! ! ! ! ! ! ! !

! ! SHED ! ! ! ! ! ! ! ! !

! 004 11! NO MAIN ! ! ! ! 27 ! ! ! ! 6XA !

! ! GALLEY ! ! ! ! ! ! ! ! !

! ! SHED ! ! ! ! ! ! ! ! !

-------------------------------------------------------------------------------

(3) BITE communications

(a) Fault detection at system level
As an assistance for maintenance tasks, the control units (GCU-1, GCU-2, GCU-APU) have to:

collect and analyse the failures, and store the corresponding fault code (hexadecimal) in their own Non Volatile Memory (NVM)
run out requested test (ex maintenance test). Each system is fitted with a RS 422 Serial link interface in order:
. to transmit the contents of current flight from the NVM and receive test requests and give the results.

(b) GPCU
The GPCU transmits the fault messages in clear English to the CFDIU (the CFDIU is connected to the GPCU by a discrete input and an ARINC 429 output bus).
It is also the interface between the CFDIU and the various control units (GCU1, GCU2, APU GCU).
The control units are connected to the GPCU by RS422 serial data links.

1 Operation in normal mode
The GPCU receives the fault information recorded by the GCU's, compiles them with its own failures and transmits for the whole system a list of the failures in clear language and starting from the most recent. When a failure is identified, the information is permanently transmitted with the ATA reference of the LRU or of the faulty circuit up to the beginning of the next flight.
The CFDIU records all the failures - Class I or II and internal to the system - transmitted by the GPCU in flight to inscribe them in the aircraft LAST LEG REPORT. The most recent failure is the first to be displayed on the MCDU.

2 Operation in menu mode
In menu mode, 3 selections are possible: LAST LEG REPORT, TEST and CLASS 3 FAULTS.

a LAST LEG REPORT
When pressing the corresponding key (in the SYSTEM REPORT/TEST page)

Reading of Class 3 Faults on MCDU ** ON A/C NOT FOR ALL

All the class I and II flight and ground failures of the current flight are displayed. The MCDU display order is as follows:

the flight messages (the most recent flight failure first),
then GND and the ground messages (the most recent ground failure first).
At GPCU power up on the ground, the contents of the various NVM's (GCU's and GPCU) for the current flight is recovered in the order GPCU, GCU1, GCU2 and APU GCU. All the messages (flight and ground) become then ground messages.

b TEST
When pressing the corresponding key

Reading of Class 3 Faults on MCDU ** ON A/C NOT FOR ALL

a test is generated and taken into account by the GPCU. The test request is transmitted by the discrete input signal from the CFDIU.
Test logic:

ground signal for 500 ms + or - 10 percent = request for test,
open circuit = no test.

NOTE: The test mode is only available on the ground.
The GPCU transmits the request for test to the GCU's and the test results of all the control units (GCU1, GCU2, APU GCU and GPCU) to the CFDIU. When the test takes more than 3 seconds the system transmits the TEST WAIT message to inform the users that his request is being processed. The TEST WAIT message remains until the test result is available. The test result is transmitted three times and then the GPCU returns automatically in normal mode.

NOTE: The results remain displayed on the MCDU display unit until the key adjacent to the RETURN line is pressed.
The test cannot be initiated in the phases 2 to 8 (see ATA Ref. 31-32-00).
In the phase 9, if the test is initiated when one engine or the APU is running, one of the following messages is displayed at the end of the test of the channel concerned:

--------------------------------------------------------

GENERATOR CHANNEL MESSAGE

RUNNING

---------------------------------------------------------

IDG 1 MAIN 1 GCU1 TEST NOT RUN

IDG 2 MAIN 2 GCU2 TEST NOT RUN

APU APU GCU APU TEST NOT RUN

c Class 3 faults
When pressing the corresponding key

Reading of Class 3 Faults on MCDU ** ON A/C NOT FOR ALL

the class III faults occured during the current flight are displayed (see TSM manual).

(4) BITE communications
The GAPCU transmits command and data to and receives data from up to the two GCUs (GCU 1, 2).
The communication is made via MIL-STD-1553-B link.
The GAPCU is able to read fault data from its own BITE and from the NVMs in each GCU on the ground or in flight.
The GAPCU is able to initiate its own and each GCUs maintenance BITE when requested by the Centralized Fault Display System (CFDS).
If the GAPCU has lost the communication with a GCU, it generates a message to the CFDS indicating the failed GCU communication.

(a) GAPCU
The GAPCU transmits the fault messages in clear English to the CFDIU (the CFDIU is connected to the GAPCU by a discrete input and an ARINC 429 output bus).
It is also the interface between the CFDIU and the various control units (GCU1, GCU2).
The control units are connected to the GAPCU by 1553 serial data links.

1 Operation in normal mode
The GAPCU receives the fault information recorded by the GCU's, compiles them with its own failures and transmits for the whole system a list of the failures in clear language and starting from the most recent. When a failure is identified, the information is permanently transmitted with the ATA reference of the LRU or of the faulty circuit up to the beginning of the next flight.
The CFDIU records all the failures - Class I or II and internal to the system - transmitted by the GAPCU in flight to inscribe them in the aircraft LAST LEG REPORT. The most recent failure is the first to be displayed on the MCDU.

2 Operation in menu mode
See Para 6. (BITE test)

D. Automatic Periodic Test
As soon as the GPCU is supplied (Aircraft on ground and engines shut down) it will automatically perform the test (GPCU and GCUs) and will store the failure (if any) in the corresponding NVM for transmission through the GPCU to the CFDIU.
Moreover, the GPCU will activate the BITE Message discrete. This information is provided to the SDACs via the EGIU1 to be written on the ECAM status page.
As soon as the GAPCU is supplied (Aircraft on ground and engines shut down) it will automatically perform the test (GAPCU and GCUs) and will store the failure (if any).
Moreover, the GAPCU will activate the BITE Message discrete. This information is provided to the SDACs to be written on the ECAM status page.

** ON A/C NOT FOR ALL

6. BITE Test

A. Description

The GAPCU is a type 1 system.
The GAPCU performs the following functions:

communication with the CFDS,
communication with up to the four generator control units,
detection of any failure affecting the external power channel and/or the APU Ancillary generator,
identification of the Line Replaceable Unit (LRU) responsible for the external power channel failure,
memorization of the information pertaining to the failure in a Non Volatile Memory (NVM).

B. Results of power-up Test

(1) Communication with the CFDIU

BITE Communication - Block Diagram ** ON A/C NOT FOR ALL

The GAPCU is connected to the CFDIU via separate ARINC 429 links.
The GAPCU transmits data to and receives data from the CFDIU
The GAPCU communicates with the CFDIU in either of the two modes: normal or interactive mode.

(a) Normal mode

The normal mode starts after the GAPCU has completed all its power up and initialization routines. This normal mode runs continuously, unless one of the following conditions occurs:

initiation of interactive mode,
GAPCU failure (BITE bypass),
loss of GAPCU power.

During the normal mode operation, the GAPCU provides the following communications with the CFDIU

reception of BITE commands and parametric data,
transmission of the equipment identification data,
transmission of system fault data.

For each fault, the GAPCU transmits a message in English language to the CFDS. The message is encoded in ISO5 alphabet.
The dialogue principle is the same as for all the other type 1 systems in communication with the CFDIU.
Refer to chapter 31-32-00 for more detailed data.

(b) Interactive mode

The GAPCU stops normal mode transmission and enters the interactive mode when it receives the order from the CFDIU. The GAPCU transmits the EPGS (External Power Generation System) main menu.

The EPGS main menu comprises eight functions which are:

EPGS main menu on MCDU ** ON A/C NOT FOR ALL

LAST LEG REPORT,
PREVIOUS LEGS REPORT,
LRU IDENTIFICATION,
GROUND REPORT,
TROUBLE SHOOTING DATA,
CLASS 3 FAULTS REPORT,
TEST,
SPECIFIC DATA.

The content of each function is described in Para. B. (Description of the Interactive Mode Function)
For more information: Ref. 31-32-00 (CFDIU).

(2) Communication with (up to) the two GCUs

BITE Communication - Block Diagram ** ON A/C NOT FOR ALL

The GAPCU transmits command and data to and receives data from up to the two GCUs (GCU 1, 2).
The communication is made via MIL-STD-1553-B link.

The GAPCU is able to read fault data from its own BITE and from the NVMs in each GCU on the ground or in flight.
The GAPCU is able to initiate its own and each GCUs maintenance BITE when requested by the CFDS.
If the GAPCU has lost the communication with a GCU, it generates a message to the CFDS indicating the failed GCU communication.

(3) Detection of any failure affecting the external power channel.

Ref. Para. C.(BITE/TEST Function).

(4) Identification of the LRU responsible for the failure.

Ref. Para. C. (BITE/TEST Function).

(5) Memorization of the information pertaining to the failure in the Non Volatile Memory (NVM)

The GAPCU contains a NVM. The NVM is implemented on the EEPROM. Any fault identified by the GAPCU BITE is recorded in the GAPCU NVM.
The GAPCU NVM is structured like the other type 1 computers (Ref. 31-32-00)-(CFDIU).

C. Description of the Interactive Mode Function

EPGS - Maintenance Operation : LAST LEG REPORT ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : PREVIOUS LEGS REPORT ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : LRU IDENTIFICATION ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : GROUND REPORT ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : TROUBLE SHOOTING DATA ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : CLASS 3 FAULTS ** ON A/C NOT FOR ALL

EPGS - Maintenance Operation : TEST ** ON A/C NOT FOR ALL

D. BITE Test Function

The GAPCU has an initialization test capability and three different types of BITE:

signature/monitor,
isolation,
maintenance.

Isolation BITE has the highest priority followed by maintenance BITE and then signature BITE.

(1) TEST initialization

Test initialization is made at power up, when the ELEC/EXT pushbutton switch is cycled and the watchdog has timed-out or after a maintenance BITE request.

(2) Signature/monitor BITE

Monitoring is performed as long as the GAPCU is powered except when the BITE is bypassed or if the maintenance BITE or isolation BITE has precedence.
The monitor BITE does not change the contents of any RAM used by the control and protection software. It does not change the state of any of the outputs nor stimulate any sense circuitry.
Once a given fault has been determined an indication of the fault is written in the NVM.
If the same fault is detected again during the current flight, the number of occurrences of that fault is also indicated, up to a maximum of four times.

(3) Fault isolation BITE

In the event of a protective trip, the fault isolation software determines whether the trip is due to external fault trip condition or due to faulty sense circuitry within the controller.

The fault isolation software stimulates the sense circuitry associated with the trip which has occurred where appropriate. If the sense circuitry responds to the stimulus as expected then the fault is judged to be external to the controller.

The fault isolation BITE primary function is to identify the failed LRU after a protective trip has occurred. The protective trips are classified as any fault detected by the controller that will result in a Power Ready Relay (PRR) trip. After a failure has been detected and indicated by the protective latch as being true, the corresponding isolation routine will be executed.
Note that after a protective trip has been isolated (isolation routine is completed and the fault determined) no further isolation is executed until the protection latch has been cleared (i.e. the External Power Switch (EPS) is cycled or a cold start is executed).

(4) Maintenance BITE

The maintenance BITE is initiated upon request from the CFDIU.

(a) Stage 1 - Starting maintenance BITE

All the following conditions must be present for a GAPCU maintenance BITE procedure to begin:

a test (maintenance BITE request) signal has been received from the CFDIU (via the ARINC 429 receiver),
a flight phase 1 or 10 signal is being received from the CFDIU,
a null failure monitoring and storage command is being received from the CFDIU,
"The aircraft is on the ground" discrete input is present,
Isolation BITE is not in progress.

If all the conditions are met, the message TEST IN PROGRESS is generated to the CFDIU and the maintenance BITE procedure continues with stage 2.

NOTE: The GAPCU returns to the normal mode:
- if any of the conditions is not met or,
- if the GAPCU receives a log off command from the CFDIU or,
- a return command is pushed at menu level of the CFDIU or,
- for any protocol problem with the CFDIU.

(b) Stage 2 - GAPCU control of GCU maintenance BITE

The GAPCU initiates a maintenance BITE sequence in each of the GCUs by sending a maintenance BITE request signal to each GCU via its MIL-STD-1553-B communication link.
Once initiated, each GCU is in control of its own maintenance BITE sequence (on ground and engine not running). At the end of the maintenance BITE sequence (if done), each GCU leaves the maintenance BITE and stores the messages or fault codes for interrogation by the GAPCU.

(c) Stage 3 - GAPCU maintenance BITE sequence

The maintenance BITE sequence terminates by the completion of all the procedures. All fault codes generated during the GAPCU maintenance BITE sequence are stored in the GAPCU memory.

NOTE: If all the maintenance BITE tests are completed and no fault codes are generated by any of the units, a TEST OK message is generated to the CFDIU.

(d) Stage 4 - Message conversion and storage

All the messages are transmitted to the CFDIU.

[Rev.10 from 2021] 2026.04.01 05:46:02 UTC