DC GENERATION - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
The aircraft DC power generation is provided by three Transformers Rectifiers (TR).

A. In Normal Configuration

DC Generation and Distribution - General

In normal configuration, direct current is provided by both normal transformers rectifiers (TR1 and TR2) and possibly by batteries.
TR1 supplies, through TR1 contactor (5PU1) normal bus 1 (DC BUS1), battery bus (DC BAT BUS), essential bus (DC ESS BUS) and sheddable essential bus (DC SHED ESS BUS).
The BAT BUS is supplied from BUS 1, through DC NORM BUS 1 SWITCHING contactor (1PC1), and provides power to ESS BUS and SHED ESS BUS through respectively DC ESS BUS SUPPLY contactor (4PC) and DC SHED ESS BUS contactor (8PH) in succession.
Both batteries and their respective HOT BUS are connected or not to BAT BUS, in parallel, through both BATTERY LINE contactors (6PB1 & 6PB2).
TR2 supplies, through TR2 contactor (5PU2), normal bus 2 (DC BUS 2).

B. Loss of the Transformer Rectifier 1 (TR1)

Loss of Transformer Rectifier 1 - Block Diagram

In the event of TR1 loss, DC BUS 1 and DC BAT BUS are automatically restored from TR2 through DC NORM BUS 2 SWITCHING contactor (1PC2) and DC NORM BUS 1 SWITCHING contactor (1PC1). DC ESS and SHED ESS BUSSES are automatically transferred to ESS TR through ESS TR contactor (3PE). ESS TR supply is provided from AC BUS 1 through AC ESS BUS SWITCHING contactor (3XC) and AC ESS BUS contactor (15XE) in succession. The 28VDC SHED BUSSES 210PP and 212PP are automatically shedded.

C. Loss of the Transformer Rectifier 2 (TR2)

Loss of Transformer Rectifier 2 - Block Diagram

TR2 loss leads to symmetrical recovery of DC BUS 2 from TR1; DC ESS and SHED ESS BUSSES are transferred to ESS TR through ESS TR contactor. The 28VDC SHED BUSSES 210PP and 212PP are automatically shedded.

D. Loss of the TR1 and TR2
In the event of TR1 and TR2 loss (loss of DC BUS 1 & 2), DC ESS and SHED ESS BUSSES are automatically restored from ESS TR through ESS TR contactor (3PE), from AC normal generation.

** ON A/C NOT FOR ALL

2. Component Location

DC Generation - Component Location

Spare Fuses - Component Location

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FIN I FUNCTIONAL DESIGNATION I PANELIZONEIACCESS I ATA

I I I I DOOR I REF.

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4PB11 FUSE-BAT1 120VU 212 24-38-00

4PB21 FUSE-BAT2 120VU 212 24-38-00

20PC1 FUSE 120VU 212 24-35-00

FIN	FUNCTIONAL DESIGNATION	PANEL	ZONE	ATA REF
** ON A/C NOT FOR ALL
1PB1	BCL-1		124	24-38-34
1PB2	BCL-2		124	24-38-34
** ON A/C NOT FOR ALL
1PB1	BCL-1		126	24-38-34
1PB2	BCL-2		126	24-38-34
** ON A/C ALL
2PB1	BAT-1		126	24-38-51
2PB2	BAT-2		126	24-38-51
** ON A/C NOT FOR ALL
4PB1	HOLDER-BAT 1 FUSE	120VU	212	24-38-00
4PB2	HOLDER-BAT 2 FUSE	120VU	212	24-38-00
** ON A/C ALL
6PB1	CNTOR-LINE, BAT 1	105VU	126	24-38-55
6PB2	CNTOR-LINE, BAT 2	120VU	212	24-38-55
7PB1	P/BSW-ELEC/BAT 1	35VU	210	24-38-00
7PB2	P/BSW-ELEC/BAT 2	35VU	210	24-38-00
1PC1	CNTOR-DC NORM BUS 1 SWITCHING	120VU	212	24-35-55
1PC2	CNTOR-DC NORM BUS 2 SWITCHING	120VU	212	24-35-55
4PC	CNTOR-DC ESS BUS SUPPLY	106VU	125	24-35-55
** ON A/C NOT FOR ALL
20PC	HOLDER-FUSE	120VU	212	24-35-00
** ON A/C ALL
1PE	TR-ESS		125	24-34-51
3PE	CNTOR-ESS TR	106VU	125	24-34-55
1PU1	TR-1		126	24-32-51
1PU2	TR-2		124	24-32-51
5PU1	CNTOR-TR 1	120VU	212	24-32-55
5PU2	CNTOR-TR 2	120VU	212	24-32-55
14PU	CNTOR-TR 2/AC SVCE BUS NORM SPLY	120VU	212	24-32-55
15PU	P/BSW-TR RST	103VU	126	24-32-00
3PV1	VOLTMETER-BAT 1	35VU	210	24-37-21
3PV2	VOLTMETER-BAT 2	35VU	210	24-37-21

A. Spare Fuses

(1) If fuses 4PB11 and 4PB21 blow, you can replace them by spare 350 A fuses located on the panel 120VU.

(2) If fuse 20PC1 blows, you can replace it by a spare 80 A fuse located on the panel 120VU or by a spare 80 A fuse located on the left side panel, in the cockpit.

** ON A/C NOT FOR ALL

3. BITE Test

CFDS Architecture (Liaison with TR's and BCL's)

The BITE and maintenance test of both BCL as well as maintenance test of the three TR's are controlled through the Centralized Fault Display System (CFDS).
The CFDS is composed of:

Centralized Fault Display Interface Unit (CFDIU),
two Multipurpose Control and Display Units (MCDU).

BCL's are type 2 systems, i.e. they are connected to the CFDIU with:

a discrete input used to initiate a test from CFDS,
an ARINC 429 output bus.

TR's are type 3 systems, i.e. they are connected to the CFDIU with 2 discrete links:

one of them used to send a ground signal to CFDIU in case of TR FAULT.
the other used for the reset from CFDIU.

[Rev.10 from 2021] 2026.04.01 12:41:33 UTC