24 Electrical

Dornier 328DORNIER LUFTFAHRT TRAINING MANUAL

LINE /BASE MAINTENANCE

Effectivity: - FOR TRAINING PURPOSES ONLY - Page: 24-1328-100 Mod.10 Issue: 01/96 ETM/ETX

TM-Electrical Power

ATA CHAPTER 24ELECTRICAL POWER

24-00 GENERAL 5

24-20 AC GENERATION 7GENERAL ................................................................................................................................................ 7FUNCTIONAL DESCRIPTION .............................................................................................................. 8

AC Alternator System ........................................................................................................................... 8AC Inverter System............................................................................................................................... 8

24-21 AC ALTERNATOR SYSTEM 9GENERAL ................................................................................................................................................ 9INTERFACE TO OTHER SYSTEMS ................................................................................................... 10

Indicating............................................................................................................................................. 10Emergency DC Power System ............................................................................................................ 10AC External Power.............................................................................................................................. 11Control and Dimming (Chapter 33-LIGHTS)..................................................................................... 11

FUNCTIONAL DESCRIPTION ............................................................................................................ 12Alternator 1XA-1 (1XA-2).................................................................................................................. 12Alternator control unit 2XA (12XA)................................................................................................... 13Current transformer 4XA (14XA)....................................................................................................... 13Alternator line relay 3XA (13XA) ...................................................................................................... 13

OPERATION .......................................................................................................................................... 13System characteristics LH (RH).......................................................................................................... 13

SYSTEM INDICATIONS ...................................................................................................................... 18

24-22 AC INVERTER SYSTEM 19GENERAL .............................................................................................................................................. 19INTERFACE TO OTHER SYSTEMS ................................................................................................... 20

Indicating............................................................................................................................................. 20Control and Dimming (Chapter 33 - LIGHTS)................................................................................... 20

FUNCTIONAL DESCRIPTION ............................................................................................................ 21General ................................................................................................................................................ 21Inverter 1XE, 2XE............................................................................................................................... 21

OPERATION .......................................................................................................................................... 22Power Supply ...................................................................................................................................... 23Inverter Circuit .................................................................................................................................... 23


24-30 DC-GENERATION 24GENERAL .............................................................................................................................................. 24FUNCTIONAL DESCRIPTION ............................................................................................................ 25

DC Starter/Generators ......................................................................................................................... 25Battery System .................................................................................................................................... 25Emergency DC Power System ............................................................................................................ 25

Dornier 328TRAINING MANUAL DORNIER LUFTFAHRTLINE /BASE MAINTENANCE

Page: 24-2 - FOR TRAINING PURPOSES ONLY - Effectivity:Issue: 01/96 ETM/ETX 328-100 Mod.10

TM-Electrical Power

24-31 DC STARTER/ GENERATOR SYSTEM 26GENERAL...............................................................................................................................................26INTERFACE TO OTHER SYSTEMS....................................................................................................27

Indicating (Chapter 31 - INDICATING/RECORDING SYSTEMS)..................................................27Starting (Chapter 80 - STARTING SYSTEM)....................................................................................27Engine Fire Extinguishing (Chapter 26 - FIRE PROTECTION) ........................................................28Landing Gear (Chapter 32 - LANDING GEAR).................................................................................28DC Electrical Load Distribution ..........................................................................................................28Control and dimming (Chapter 33 - LIGHTS) ....................................................................................28

FUNCTIONAL DESCRIPTION.............................................................................................................28General.................................................................................................................................................28Starter/Generator 1PC-1 (1PC-2).........................................................................................................29Generator Control Unit 2PC (12PC)....................................................................................................30Bus Power Control Unit (BPCU) 20PC...............................................................................................30Hall Effect Sensors 3PC (13PC), 4PC-1 (4PC-2)................................................................................30

OPERATION...........................................................................................................................................31Power Supply .......................................................................................................................................31Starter/Generator 1PC-1 (1PC-2).........................................................................................................31Hall Effect Sensors 3PC (13PC), 4PC-1 (4PC-2)................................................................................35DC Relay Box (1VE) ...........................................................................................................................37

SYSTEM INDICATIONS.......................................................................................................................38

24-32 BATTERY SYSTEM 39INTERFACE TO OTHER SYSTEMS....................................................................................................40

Indicating (Chapter 31 - INDICATING/RECORDING SYSTEMS)..................................................40Emergency DC Power System.............................................................................................................40DC External Power ..............................................................................................................................40DC Electrical Load Distribution ..........................................................................................................40Control and Dimming (Chapter 33 - LIGHTS) ...................................................................................40

FUNCTIONAL DESCRIPTION.............................................................................................................41General.................................................................................................................................................41Battery 1PA, 11PA...............................................................................................................................41Bus Power Control Unit 20PC.............................................................................................................41

OPERATION...........................................................................................................................................41SYSTEM INDICATIONS.......................................................................................................................42

24-33 EMERGENCY DC POWER SYSTEM 43GENERAL...............................................................................................................................................43INTERFACE TO OTHER SYSTEMS....................................................................................................44

Indicating System.................................................................................................................................44Battery system......................................................................................................................................44Functional Description.........................................................................................................................44

OPERATION...........................................................................................................................................45Power Supply .......................................................................................................................................46TRU Circuit..........................................................................................................................................46


24-40 EXTERNAL POWER 47General.................................................................................................................................................47AC External Power ..............................................................................................................................47DC external power ...............................................................................................................................47




TM-Electrical Power

24-41 AC EXTERNAL POWER 48GENERAL .............................................................................................................................................. 48INTERFACE TO OTHER SYSTEMS ................................................................................................... 49

Indicating............................................................................................................................................. 49AC Alternator System ......................................................................................................................... 49Control and Dimming (Chapter 33 - LIGHTS)................................................................................... 49

FUNCTIONAL DESCRIPTION ............................................................................................................ 49General ................................................................................................................................................ 49Ground Power Protection Unit 6XD ................................................................................................... 49

OPERATION .......................................................................................................................................... 50SYSTEM INDICATIONS ...................................................................................................................... 51

24-42 DC EXTERNAL POWER 52GENERAL .............................................................................................................................................. 52INTERFACE TO OTHER SYSTEMS ................................................................................................... 53

Indicating............................................................................................................................................. 53DC Electrical Load Distribution System............................................................................................. 53Control and Dimming (Chapter 33 - LIGHTS)................................................................................... 53

FUNCTIONAL DESCRIPTION ............................................................................................................ 54General ................................................................................................................................................ 54Bus Power Control Unit 20PC ............................................................................................................ 54

OPERATION .......................................................................................................................................... 55SYSTEM INDICATIONS ...................................................................................................................... 56

24-50 AC ELECTR. LOAD DISTRIBUTION 57GENERAL .............................................................................................................................................. 57INTERFACE TO OTHER SYSTEMS ................................................................................................... 58

Indicating............................................................................................................................................. 58Emergency DC Power System ............................................................................................................ 58Control and Dimming (Chapter 33 - LIGHTS)................................................................................... 58

FUNCTIONAL DESCRIPTION ............................................................................................................ 58OPERATION .......................................................................................................................................... 59

AC BUS1/1XP and AC BUS2/2XP (115/200 VAC Unregulated Frequency) ................................... 60AC BUS 3XP, 4XP, 5XP and 6XP (26/115 VAC Regulated Frequency) .......................................... 60


24-60 DC ELECTR. LOAD DISTRIBUTION 61GENERAL .............................................................................................................................................. 61INTERFACE TO OTHER SYSTEMS ................................................................................................... 62

Indicating (Chapter 31 - INDICATING/RECORDING SYSTEMS) ................................................. 62Control and Dimming (Chapter 33 - LIGHTS)................................................................................... 63Landing Gear (Chapter 32 - LANDING GEAR) ................................................................................ 63

FUNCTIONAL DESCRIPTION ............................................................................................................ 63General ................................................................................................................................................ 63Bus Power Control Unit 20PC ............................................................................................................ 64

OPERATION .......................................................................................................................................... 65DC MAIN BUS 1 and DC MAIN BUS 2 ........................................................................................... 66DC BUS 1/2PP and DC BUS 2/4PP ................................................................................................... 66DC EM PWR BUS 2PP/1 ................................................................................................................... 66DC NON ESS BUS 1/1PP and DC NON ESS BUS 2/5PP ................................................................ 66DC ESSENTIAL BUS 3PP................................................................................................................. 66DC HOT BUS 1/6PP and DC HOT BUS 2/7PP................................................................................. 67DC Hot Bus 7PP/1............................................................................................................................... 67



TM-Electrical Power

DC HYD SUB BUS.............................................................................................................................67Bus TIE Relay 9PP ..............................................................................................................................67DC Voltmeter 20PX, 21PX..................................................................................................................67


INDEX 69

LIST OF ILLUSTRATIONS 69




TM-Electrical Power

24-00 GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

ON

APU

FAIL

OFF

GEN-RH

TIE

V

NON-ESS1 BUS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

BUS 1 BUS 2

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU

Fig. 1 Electric Panel

This chapter contains a description of the systems which supply and distribute voltage to the AC and DCpower supply systems.

The chapter is divided into the following sub- and sub-subsystems:- DC Generation

• DC Starter-Generator System• Battery System• Emergency DC-Power System

- AC Generation• AC Alternator System• AC Inverter System

- External Power• AC External Power• DC External Power

- AC Electrical Load distribution- DC Electrical Load Distribution

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GCUALT3ø

RH

Ext.28V DCExt.115V 3ø

LHGCU

GCU GCU

GCU

GENI

GCUALT3ø

GCUGEN

II

TIE

DC TRU

AC

Hot 1 Hot 2

BUS IIBUS I

NON/BUS NON/BUSESS-BUS

BATT1

BATT2

APU

Option

Fig. 2 E

lectric Bus System

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24-20 AC

GE

NE

RA

TIO

N

GE

NE

RA

L

AC/VARIABLE115/200V~

AC/400 Hz 115/26V~

GEN1-BUS GEN2-BUSTIE

1PP 2PP 3PP 4PP 5PP

NON-ESS-BUS 1 NON-ESS-BUS 2ESSENTIAL-BUS

DC/28V

BUS I

BUS 1 BUS 2

EXT-PWR ALT.1

INV I INV II

DCAC

BUS II

ALT.2

TRU

1 XP 2 XP 3 XP115V 115V26V 26V

4 XP 6 XP 5 XP

Fig. 3 A

C G

eneration - Basic C

onfiguration



TM-Electrical Power

This section provides information on the AC Generation subsystem. The actual AC generation isprovided by two AC alternators and two static AC inverters.

The section is divided into the following sub-subsystems:- AC Alternator System- AC Inverter System

FUNCTIONAL DESCRIPTION

AC Alternator System

The AC alternator system supplies two separate three-phase AC bus-bars with 115/200 VAC via each ofits two AC alternators (ALT's). The frequency of the alternators is regulated to within 290 to 440 Hz at anengine performance of 65 to 100%.

AC Inverter System

The AC inverter system (INV) is a single-phase system and supplies a frequency-regulated voltage of26/115 VAC, 400 Hz via each of its two static inverters.

The two inverters each supply two AC bus-bars via two separate voltage outlets.




TM-Electrical Power

24-21 AC ALTERNATOR SYSTEM

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU

��BUS 1 BUS 2BUS 1

ALTERNATOR 1XA-2

ALTERNATOR 1XA-1

DC POWER CONTROL UNIT 1VE– CIRCUIT BREAKER 1XR (5XR)– 28 VDC MAIN BUS 1 (2)

AC POWER CONTROL UNIT 2VE– CIRCUIT BREAKER 5XA (15XA)– 115 / 200 VAC BUS 1 (2)– CURRENT TRANSFORMER 4XA (14XA)– ALTERNATOR RELAY 3XA (13XA)

ALT LH SWITCH / LIGHT 6XR

ALT RH SWITCH / LIGHT 3XR

ELECTRIC PANEL30PP

OVERHEAD PANEL

AVIONIC RACK RH

ALTERNATOR CONTROL UNIT 2XA

ALTERNATOR CONTROL UNIT 12XA

C/B AND RELAY PANEL 35VE– AC PWR CTL CIRCUIT BREAKER 11XX TO 16XX

Fig. 4 Parts Location - Alternator System

This section provides information on the AC alternator sub-subsystem and components. The ACalternator system serves exclusively for the power supply to the de-icing systems, the hydraulic pumps orcomponents which are heated.

The AC alternator system has two part-systems which operate fully independently.

The three-phase AC network of each alternator has 115/200 VAC.



TM-Electrical Power

The AC alternator system has the following main components:- Switch/light ALT LH 6XR (ALT RH 3XR)- Alternator 1XA-1 (1XA-2)- Alternator control unit 2XA (12XA)- Current transformer 4XA (14XA)- Alternator line relay 3XA (13XA)

FIN Component Panel Zone Access Door

6XR Switch light ALT LH 30 PP 2103XR Switch light ALT RH 30 PP 210

1XA-1 Alternator (LH) 410 412-BL1XA-2 Alternator (RH) 420 422-CL2XA Alternator control unit (LH) 210 214-EZW12XA Alternator control unit (RH) 210 214-EZW4XA Current transformer (LH) 2VE 221 221-LZF14XA Current transformer (RH) 2VE 221 221-LZF

3XA Alternator line relay (LH) 2VE 221 221-LZF13XA Alternator line relay (RH) 2VE 221 221-LZF1XR Circuit breaker 5A 1VE 221 221-LZF5XR Circuit breaker 5A 1VE 221 221-LZF5XA Circuit breaker 60A 2VE 221 221-LZF15XA Circuit breaker 60A 2VE 221 221-LZF2XP-A AC Power Control Circuit breaker 1A 35VE 221 221-PZF2XP-B AC Power Control Circuit breaker 1A 35VE 221 221-PZF2XP-C AC Power Control Circuit breaker 1A 35VE 221 221-PZF1XP-A AC Power Control Circuit breaker 1A 35VE 221 221-PZF

INTERFACE TO OTHER SYSTEMS

Indicating

The AC alternator system sends signals to the electronic indicating, caution and advisory system(EICAS). These signals are used:

- To display caution messages in the event of a system malfunction- To display digital AC power control- To indicate the status of the AC TIE by synoptics.

The caution messages are displayed on the CAS field of the primary EICAS page and on the ELEC page.Caution messages are accompanied by a single chime in the flight crew headphones and by flashing ofthe master caution switches/lights. If a caution message has an autopage facility, the appropriate systempage is armed when the CAS field caution message is acknowledged. The CAS field caution messagesare acknowledged by pushing a master caution switch/light. The armed page can then be called up on thepilot's and/or copilot's multifunction display (MFD).

Emergency DC Power System

If the DC MAIN BUS 1 and DC MAIN BUS 2 are no longer supplied with DC power from the startergenerators, it is possible to switch over to the emergency DC power system by setting the switch TRU5XB (which is covered with a guard) to one of the alternator part-systems. Thus one of the alternator part-systems is switched over to the DC ESSENTIAL BUS 3PP via the contacts of relay 6XB (or 7XB).




TM-Electrical Power

AC External Power

If the 115/200 VAC GPU is connected and switched on, the relay 7XD interrupts the switch-in controlcircuit of the two alternators.

At the same time the ALR 3XA (coil B) is supplied with voltage via the EPR 2XD, which energizes andmakes the bus-bar contact between AC BUS 1 1XP and AC BUS 2 2XP via its main contacts.

Control and Dimming (Chapter 33-LIGHTS)

The brightness or dimming regulation of the lights FAIL and OFF, inside the switch lights, is controlledwith the switch DAY-NIGHT (in field INT-LIGHT) on the overhead panel.

The lights are connected to the dimmer 2LF. A check of the lights is made with the pushbutton TESTwhich is also in the field INT-LIGHT.

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FU

NC

TIO

NA

L D

ESC

RIP

TIO

N

Alternator 1X

A-1 (1X

A-2)

A B C + -

PMGSTATOR

VR

N T1 T2 T3

STATOR

ROTOR

EXCITERFIELD

MAINSTATOR

PERMANENTMAGNET

PM

EXCITERROTOR

ROTATINGDIODEASSY

ROTORMAINFIELD

OUTPUT

3 Ø VOLTAGE SENSING

CONTROL POWER

EXCITERCURRENTCONTROL

Fig. 5 A

lternator Function




TM-Electrical Power

A parallel connection of the alternators (1XA-1 and 1XA-2), which are installed on the left and rightengine, is not possible.

The frequency is unregulated and is dependent on the variable speed of the engine. But as the cruisingflight is made at an almost constant engine speed, the AC alternator system is designed so that at thisspeed range a frequency of approximately 400 Hz is supplied.

This AC supply is provided to the AC BUS 1 and AC BUS 2.

The alternator (ALT) is a brushless three-phase generator with 115/200 VAC and an output of 20 kVA.

It has the following main components:- Main stator winding- Rotating rectifier winding- Main exciter- Permanent magnet generator.

The alternator is installed on and driven by the reduction gearbox of the engine.

A blower unit installed in the alternator makes sure the alternator is sufficiently cooled.

Alternator control unit 2XA (12XA)

The alternator control unit (ACU) provides voltage regulation, current limitation and protection of thesystem. In addition the alternator also controls the switch-in and switch-over functions.

The ACU 2XA and 12XA are installed in the Avionic Rack RH.

Current transformer 4XA (14XA)

The current transformer (CT) monitors the current status in the AC alternator system. It registers thecurrent which flows through the lines as a proportional value and triggers differential signals, overcurrentsignals and current limiting signals in the ACU 2XA (12XA). The current transformers 4XA and 14XAare installed in the AC electric control assy. 2VE.

Alternator line relay 3XA (13XA)

The alternator line relay (ALR) is a high-performance three-phase relay (interlock relay) with auxiliarycontacts. It connects the supplied alternating current to the AC BUS 1 1XP (AC BUS 2 2XP) and permits,if an alternator does not operate, the switchover of the AC BUS without voltage to the alternator which isstill in operation.

The ALR comprises two parts and has two excitation coils (A and B).

It locks in the related end position. The ALR 3XA and 13XA is installed in the electric control assy. 2VE.

OPERATION

System characteristics LH (RH)

- Rated power: 20 kVA at 12000 rpm altitudes, all power factors- Available power at 289 Hz (approx. 8670 rpm): 10 kVA (P.Fs .9) at sea level- Rated three phase voltage: 115/200 VAC- Rated frequency: 400 Hz- Power factor: 0.75 lag to 0.95 lead- Rated current: 58 A per phase- Maximum overload over 2 min.: 87 A n- Maximum overload over 5 sec.: 116 A- Short circuit current (5 sec. max): 170 to 200 A- Total harmonic content: < 3 %

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CBA

AC - BUS 1XP

1 1 1 6016XX 15XX 14XX 5XA

AC POWER CONTROL

4VE A/BSHEET 2

DATA AQUISITION UNIT 1

1 TU

SE

E 2

44A

0902

EX

T. P

OW

ER C

BA

3XA/A26

INTERLOCK

3XA/B21

CBA

SHEET 33XB(TRU)

4XACURRENT TRANSFORMERUNIT 1

NABC

1XA-12XA

ALTERNATOR 1GENERATOR CONTROL UNIT 1

4VE A/KSHEET 2

ALT. LHON/ OFF

A1

A3

6XR

21 3 4 5 6 7

4VE A/ASHEET 2

AC - BUS 2XP BUS 2 BUS 1CBA

15XA60

3XA/B30

AC POWER CONTROL1

13XX112XX

111XX

13XA/A25

INTERLOCK

SHEET 3CBA

CURRENT TRANSFORMER

UNIT 214XA

CBAN

DATA AQUISITION UNIT 2

2 TU

D E F

12XAA

12XA

GENERATOR CONTROL UNIT 2ALTERNATOR 2

1XA-2

4VE A/JSHEET 2

ALT. RHON/ OFF

3XR

A1

A3

8 8 10

Fig. 6 A

lternator Circuit




TM-Electrical Power

5XR

7XB

43

7,510XR AC

TRU 51XR

6XB

42

2XAA/SHEET 1

13XAB30

3XAB30

TIE

CLOSED

EICAS

OPEN

B1

B1B1 C2C2

C3C3

EICASEICAS

C1C1

ALTLH

7XD7XD

13XAA

25

13XAA

13XA 3XA

253XAA

263XAA

26

13XAA

13XA

25

13XAB 3XAB

3XAA

SEE 244A0902EXT.PWR2XD/D

26

B BBB

3XA

21

W S O

31265 31

W S O

217 2330

W S O

304 2128

W S O

316 25

31 32 33302928272625242322

OFF FAIL FAIL OFF TIE TIE TIETIE

31

ALTLH

ALTRH

ALTRH

B2B2

OFFOFF FAILFAIL

TIE

B3

B3B3C1 D1

D3C3

TIE

A3

A1

DAY/NIGHT

SHEET 1

12XA

B018

2XA

B018

MAIN-BUS 2 28V MAIN-BUS 1 28V

6XR3XR

2XR

2XR

ESS-BUS 3PP 28V

2LF

DAY/NIGHT

2LF

DAY/NIGHT

2LF

Fig. 7 ALR Control Circuit



TM-Electrical Power

The control of the AC alternator system is made with DC power from the DC MAIN BUS 1 and DCMAIN BUS 2.

The operation of the left and right alternator is the same. The subsequent text describes the left alternator,and the figures in brackets refer to the system components of the right alternator.

When the switch/light ALT LH 6XR (ALT RH 3XR) is pushed the white light OFF 6XX (OFF 5XX)goes off and the ALT 1 (2) is switched on.

At the same time, if the ACU 2XA (12XA) releases the switch-in, the ALR 3XA (13XA) excitation-coilA are supplied and locked via the open contacts of excitation-coil B(3 or 13XAA). The main contactsnow connect the ALT 1 (2) with the AC BUS 1 1XP (AC BUS 2 2XP) and the ALT is switched in.

If a failure is found in the system during the operation, the logic of the ACU 2XA (12XA) interrupts thevoltage to the excitation-coil A in the ALR 3XA (13XA). The light FAIL 2XW (FAIL 1XW) comes on(amber) and indicates the failure of the ALT 1 (2). Thus the AC BUS 1 1XP (AC BUS 2 2XP) is nolonger supplied.

When the switch/light TIE 2XR which belongs to the AC electrical load distribution system is pushed, theexcitation-coil B of the ALR 3XA (13XA) is supplied and locked via the closed auxiliary contacts of theexcitation-coil A. The main contacts now connect the AC BUS, which is no longer supplied, to the ALTwhich is still in operation.

The light 7XX (white) now indicates (with a bar symbol) that the TIE connection is made.

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*I *H *F *D2VEA

FHK

GC

U-C

ON

TR

OL

1D

C-G

RO

UN

DB

TC

-CO

NT

RO

L A

LT 1

FA

IL-A

LT 1

B

*E *G *C *J *Q *R *T *S *N

FA

IL-A

LT 1

BT

C-E

XT

ER

NA

LS

IGN

AL-

BT

C 1

7XX

SIG

NA

L-B

TC

7X

X

DC

-GR

OU

ND

FA

IL-A

LT 2

BT

C-C

ON

TR

OL

ALT

2F

AIL

-ALT

2S

UP

PLY

BT

C-S

INA

L

GJL

A

3XA

2VE

2VEA

2VEA 2VEB 2VEC

TRUBUS 2

15XA

2VEA

2VEA

EXT. POWER

ALT. 2

ALT. 1

13XA

5XA

BUS 1

A B C D

G

H

J

K

A

B

C C B A D

L

M

N

P

D

E

F

CURRENT-TRAFO

SENSING GCU 1

4XA*A

4XA

CONNECTOR 2VEA: MS3470W-22-55PNCONNECTOR 2VEB: MS3470W-14-4PN

CURRENT-TRAFO

SENSING GCU 2

EXTERNAL- LIGHT

EXTERNAL- SIGNAL

A

B

C

2VEA2XD

EE

*G

A

B

C

14XA*A

14XA

B A

60

B

AAB

60

C B A

4XB

2VEA

5

A

B

C

B

A

*A T U V Z W X Y *B R S *PA B C

TR

U-C

ON

TR

OL

115V

RE

SE

RV

E

GR

OU

ND

115

V

RE

SE

RV

E

TR

U-C

ON

TR

OL

115V

SU

PP

LY T

RU

GC

U-C

ON

TR

OL

2

2XB

A

15

B

8XB

5

Fig. 8 A

C R

elay Box 2V

E

The A

C relay box contains the high current alternator line relays, the external and the T

RU

relay. As

additionally features the current transformers sense the current flow

in the supply lines.



TM-Electrical Power

SYSTEM INDICATIONS

CAS FIELD Indication MFD PAGE Indication Fault or Condition

AMBER

L/R ALT FAIL

AMBER

ALT LH/RH FAIL

LH/RH Alternator off

AMBER

L/R AC VOLT FAIL -

Phase fail LH/RH Alternator

ESS–DC

BUS 1 BUS 2AC–POWER

ALT LH ALT RHTRUEXT

115 V 115 V

FAIL FAIL

FAIL

OFF

Fig. 9 AC System Indications




TM-Electrical Power

24-22 AC INVERTER SYSTEM

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU


ELECTRIC PANEL30PP

RELAY BOX 4VE– CURRENT RELAY 21XR, 26XR– RELAY 23XR, 28XR– CIRCUIT BREAKER 3XE, 4XE, 5XE, 6XE– DIODE D1, D2– CAPACITOR 24XR, 29XR

C / B SIDE PANEL RH 10VE– INV 2 CIRCUIT BREAKER 25XR– 28 VDC NON ESS BUS 2 5PP

INVERTER 2XE

INVERTER 1XE

OVERHEAD C / B PANEL 12VE– INV1 CIRCUIT BREAKER, 20XR– 28 VDC ESSENTIAL BUS 3PP

AVIONIC RACK RH

C / B PANEL 18VE– 115 VAC BUS 3XP, 5XP– 26 VAC BUS 4XP, 6XP

OVERHEAD PANEL

INV2 SWITCH / LIGHT27XR

INV1 SWITCH / LIGHT22XR

Fig. 10 Parts Location - Inverter System

This section provides information on the AC inverter (INV) sub-subsystem. The primary function of theAC inverter system is to supply the recording equipment and special navigation systems with 26/115VAC 400 Hz single phase.



TM-Electrical Power

The AC inverter system has the following main components:- Switch/light INV1 22XR, INV2 27XR- Inverter 1XE, 2XE- Current relay 21XR, 26XR- Relay 23XR, 28XR


1XE Inverter 1 221 222-AZF2XE Inverter 2 221 222-AZF3XE Circuit breaker 1A 4VE 221 221-BZF4XE Circuit breaker 2A 4VE 221 221-BZF5XE Circuit breaker 1A 4VE 221 221-BZF6XE Circuit breaker 2A 4VE 221 221-BZF

20XR Circuit breaker INV 1/7,5 A 12VE 21021XR Current relay 1 4VE 221 221-BZF22XR Switch light INV LH 30PP 21023XR Relay 1 4VE 221 221-BZF24XR Capacitor 1 4VE 221 221-BZF25XR Circuit breaker INV 2/7,5 A 10VE 21026XR Current relay 2 4VE 221 221-BZF27XR Switch light INV RH 30PP 21028XR Relay 2 4VE 221 221-BZF29XR Capacitor 2 4VE 221 221-BZF

D1 Diode 1 4VE 221 221-BZFD2 Diode 2 4VE 221 221-BZF


Indicating

The AC inverter system sends signals to the electronic indicating, caution and advisory system (ECIAS).These signals are used:

- To display caution messages in the event of a system malfunction- To display digital AC power control.

The caution messages are displayed on the CAS field of the primary EICAS page and on the ELEC page.Caution messages are accompanied by a single chime in the flight crew headphones and flashing mastercaution switches/lights. If a caution message has an autopage facility, the appropriate system page isarmed when the CAS field caution message is acknowledged. CAS field caution messages areacknowledged by pushing a master caution switch/light. The armed page can then be called up on thepilot's and/or copilot's multifunction display (MFD).

Control and Dimming (Chapter 33 - LIGHTS)

The brightness or dimming of the lights FAIL and OFF, inside the switch lights, is controlled with theswitch DAY-NIGHT (in field INT-LIGHT) on the overhead panel.

The lights are connected to the dimmer 2LF.

A check of the lights is made with the pushbutton TEST which is also installed in the field INT-LIGHT.

The lights are switched on via the diode U1.




TM-Electrical Power


General

During normal operation two static inverters supply the 26 V and 115 V/400 Hz to the AC consumers.The output has a stabilized voltageand frequency.Each of the two identical INV supply two AC bus-barsvia two outputs.When one of the INVs (1XE or 2XE) malfunctions, the relay 23XR or 28XRautomatically switches to the AC voltage supply of the INV which is still in operation. The relays 23XRand 28XR are controlled by the fault monitor output of the respective inverter.

Inverter 1XE, 2XE

The 125 VA static inverter converts DC electrical power into single phase, sinewave, regulated ACelectrical power. The nominal input DC power is 28 V and the nominal outputs of the INV are 115 VACand 26 VAC.The generation of the alternating signal and the regulation are accomplished by a singleintegrated regulating pulse width modulator circuit. The quasi-square wave output of the integrated circuitis amplified and filtered by a tuned transformer to provide a low distortion sinewave output. The outputsignal is used for both current and voltage sensing circuits to provide the necessary information to theregulating control circuits of the integrated circuit. The INVs are installed internally under the floorassembly in the fuselage.

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OP

ER

AT

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FAIL OFF

OFF ON

EICAS 1TUB/A011

22XR

23XR

C2

C3

4VV

24XR +

23XR X1

X2

1XE

A1

A2

115V

B1

B2

B323XR

3A3

26V

3XE 4XE1 2

1 1

22

3 XP 4XP

1TUDAU 1

115V 26V

AC MASSE

5 6 7 8 94321 10 11 12 13

INV 1

2

13

5

21XR

D2

OFF OND2 D1

D3

22XR

2LF

DAY/NIGHT

20XR7,5 INV 1

ESS - BUS 3PP

PHASE LOCK

NON - ESS - BUS 2 5PP

7,5

2LF

DAY/NIGHT

25XR

2 INV 2

OFF ONA1 A2

A3

27XR

D1

3

5

26XR2

1

115V 26V

FA

UL

TM

ON

ITO

RFA

UL

TM

ON

ITO

R

INV 2

A1A3

A2

B3 B1

B228XR

21

5XE 6XE1 21 1

22

J K5XP 6XP

115V 26V

11TUDAU 2

AC MASSE

161514

FAILOFF

OFFON

EICAS 11TUB/A011

27XR

28XR

C2

C321

+29XR

X1

X2

SEE 331A090242vv/1F

LAMP TEST

1817 19 20 21 22 23

S O 14 1416 16

23

S O 9 9

11 112

2XE

Fig. 11 Inverter C

ircuit




TM-Electrical Power

Power Supply

Component BUS Circuit Breaker No.

Power Supply Inverter 1 ESS 3PP INV 1 20XR

Power Supply Inverter 2 NON ESS 2 5PP INV 2 25XR

Inverter Circuit

The INVs are identical in operation. Thus only the INV 1XE is described.

When the switch/light INV1 22XR is pushed, ground is connected to the remote ON/OFF circuit and theINV 1XE is switched on. If the output voltage and the frequency of the INV are within the tolerance, theoutput voltage of the fault monitor energizes the coil of relay 23XR. The relay 23XR switches the outputvoltage (115 VAC and 26 VAC/400 Hz) to the AC-BUS 3XP and AC BUS 4XP. At the same time thewhite light OFF 8XX goes off. The AC BUS 5XP and AC BUS 6XP are supplied by the INV 1XE aslong asthe relay 28XR is de-energized and the INV 2XE is not switched on.

If the INV 1XE malfunctions, the output voltage of the fault monitor is zero. The relay 23XR is de-energized and disconnects the faulty INV from the AC BUS 3XP and 4XP. At the same time the amberlight FAIL 3XW comes on, and the de-energized relay 23XR connects the AC BUS 3XP and 4XP to thevoltage supply of the INV 2XE. If the cause of the inverter failure is in the AC voltage supply network,the INV is switched off by an internal switching circuit.

If there is a short circuit of the AC system in the AC electrical load distribution system, the increasedcurrent on the DC side energizes the current relay 21XR (> 6A). The closed contacts prevent the de-energizing of the relay 23XR until the circuit breaker on the AC side is opened.The capacitor 24XRprovides a drop-out delay-function.

SYSTEM INDICATIONS


AMBER

INV 1/2 FAIL

AMBER

Inverter 1/2 - FAIL

Inverter off

AMBER

INV-BUS 1/2 FAIL

AMBER

Bus Synoptic

Indicates inverter buses status

INV 1

115 V 26 V 26 V 115 V

INV 2FAIL FAIL

Fig. 12 Inverter System Indications

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24-30 DC

-GE

NE

RA

TIO

N

GE

NE

RA

LEXT GEN I GEN II APU (OPTION)

GEN

GEN ICONT

GEN IICONT

BATT ICONT

BATT IICONT

GEN 1-BUS GEN 2-BUS

BATT IHOT-BUS I HOT-BUS II

BATT II6PP

2PP 3PP 4PP 5PP

7PP

NON-ESS1CONT

NON-ESS2CONT

NON-ESS-BUS 1 NON-ESS-BUS 2ESSENTIAL-BUSBUS I BUS II

1PP

TIE

EXTCONT

GENCONT

GCU GCUG G GCUGFig. 13 D

C G

eneration - Basic C

onfiguration




TM-Electrical Power

This section provides information on the DC generation subsystem.

The DC power supply is provided by two DC starter/generators.

Two batteries charged with generator voltage also supply additional DC current. If the two DCstarter/generators fail, a transformer/rectifier unit supplies the most important DC consumers.

The chapter is divided into the following sub-subsystems:- DC starter/generator- Battery system- Emergency DC power system

Fig. 15 gives an overview over DC Voltage supply and distribution. It must be considered that relays,monitored by the electronic units of the electrical system, control the (dis-)connection of buses undsuppliers.


DC Starter/Generators

The starter/generator system, with each of its two starter/generators (S/G), provides a separate DC MAINBUS with 28.5 VDC.

The bus TIE relay, which is open during normal operation, permits the parallel operation of the two SGswhen in the closed condition.

At the same time the relay connects the bus-bars and ensures the supply from one of the S/Gs.

Battery System

The battery system has a buffer function in the DC power supply (with operation of the two S/Gs) andstabilizes it in the event of alternating loads. At the same time the batteries make sure that there is alimited 24 VDC supply in the event that the S/Gs malfunction.


The emergency DC power system makes sure, with the aid of the transformer/rectifier unit (TRU)supplied from the 115 VAC power supply, that there is a 28 VDC supply to the DC ESSENTIAL BUS3PP.



TM-Electrical Power

24-31 DC STARTER/ GENERATOR SYSTEM

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU��

BUS 1 BUS 2BUS 1

STARTER / GENERATOR1PC-2

DC POWER CONTROL UNIT 1VE– CIRCUIT BREAKER 6PC, 7PC, 8PC (16PC, 17PC, 18PC)– HALL EFFECT SENSOR 3PC (13PC)– GENERATOR LINE RELAY 5PC (15PC)– 28 VDC MAIN BUS 1 (2)– CIRCUIT BREAKER 2PR, 5PR

ELECTRIC PANEL30PP

AVIONIC RACK LH

BUS POWER CONTROL UNIT 20PC

HALL EFFECT SENSOR 4PC-2

HALL EFFECT SENSOR 4PC-1

STARTER / GENERATOR1PC-1

GEN LH SWITCH / LIGHT21PC

OVERHEAD PANEL

GENERATORCONTROL UNIT 12PC

GENERATORCONTROL UNIT 2PC

OVERHEAD C / B PANEL 12VE– 28 VDC BUS 1 2PP– 28 VDC BUS 2 4PP– CIRCUIT BREAKER GCU1 / 9PC (GCU2 / 19PC)

GEN RH SWITCH / LIGHT 22PC

Fig. 14 Parts Location - Generator System

This section provides information on the DC starter/generator sub-subsystem and components.

The left and right hand engine-mounted starter/generators (S/Gs) supply the primary power supply forstarting the engines (Chapter 31 - STARTING SYSTEM) and the 28.5 VDC supply to the DC electricalload distribution systems.




TM-Electrical Power


21PC GEN LH Switch/Light 30PP 21022PC GEN RH Switch/Light 30PP 2101PC-1 Starter/Generator (LH) 410 412-CR1PC-2 Starter/Generator (RH) 420 422-BR2PC Generator Control Unit (LH) 210 213-DZW12PC Generator Control Unit (RH) 210 213-DZW3PC Hall Effect Sensor (LH) 1VE 221 221-LZF13PC Hall Effect Sensor (RH) 1VE 221 221-LZF4PC-1 Hall Effect Sensor (LH) 4104PC-2 Hall Effect Sensor (RH) 4205PC Generator Line Relay (LH) 1VE 221 221-LZF15PC Generator Line Relay (RH) 1VE 221 221-LZF20PC Bus Power Control Unit 210 213-DZW6PC Circuit Breaker 3A 1VE 221 221-LZF7PC Circuit Breaker 15A 1VE 221 221-LZF8PC Circuit Breaker 3A 1VE 221 221-LZF16PC Circuit Breaker 3A 1VE 221 221-LZF17PC Circuit Breaker 15A 1VE 221 221-LZF18PC Circuit Breaker 3A 1VE 221 221-LZF9PC GCU 1 Circuit Breaker 10A 12VE 21019PC GCU 2 Circuit Breaker 10A 12VE 2102PR Circuit Breaker 10A 1VE 221 221-LZF5PR Circuit Breaker 10A 1VE 221 221-LZF


Indicating (Chapter 31 - INDICATING/RECORDING SYSTEMS)

The DC starter/generator system sends signals to the electronic indicating, caution and advisory system(EICAS). These signals are used to display caution and warning messages in the event of a systemmalfunction:

- To display caution messages in the event of a system malfunction- To display digital DC power control- To indicate the status of the DC TIE by synoptics.

The caution messages are displayed on the CAS field of the primary EICAS page and on the ELEC page.Caution messages are accompanied by a single chime, warning messages by a triple chime and flashingmaster caution switches/lights.

If a caution message has an autopage facility, the appropriate system page is armed when the CAS fieldcaution message(and warning messages on the red warning panel) is acknowledged. Theacknowledgement is performed by pushing a master caution switch/light. The armed page can then becalled up on the pilot's and/or copilot's multifunction display (MFD).

Starting (Chapter 80 - STARTING SYSTEM)

When the start procedure is initiated, the GLR 5PC (15PC) is energized by the GCU 2PC (12PC), and therelated S/G 1PC-1 (2) on the engine LH (RH) operates as a starter. The start procedure is regulated by thespeed sensing circuit of the GCU via a sensor which is installed in the S/G. It supplies signals which areproportional to the generator speed.



TM-Electrical Power

When the N1-rotational speed of 5400 + 100 rpm is reached the start procedure is completed.

Engine Fire Extinguishing (Chapter 26 - FIRE PROTECTION)

If the fire extinguishing procedure on the left (right) engine is triggered, the control and excitation of theS/Gs operation as a generator is interrupted by the pushbutton ENG LH FIRE 2WB (ENG RH FIRE42WB).

Landing Gear (Chapter 32 - LANDING GEAR)

The relay 32GA supplies the GCU 2PC (12PC) and the relay 31GA of the BPCU 20PC with controlsignals via the air/ground operation of the DC starter/generators. They interrupt the procedure switchingfor the external voltage supply on the ground.

DC Electrical Load Distribution

The digital voltmeters 20PX and 21PX installed in the FIELD ELECTRIC (on the overhead panel) permita check of the generator voltage supplied to the DC MAIN BUS 1 and DC MAIN BUS 2.

Control and dimming (Chapter 33 - LIGHTS)

The brightness or dimming of the lights in the switch/lights GEN LH and GEN RH, is controlled by theswitch DAY-NIGHT (in field INT-LIGHT) on the overhead panel.

The lights are connected to the dimmer 2LF.




General

During normal operation each starter/generator (1PC-1 and 1PC-2) supplies a separate DC MAIN BUS.Parallel to each of the two S/Gs a battery is also connected into the circuit (see 24-32-00).

When the normally-open bus TIE relay 9PP is in the closed position it permits the parallel operation ofthe two S/Gs (with a differential current of ± 10%). At the same time it also connects the bus-bars DCMAIN BUS 1 and DC MAIN BUS 2 and permits the supply from one of the two S/Gs. Both the voltageand the current of the two S/Gs are independently controlled and regulated by a separate GCU (2PC and12PC). The aircraft power supply is regulated to 28.5 VDC.

The bus-power control-unit 20PC (BPCU) which is installed in the system, has the function to monitorthe current and voltage so that if any malfunctions occur (overload or short circuit) the defective DC busbar is disconnected from the power supply.




TM-Electrical Power

Starter/Generator 1PC-1 (1PC-2)

+

-

A

E

D

123

Thermalprotection

Red Mark White Mark

Speed Sensor

S/G

EICAS

Fig. 15 Starter/Generator

When the four-pole starter/generator (S/G) 30 V/400 A with interpoles, compensating- and shunt-windings functions as a starter it has an increased shunt-effect, and when it functions as a generator it hasa decreased shunt-effect. Four sets of two carbon brushes, positioned behind each other, make sure thatthe load is correctly distributed. Each of the carbon brushes is equipped with a stop which limits the wear,and also avoids damage to the collector.

A speed- and temperature-sensor installed in the S/G provides signals.

The S/G is mounted on the high-speed section (drive gearbox) of the respective engine. The S/G issupplied with adequate cooling air via a ram-air connection located in the engine cowling doors.



TM-Electrical Power

A mounting adaptor, which is installed between the engine and the S/G, permits the outlet of the coolingair and the installation of the air deflection tube. On the ground, an installed fan ensures adequate cooling.

The flexible torsion-driveshaft with damper compensates for any unusual effects which occur on the driveside.

A pre-determined break-point (18,4 mkg) protects against excessive torque.

The starter/generator thermal protection contact closes when the temperature of the winding reaches165.5°C and an appropriate visual indication shows up on OHP,CAS Field and System Page. At 149.5°Cnormal operation is reinstalled.

Generator Control Unit 2PC (12PC)

The generator control unit (GCU) controls and protects the starter/generator. The voltage of the shuntgenerators is regulated by field weakening through the GCU and is kept constant independent of therotational speed. In addition, the GCU has the following protective function during the starter andgenerator operation:

Starting Phase- Speed sensing circuit- Field weakening- Overspeed protection- Starter relay control and automatic starter cut-out- Starter-control failure-annunciation

Generating Mode- DC voltage regulation- Load sharing during parallel operation- Generator current limiting- Generator line relay control- Overvoltage protection- Ground fault protection- Excess-excitation protection- Excess-current protection- Undervoltage protection- Reverse polarity protection- Supply mode of main functional circuits- Remote electrical reset, remote electrical trip and anti-cycle protection- Self-test.

The generator control units (GCUs) 2PC and 12PC are installed in the Avionic Rack (LH).

Bus Power Control Unit (BPCU) 20PC

The BPCU is installed in the avionic rack LH and monitors the current and voltage ratio of the DC busbars. If an overload or short circuit occurs it disconnects the defective DC bus from the aircraft powersupply. In addition it also connects control signals and regulates the function of the two starter /generators.

Hall Effect Sensors 3PC (13PC), 4PC-1 (4PC-2)

The hall effect sensors (HECS) provide differential protection for the current pickoffs from the S/G to theGCU.

The HECS are connected in the negative and also in the positive line-circuits, and when ground is appliedthey switch off the S/G.

At the same time they also measure the generator current.

The HECS 3PC and 13PC are installed in the DC power control unit 1VE, while 4PC-1 is installed on theleft engine and 4PC-2 on the right engine.




TM-Electrical Power

OPERATION

Power Supply


Power Supply GCU 1 BUS 2 4PP GCU 1 9PC

Power Supply GCU 2 BUS1 2PP GCU2 19PC

Starter/Generator 1PC-1 (1PC-2)

Starter Performance

- Maximum input current: 1700 A with return to 1400 A within 1.5 sec.

Generator Performance

- Rated terminal voltage : 30 VDC- Rated load current : 400 A- Rated Output: 12kW (400 A - 30V DC)- Rated Speed Range:7200 to 12300 rpm- Overload Current:600 A during 2 minutes, 800 A during 8 sec's.- Overspeed:14000 rpm during 2 minutes

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OVHT

S / G

D

A

Sp

E (-)

4PC-1

1PC-1

2PC

A1

A2

B (+)

1PC

-1* A

1TUDAU 1

GENERATORCONTROL

UNIT 1

LOADSHARING

20PC

BUS-POWER-CONTROL

UNIT

A2

A1

1VE*A

BB

3PC

36PC

157PC

1TUDAU 1

1TUA

5PC

8PC

SHEET 2/19

31PP 2PP

MAIN-BUS 1

4PR

12PP150A

11PP150A

1019PC

GCU 2

SH

EE

T 2

/19

3PA

1TUDAU 1

2WWWARNPANEL

16 A038

2WW*A

1TUB

6PP

1PA

*B

SHEET 2/23

1023PC

BPCU

500A 2PA

1PA*A(-)

10PP-A

1PA

OV

HT

BATT 1

(+)1PA*A

12VV-313PP150A

OVHT

S / G

D

A

Sp

E (-)

4PC-2

1PC-2

A1

A2

B (+)

1PC

-2* A

11TUDAU2

A2

A1

*W

13PC

316PC

1517PC

11TUDAU2

15PC

18PC

SHEET 2/40

35PP4PP

MAIN-BUS 2

7PR

15PP150A

1024PC

BPCU

13PA

11TUDAU 2

2WWWARNPANEL

21 A038

2WW*A

11TUB

7PP

11P

A*B

109PC

GCU 1

500A 12PA

11PA*A(-)

11PA

OV

HT

BATT 2

(+)11PA*A

16PP150A

10PP-B

TIE

9PP

ESSENTIAL-BUS 3PP

SHEET 2/38

CROSS-STARTSTART

START INITn>61,5 %

END OF LOADSHEDINHIB. GCUOVERLOAD

GEN.1 BUS GEN.2 BUS

GENERATORCONTROL

UNIT 2

12PC

LOADSHARINGZ

1VE*A

1VE*BTIE

9PP

YAPU-GCU, A008001A491A0901, SHEET 1

G

14PP150A

18VE

Fig. 16 Starter/G

enerator System




TM-Electrical Power

The operation of the left and right starter/generator is identical. The subsequent text describes theoperation of the left starter/generator. The figures in brackets refer to the system components of theright starter/generator.

The S/G 1PC-1 (1PC-2) is ready for operation when the switch/light GEN LH/21PC (GENRH/22PC) is pushed. The white light OFF/3PX (OFF/4PX) contained in the switch/light comes on aslong as the GLR 5PC (15PC) is not energized, or the pole-reversal procedure from starter operationto generator operation is not completed. When the required engine rpm(N3 = 7380 ± 60 rpm) isreached, and all the protection and regulation functions in the GCU 2PC (12PC) are correct, the GLR5PC (15PC) is then energized. It now connects the generator voltage to the DC MAIN BUS 1(DCMAIN BUS 2) and the OFF light goes off.

The voltage (28,5 VDC) of the shunt-wound generator is regulated by field weakening through theGCU and is kept constant independent of the rotational speed.

In addition the BPCU 20PC monitors the current and voltage condition in the system and that of theDC bus bar.

If the S/Gs malfunction (overvoltage, excess or reverse current, or complete failure) the GCU 2PC(12PC) disconnects the defective generator from the DC MAIN BUS 1 (DC MAIN BUS 2). At thesame time the amber light FAIL 3PW (FAIL/4PW) comes on.

When the related switch/light TIE 1PR for the DC electrical load distribution system is pushed, thebus TIE relay 9PP is energized via the BPCU 20PC. It makes sure there is parallel operation ofthetwo S/Gs or that there is a series connection (between the DC MAIN BUS 1 and DC MAIN BUS2) if one of the generators fails. The white light 6PX shows the TIE connection is made bydisplaying a bar-symbol.

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B079

1TUDAU 1

2LF

SHEET 1/11

23PC

10BPCU

A2 A1 B2 B1 C1

C3B3A3GEN LHWOW

D3 D1

32GAD2

1TUB

B3B1

15PDB2

FIRE

E

19PC

21PX -

+V

1TUB

B

B

GCU 210

BUS 1=2PPSEE A280A0901 SHT.2

1TUDAU 1 S

HE

ET

1/3

MAIN BUS 1

38PC

19 20 21 22 23 24

5PC

2PC 20PCBPCUGCU 1

10PP

25 26 27 28

A1 B1 B3A3

A2 B29XB

5XB

A1A3

A2

B1 B3

B2

WOW WOW

31GA

A1A3

A2

B1 B3

B27PD

6PP MAIN - BUS 1 6PP 7PP

2PR

10 5 5

4PA 14PABATT. 1 BATT. 2

1TUDAU 1

2LF

BATT. 1 BATT. 2

FA

IL

FA

IL

OF

F

OF

F

OF

F

NON ESS. 1 B3 A3

A1B1

3PR 5PA 15PA

A3 B3 C3

A1 B1 C1

4PR

NON ESS. 1 BATT. 1

C2

C3

D2

D3

3PDDC/EXT

C3 B3 A3

C1 B1 A1

2LF

PANEL LIGHT23PX

22PX

2LF1TU

DAU 111TUDAU 2

3

8PR

DCTIEIND

3PP

TIE

1PR

A3 B3

A1 B1

9PP20PC

BATT. 220PCBPCU

-

+

+

4PR3PA

TIE

TRU

13PA+-

+

-

+

-

+

-

+

-

+

-

+9PP

29 30 31 32 33 34 35

W S D

320

23 23

11

GEN LH

W S D W S D

1224 24

1627 27

CHANGE OVER

S D W S D W S D W S D

52628

2628

NON ESS. 1 BATT. 1 BATT. 2

9 122929

2920

3333

3320

14

3535

143535

TIESEE SHEET 1

SEE 001A244A0901SEE 001A801A0901

FA

IL

OFF

Fig. 17 D

C P

ower M

onitoring System




TM-Electrical Power

Hall Effect Sensors 3PC (13PC), 4PC-1 (4PC-2)

_

+I

d UH

Fluxdensity B

Hall-Effect

UH = RH . I . Bd

X

Fig. 18 Hall Effect Current Sensor

CONDITIONINGCIRCUITRY

POWERSUPPLY( DC GCU)

OUTPUT VOLTAGE( PROPRTIONAL TOLINE CURENT)

HALL EFFECT SENSOR

IDC

Fig. 19 HECS Schematic



TM-Electrical Power

HECS are made from very thin semiconductor material (5µm to 10µm) which is vacuum metalized onceramic waver plates. With a voltage supplied to the plate, a current is flowing. An additional magneticfield causes the electrons to move towards one side of the plate. Thus a voltage, dependant on force anddirection of the magnetic field, can be measured.

In the case of the Do 328 the magnetic field is caused by the current flowing on the plus and minus sideof the generator. The measured hall voltage indicates size and direction of the actual current and is usedby the GCU for monitoring and by the EICAS for indication purposes.

Do

rnier 328

DO

RN

IER

LU

FT

FA

HR

TT

RA

ININ

G M

AN

UA

LLIN

E /B

AS

E M

AIN

TE

NA

NC

E

Effectivity:

- FOR

TR

AIN

ING

PUR

POSE

S ON

LY

-P

age: 24-37328-100 M

od.10Issue: 01/96 E

TM

/ET

XT

M-E

lectrical Power

DC

Relay B

ox (1VE

)

EX

T-P

OW

ER

GE

NE

LH

BA

TT

1

BA

TT

2

GE

NE

RH

AP

U

BU

S 1

NO

N-E

SS

BU

S 1

ES

S B

US

ES

S B

US

BU

S 2

NO

N-E

SS

BU

S 2

51XR

38PC

10 2PR

PPBB*F

1VE

A

EB

1VE

C + -

-

+

4PR

11PP150A

1VEA

*E NN *G *I *D *J *K

12PP150A

5PD

- 5PC

+

1VE

+

-

AA *V *X *T MM *U *Y *W Y R P *Z A

1VEA 1VEC

3PC

A B C D F G E

A B C D F G E

7PC

6PC

15

3

A B C D E F L M G J H N K T U S *C

1VEA

+ -REV.

1VEA

3PA

+ -REV.

13PA

*A V X W *B **K

*M *J *N

1VEB 1VEB

*H *C *E *D *G C B *S

- 15PC

+

13PC

A B C D F G E

A B C D F G E

17PC

16PC

15

3

1VEC 1VEB

D E F G H J *Y A K L M *Z *XC

10

5PR

*T*U*W*V

1VE

B

D

1VE

C

18PC 5XR

3 5

10PP-A10PP-B

-

+

-

+

*H *M *N *Q *R *S

1VEA150A13PP

9PP

150A16PP

1VEA 1VEB150A

14PP150A

15PP

7PR

CC

EE

GG JJ KK Z

HH LL FF

DD *P Y R U T N P *F S

*AV

XWHHZ*B

-

+

1VE

B

Fig. 20 D

C -

Relay B

ox 1VE



TM-Electrical Power

The DC relay box contains as DC electrical heart all high power relays and some additional features likethe HECS in the plus line and the reverse current protection. The energizing controls are connected withthe GCU or BPCU.

SYSTEM INDICATIONS


AMBER

L/R DC GEN FAIL

AMBER

GEN LH/RH FAIL

Generator off

AMBER

L/R DC GEN OVHT

AMBER

GEN LH/RH OVHT

Generator off

200 A

GEN LH BATT 1 EXT APU BATT 2

200 A

GEN RH

NON–ESS1 1 2 NON–ESS2

ESSENTIAL28.5 V 28.5 V

DC–POWER

FAIL

OVHT

FAIL

OVHTOFF

Fig. 21 Generator System Indications




TM-Electrical Power

24-32 BATTERY SYSTEM

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU��BUS 1 BUS 2BUS 1

DC POWER CONTROL UNIT 1VE– BATTERY RELAY 3PA, 13PA– 28 VDC MAIN BUS 1 (2)

ELECTRIC PANEL30PP

AVIONIC RACK LH


BAT1 SWITCH / LIGHT5PA

OVERHEAD PANEL

BAT2 SWITCH / LIGHT, 15PA

FUSE 2PA

BATTERY 1PA

BATTERY 11PA

BATTERY JUNCTION BOX LH 6VE– DC HOT BUS 1 6PP– BAT1 CIRCUIT BREAKER, 4PA

BATTERY JUNCTION BOX RH 7VE– DC HOT BUS 2 7PP– BAT2 CIRCUIT BREAKER, 14PA

FUSE 12PA

Fig. 22 Parts Location - Battery System

This section provides information on the battery sub-subsystem and components. If the DCstarter/generators malfunction, two internal batteries take over the part-supply of the DC electrical loaddistribution system.

In addition (if a ground power unit is not available) they can also be used to start the engines.



TM-Electrical Power

The battery system has the following main components:- Switch/light BAT 1/5PA, BAT2/15PA- Battery relay 3PA, 13PA- Battery 1PA, 11PA- Bus power control unit 20PC.


5PA Switch light BAT 1 30PP 21015PA Switch light BAT 2 30PP 2103PA Battery relay (1) 1VE 221 221-LZF13PA Battery relay (2) 1VE 221 221-LZF1PA Battery (1) 130 131-BL11PA Battery (2) 130 132-BR20PA Bus power control unit 210 213-DZW4PA Circuit breaker 5A 6VE 130 131-BL14PA Circuit breaker 5A 7VE 130 132-BR2PA Fuse 150A 130 131-BL12PA Fuse 150A 130 132-BR



According to Chapter 24-31


If the two S/Gs fail when operating as generators, and the switch TRU 5XB is pushed, the triggering ofthe battery relays (3PA or 13PA) which is applied during normal operation from the BPCU 20PC isoverridden.

The triggering of the relays is then switched directly via the switch/light EXT 3PD and the switch TRU5XB to the DC HOT BUS 1/6PP and DC HOT BUS 2/7PP.

DC External Power

If the aircraft DC power supply comes from an external GPU and the switch/light EXT 3PD is switchedon, the triggering of the battery relay 3PA and 13PA (for safety reasons) is interrupted. Thus the Battery1PA and 11PA (if switched on) are automatically disconnected from the DC MAIN BUS 1 and DCMAIN BUS 2.

DC Electrical Load Distribution

The digital DC voltmeters 20PX and 21PX installed in the overhead panel (field ELECTRIC) permit acheck of the battery voltage supplied to the DC MAIN BUS 1 and DC MAIN BUS 2.


According to Chapter 24-31




TM-Electrical Power


General

The battery (1PA and 11PA) is wired in parallel to each of the S/Gs and is connected to the related DCMAIN BUS via the battery relay (BAT RLY).

The battery system is monitored by the BPCU 20PC.

The batteries are charged during the operation of the two S/Gs and function as a buffer for the DC powersupply and also stabilize the electrical load.

The reverse-current protection-devices installed in the battery relays prevent excess charging. The batterybus bars (DC HOT BUS 1 and 2) are connected directly to the batteries and supply the most importantfunctions and systems to avoid losses in case of a failure in the DC power supply.

Battery 1PA, 11PA

Two identical nickel cadmium batteries (BAT) 24 V/40 Ah are installed in the aircraft. The mainterminals are fitted with quick-release connectors.

A bi-metal thermostat is fitted to each battery and controls the temperature. The battery covers are airtightand pressure vented.

The batteries are located in the forward section of the left and right landing gear nacelles.

Bus Power Control Unit 20PC

The BPCU monitors the current and voltage status of the DC bus bars and if an overload or short circuitoccurs it disconnects the defect DC bus bar from the power supply. In addition it monitors the batteryvoltage and controls the battery relays.

OPERATION

When the batteries (1PA and 11PA) are connected, battery voltage is supplied to the DC HOT BUS 1/6PPand DC HOT BUS 2/7PP.

If the switch/lights BAT1/5PA and BAT2/15PA are in the de-energized condition (both the batteries arenot connected to the DC MAIN BUSES) the white lights OFF/61PX and OFF/2PX in the switch/lightscome on.

When the switch/light BAT1 and BAT2 are pushed the battery switching is triggered. The control voltagewhich is connected by the contacts of the switch/lights is supplied via the BPCU 20PC and theswitch/light TRU 5XB to the battery relay 3PA and 13PA. Both relays are energized and connect via theirmain contacts the battery 1PA and 11PA to the related DC MAIN BUS.

At the same time the relay contacts also connect the control circuits for the battery monitoring inside theBPCU 20PC.

If generator excess voltage occurs when the two S/Gs are operating as generators (normal operation),reverse current flows from the related DC MAIN BUS to the battery. When the maximum limit-valuesare reached the battery relay (triggered by the installed reverse-current protection-device) disconnects thebattery from the DC MAIN BUS. Immediately after the malfunctioning S/G is switched off, thedisconnected battery is connected again. If an overload occurs on one of theDC bus-bars, the BPCU 20PCalso interrupts the battery connection, or the overloaded DC bus-bar.

If a malfunction occurs in the battery system, the amber light FAIL 1PW or FAIL 2PW (in the relatedswitch/light) comes on and shows that a malfunction or disconnection of the battery has occurred.

When one of the two batteries (1PA or 11PA) is overheated as a result of overload, the temperatureswitch installed in the related battery is closed. A voltage signal is now connected and causes the lightBATT LH OVHT (BATT RH OVHT) in the red warning panel 2WW to come on, and the EICAS systemis actuated.



TM-Electrical Power

SYSTEM INDICATIONS


AMBER

BATT 1/2 FAIL

AMBER

BATT 1/2 FAIL

Battery 1/2 disconnected from main bus

-

RED

BATT 1/2 OVHT

Battery overheat warning at 71°C

GEN LH BATT 1 EXT APU BATT 2 GEN RH

DC–POWER

200 A 200 A 200 A



FAIL

OVHT

FAIL

OVHTOFF

Fig. 23 Battery System Indications




TM-Electrical Power

24-33 EMERGENCY DC POWER SYSTEM

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU��

BUS 1 BUS 2BUS 1

ELECTRIC PANEL30PP

RELAY BOX 4VE– RELAY 6XB, 7XB, 9XB

OVERHEAD C / B PANEL 12VE– TRU CIRCUIT BREAKER 10XR– FUSE 10XB– 28 VDC ESSENTIAL BUS 3PP

OVERHEAD PANEL

TRANSFORMERRECTIFIER UNIT 1XB

AC POWER CONTROL UNIT 2VE– CIRCUIT BREAKER 2XB, 4XB, 8XB– SUPPLY RELAY 3XB

TRU SWITCH 5XB

Fig. 24 Parts Location - TRU System

This section provides information on the Emergency DC Power sub-subsystem and components.



TM-Electrical Power

The transformer rectifier unit (TRU) 1XB is supplied from the three phase frequency-regulated 115/200VAC aircraft power supply, and supplies the DC ESSENTIAL BUS 3PP with 28 VDC if the two DCgenerators fail.

The supply procedure is made with the guarded switch TRU 5XB on the overhead panel. The transformerrectifier unit (TRU) is installed under the floor assembly in the fuselage.

The Emergency DC Power System has the following main components:- Switch TRU 5XB- Transformer rectifier unit 1XB- Supply relay 3XB- Relay 6XB, 7XB, 9XB


5XB Switch TRU 30PP 2101XB Transformer Rectifier Unit 221 221-JZF3XB Supply Relay 2VE 221 221-JZF6XB Relay 4VE 221 221-BZF7XB Relay 4VE 221 221-BZF9XB Relay 4VE 221 221-BZF4XB Circuit Breaker 5A 2VE 221 221-JZF8XB Circuit Breaker 5A 2VE 221 221-JZF2XB Circuit Breaker 15A 2VE 221 221-JZF10XR Circuit Breaker AC-TRU/7,5 A 12VE 21010XB Fuse 150 A 12VE 210


Indicating System

The Emergency DC Power System sends signals to the electronic indicating, caution and advisory system(EICAS). The caution and status messages are displayed on the ELEC page.

Battery system

When the switch TRU 5XB is operated, the control circuit to the battery relay 3PA or 13PA is switchedover at the same time.

Thus the BPCU 20PC is overridden and the control switched directly to the related DC HOT BUS 1 orDC HOT BUS 2.

Functional Description

The transformer rectifer unit (TRU) is a static inverter which converts three phase AC electrical powerinto an unregulated 28 VDC.

The maximum output of the transformer is 150 A.

An air ventilator which operates with a variable rotation speed ensures a constant heat dissipation.

The supply relay (3XB) is a high-performance (interlocking) relay which also has auxiliary contacts.With its main contacts it supplies AC electrical power to the TRU (transformer rectifier unit) 1XB.

Do

rnier 328

DO

RN

IER

LU

FT

FA

HR

TT

RA

ININ

G M

AN

UA

LLIN

E /B

AS

E M

AIN

TE

NA

NC

E

Effectivity:

- FOR

TR

AIN

ING

PUR

POSE

S ON

LY

-P

age: 24-45328-100 M

od.10Issue: 01/96 E

TM

/ET

XT

M-E

lectrical Power

OP

ER

AT

ION

ESSENTIAL-BUS 3PP

A B

B16XBA1

B17XBA1

INTERLOCKX1 X1

X2 X23XB 6XB 7XB 3XBC

40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55

4XB

A B

TRU

1A 1B

5XB3A 2A 2B 3B

56XB

5

W 51 51 51

S 48

O S 27 41

O 27

S 21 44

O 21

W 51 51 51

S 47

O S

O *25 *26

9XBX1

X2

44H

G

3XBB 41E

D

3XBA

SEE SHEET 2

10XR1

2AC TRU

150A

10XB

1

27,5

SEE SHEET 1

A

B

C

A

B

C

SEE SHEET 1

3XBA 41 3XBB44

2XB15

AC

DC

1XBTRU

28V/DC

+ -

EICAS

Fig. 25 T

RU

Circuit



TM-Electrical Power

Power Supply


TRU Circuit ESS 3PP AC TRU 10XR

TRU Circuit

The supply relay is a two-part relay and is equipped with two excitation coils (A and B). It locks in therespective end position.

When the guarded switch TRU 5XB is set to one of the AC alternator part-systems which is in operation(1 or 2), the Emergency DC Power System is switched on.

The relay 6XB (or 7XB) is supplied with 115 VAC (Phase C) and is energized.

It connects via its contacts the voltage supply to the supply relay 3XB and at the same time switches oneof the AC alternator part-systems to the DC ESSENTIAL BUS 3PP.

When the excitation coil A (or B) is supplied with AC electrical power from the supply relay 3XB, itsmain contacts supply three phase AC electrical power to the transformer rectifier unit (TRU) 1XB.

At the same time the auxiliary contacts of relay 9XB are energized, which automatically interrupt thesupply to the change-over relay 10PP-A and 10PP-B (within the DC Electrical Load Distribution).

Thus the DC ESSENTIAL BUS 3PP is disconnected from the DC bus-bar network.

The 28 VDC supplied by the TRU 1XB is now supplied as an emergency voltage to the DC ESSENTIALBUS 3PP.

Additionally the DC supply for the AC system is switched to the ESSENTIAL BUS 3PP.

SYSTEM INDICATIONS


-

AMBER

TRU FAIL

No power from TRU




TM-Electrical Power

24-40 EXTERNAL POWER

General

This section provides information on the External Power Sub-system.

The connection of the AC-GPU is made via the external power plug located on the left side near the mainlanding gear, and the connection of the DC-GPU via the external power plug located on the fuselage nosesection.

The External Power chapter is divided into the following sub-subsystems:- AC external power- DC external power

AC External Power

AC external power supplies the 115V/400Hz AC Bus 1/2 during maintenance work or AC tests onground.

DC external power

The DC external power supplies the DC electrical load distribution system during maintenance work orstarting preparations on the ground.

In addition the DC external power is used to supply the AC-inverters and also for starting the engines.



TM-Electrical Power

24-41 AC EXTERNAL POWER

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU

��

BUS 1 BUS 2BUS 1

ELECTRIC PANEL30PP

C/B PANEL, RACK RH 18VE– AC EXT CIRCUIT BREAKER 3XD– 28 VDC BUS 2 4PP

OVERHEAD PANEL

RELAY BOX 4VE– RELAY 7XD

GROUND POWERPROTECTION UNIT6XD

AC EXTERNAL POWER PLUG 1XDA– CIRCUIT BREAKER 4XD

AC POWER CONTROL UNIT 2VE– AC EXTERNAL POWER RELAY 2XD– 115 / 200 VAC BUS 1 1XP

EXT SWITCHLIGHT5XD

Fig. 26 Parts Location - AC External

The AC external power supply has the following main components:- Switch/light EXT 5XD- Ground power protection unit 6XD




TM-Electrical Power

- AC external power relay 2XD- Relay 7XD- AC external power plug 1XD.


5XD Switch light EXT 30PP 2106XD Ground power protection unit 221 221-BZF2XD AC-external power relay 2VE 221 221-LZF7XD Relay 4VE 221 221-BZF1XD AC-external power plug 130 131-CL4XD Circuit breaker 50A 130 131-CL3XD Circuit breaker AC EXT/5A 18VE 210


Indicating

The AC external power system sends a signal to the electronic indicating, caution and advisory system(EICAS). The signal is used to display system status messages. The status messages are displayed on theELEC page.

AC Alternator System

When the electrical supply comes from an external GPU, the relay 7XD interrupts the control circuit ofthe two alternators.

The switching of the bus-bar connection is made by the ALR 3XA in the AC alternator system.


The brightness or dimming of the lights in the switch/light EXT is controlled by the switch DAY-NIGHT(in field INT-LIGHT) on the overhead panel. The light is connected to the dimmer 2LF.


General

This section provides information on the AC external power supply sub-subsystem and components.

The three-phase ground-power unit (GPU) is connected via the AC external power plug 1XD. Only thefrequency unstable AC power supply network is supplied with 115/200 VAC, 400 Hz. The switch-in ofthe external AC-GPU to the AC BUS 1/1XP and AC BUS 2/2XP can only be made when the DC-GPU isconnected and switched on. The switch-in of the battery voltage is prohibited for safety reasons (batterydischarge).

Ground Power Protection Unit 6XD

The ground power protection unit (GPPU) protects against phase reversal, overvoltage and undervoltage.

When the safety parameters are fulfilled, the control switching is released. The unit is installed under thefloor assembly.



TM-Electrical Power

OPERATION

A

N

X

X

X

X

X

A B C

C3 B3 A3

1

2

C2 B2C1 A2B1 A1

K L

X

A B C E F

BC

M

H

F N

J D

X1

X

X

H

G

P13 1514 16

R

X

A

X2 B

SIEHE 242A1000

E

C

D

10 11 1298

6XD

7XD

7XD

2XD

3XA

2XD

2XD2XX 3XX

U1

2LF

EICAS

5XD

4PP

3XD

2XD

4XD

1XD

76 16 17 18 19 20 21151413

W S O8 16

16

S O15 0

018

Fig. 27 External AC Circuit Diagram

It is assumed that the DC-GPU supplies the DC electrical load distribution system, and that the AC-GPUis switched on and ready for operation.

If no phase reversal, overcurrent or undercurrent occurs, the GPPU 6XD releases the control for theswitch-in. The green light AVAIL 3XX comes on.

When the switch/light EXT 5XD is pushed, the external AC electrical power supply is switched on.

The relay 7XD is energized and connects the control circuit to the AC EPR 2XD which is also energized.In addition the AVAIL light goes off. The main contacts of the energized AC-EPR now connect thesupplied external 115/200 V, 400 Hz to the AC power supply network, while the auxiliary contacts makethe bus-bar connection (via ALR 3XA) to the AC-BUS 1/1XP and AC-BUS 2/2XP.

Also connected via the auxiliary contacts is the blue light ON 2XX, which indicates the switched oncondition of the external AC electrical power supply.




TM-Electrical Power

SYSTEM INDICATIONS

ESS–DC

BUS 1 BUS 2AC–POWER

ALT LH ALT RHTRUEXT

115 V

ON

115 V115 V

115 V115 V115 V

Fig. 28 External AC Indications



TM-Electrical Power

24-42 DC EXTERNAL POWER

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU


ELECTRIC PANEL30PP

AVIONIC RACK LH


EXT SWITCH / LIGHT3PD

OVERHEAD PANEL

DIODE 6PD, 11PD, 12PD,13PD, 14PD

DC EXTERNAL POWERPANEL 25VE– SWITCH / LIGHT 10PD– CONTROL CIRCUIT BREAKER 8PD

DC POWER CONTROL UNIT 1VE– DC EXTERNAL POWER RELAY 5PD– 28 VDC MAIN BUS 1– BATTERY RELAY 3PA, 13PA

RELAY SUPPORT 5VE– RELAY 7PD, 15PD

FUSE 2PD

DC EXTERNAL POWERPLUG 1PD

FUSE 16PD

Fig. 29 Parts Location - External DC System




TM-Electrical Power

The DC external power system has the following main components:- Switch/light EXT 3PD- Bus power control unit 20PC- DC external power relay 5PD- DC external power plug 1PD- Switch/light 10PD- Relay 7PD, 15PD.


3PD Switch Light EXT 30PP 2105PD DC-External Power Relay 1VE 221 221-LZF1PD DC-External Power Plug 123 123-BL10PD Switch Light 25VE 123 123-BL7PD Relay 5VE 21015PD Relay 5VE 21020PC Bus Power Control Unit 210 213-DZW8PD Circuit Breaker 5A 25VE 123 123-BL2PD Fuse 400A 123 211-MZF16PD Fuse 400A 123 211-MZF6PD Diode 25VV-2 123 211-LZF11PD Diode 25VV-2 123 211-LZF12PD Diode 25VV-1 123 211-LZF13PD Diode 25VV-1 123 211-LZF14PD Diode 25VV-1 123 211-LZF


Indicating

The DC external power system sends a signal to the electronic indicating, caution and advisory systems(EICAS). The signal is used to display system status messages. The status messages are displayed on theELEC page.

DC Electrical Load Distribution System

For information concerning the further supply and switch on of the auxiliary bus-bars 1PP, 2PP, 3PP, 4PPand 5PP refer to the DC electrical load distribution system.

The external voltage supplied to the DC MAIN BUS 1 and DC MAIN BUS 2 is indicated by the digitalDC-voltmeters 21PX and 20PX which are integrated in the overhead panel (Field ELECTRIC).


The brightness or dimming of the lights in the switch/light EXT 3PD is controlled by the switch DAY-NIGHT (in field INT-LIGHT) on the overhead panel. The light is connected to the dimmer 2LF.

A check of the lights is made with the puhbutton TEST installed in the field INT-LIGHT. The lights areswitched on via the diode U1.



TM-Electrical Power


General

This section provides information on the DC External Power Sub-subsystem and components.

The 28 VDC GPU is connected to the DC external power plug 1PD.

When the DC external power system is operated the autonomous power supply is switched off and thepriority is given to the external power system. The bus TIE relay 9PP automatically makes the bus-barcontact between the DC MAIN BUS 1 and DC MAIN BUS 2.


The BPCU protects the DC electrical power supply against overvoltage and incorrect polarity when anexternal power source is connected

Do

rnier 328

DO

RN

IER

LU

FT

FA

HR

TT

RA

ININ

G M

AN

UA

LLIN

E /B

AS

E M

AIN

TE

NA

NC

E

Effectivity:

- FOR

TR

AIN

ING

PUR

POSE

S ON

LY

-P

age: 24-55328-100 M

od.10Issue: 01/96 E

TM

/ET

XT

M-E

lectrical Power

OP

ER

AT

ION

BUS PROTECTION/CONTROL UNIT

DATA AQUI UNIT(EICAB)SIG 522 (DC EXT.POWER STATUS)

5PD

4749

48

AVAIL

ONONNOT USED

50 U1

11PX12PX13PX10PX

2LF

20PC

15PD

13PD

14PD

11PD

10PDLT

5PD

2PD

6PD8PD1PD

EXT.

12PD

7PD

MAIN-BUS 13 PA

5PD

13 PA

+

-

10 11 12987 16 17 18 19 20151413

W S O171940

W S O716

16 16

W S O2425

A1E

E

A2A1

500AA2

X1

X2

A2

A1

X1

X2 A3

B1

B2

Fig. 30 E

xternal DC

Circuit D

iagram



TM-Electrical Power

If there is no overvoltage or incorrect polarity (when the DC GPU is connected and switched on) theBPCU 20PCU releases the control for the switch-in. At the same time the relay 7PD is energized which,when the aircraft is without electrical power (if the proximity sensor electronic unit 6GA is not supplied),permits the switch-in of the GPU.

The green light AVAIL 11PX comes on. In addition, the annunciator NOT USED 10PX located in theswitch/light 10PD (25VE) comes on.

It provides optical indication that the aircraft's own power supply is not switched on.

If the switch/light EXT 3PD is now pushed, the two batteries and the two S/Gs, if switched in, aredisconnected from the DC MAIN BUS 1 and DC MAIN BUS 2. The de-energized contacts of the batteryrelay 3PA and 13PA connect the positive control to the EPR 5PD. The negative control now switches inthe BPCU 20PC. The energized EPR now switches with its main contacts the 28 VDC external powersupply to the DC MAIN BUS 1 via the fuse 2PD (600A). At the same time, via auxiliary contacts, therelay 15PD is energized which interrupts the supply circuit to the light AVAIL and permits the whiteannunciator ON 12PX (and annunciator ON 13PX) to come on. The latter indicate the switched incondition of the DC electrical load distribution system.

The bus TIE relay 9PP, which belongs to the DC electrical load distribution system, automaticallysupplies the DC MAIN BUS 2 (controlled by the BPCU 20PC). The switch/light 10PD located on the DCexternal panel 25VE permits, when pushed, a check of all the annunciators which are installed in it.

The switching off procedure of the GPU must only be made after the aircraft's own system has beenswitched off, when the S/Gs are going to take over the supply.

As a result, the annunciator NOT USED 10PX located on the DC external panel 25VE must come on.Thus a disconnection in the event of an excessive load is prevented.

SYSTEM INDICATIONS

ON

28.1 V

GEN LH BATT 1 EXT APU BATT 2

0 A

GEN RH


ESSENTIAL28.1 V

DC–POWER

0 A

Fig. 31 External DC System Indications




TM-Electrical Power

24-50 AC ELECTR. LOAD DISTRIBUTION

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU

��

BUS 1 BUS 2BUS 1

ELECTRIC PANEL30PP

RELAY BOARD 4VE– RELAY 23XR, 28XR

OVERHEAD C / B PANEL 12VE– TRU CIRCUIT BREAKER 10XR

OVERHEAD PANEL

C / B AND RELAY PANEL 35VE– 115 / 200 VAC BUS 1 1XP– 115 / 200 VAC BUS 2 2XP

DC POWER CONTROL UNIT 1VE– 28 VDC MAIN BUS 1 (2)– CIRCUIT BREAKER 1XR, (5XR)

C / B PANEL 18VE– 115 VAC BUS 3XP– 26 VAC BUS 4XP– 115 VAC BUS 5XP– 26 VAC BUS 6XP

AC POWER CONTROL UNIT 2VE– ALTERNATOR LINE RELAY 3XA (13XA)

TIE SWITCH / LIGHT 2XR

Fig. 32 Parts Location - AC Distribution

This section provides information on the AC electrical load distribution sub-system. The system isdivided into a three-phase frequency-unregulated 115/200 VAC (290-440 Hz) bus-bar network and asingle-phase frequency-regulated 26/115 VAC (400 Hz) bus-bar network.



TM-Electrical Power

The AC electrical load distribution system has the following main components:- AC BUS 1/1XP and AC BUS 2/2XP (115/200 VAC frequency-unregulated)- AC BUS 4XP and AC BUS 6XP (26 VAC frequency-regulated)- AC BUS 3XP and AC BUS 5XP (115 VAC frequency-regulated)- Switch/light TIE 2XR.


1XP AC Bus 1 115/200 V AC 35VE 221 221-PZF2XP AC Bus 2 115/200 V AC 35VE 221 221-PZF4XP AC Bus 26 V AC 18VE 2106XP AC Bus 26 V AC 18VE 2103XP AC Bus 115 V AC 18VE 2105XP AC Bus 115 V AC 18VE 2102XR Switch Light TIE 30PP 210


Indicating

The AC electrical load distribution system sends signals to the electronic indicating, caution and advisorysystem (EICAS).

The signals are used:- display caution messages in the event of a system malfunction (AC bus-bars synoptics)- to display the status of the AC TIE by synoptics.

Note:

A detailed description of the system malfunctions indicated in the CAS-field (primary EICAS page) is notgiven here, refer to the related system description

The caution messages are displayed on the ELEC page. The status of the AC bus-bars is shown by bus-bar synoptics. Different colours are used to indicate the status:

- amber indicates an abnormal status- green indicates a normal status.


If the TRU 1XB is switched on after the malfunction of the two S/Gs, the relay 6XB (or 7XB) isenergized. This relay now switches the AC alternator part-system to the DC ESSENTIAL BUS 3PP.


The brightness or dimming of the lights in the switch/light TIE, is controlled by the switch DAY-NIGHTS (in field INT-LIGHT) on the overhead panel. The lights are connected to the dimmer 2LF.




The supply of the frequency-unregulated bus-bar network is achieved via two AC alternators, and thesupply of the frequency-regulated bus-bar network is achieved by two AC inverters supplied on the inputside with DC voltage.

Do

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DO

RN

IER

LU

FT

FA

HR

TT

RA

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AN

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LLIN

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AS

E M

AIN

TE

NA

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Effectivity:

- FOR

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ING

PUR

POSE

S ON

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age: 24-59328-100 M

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TM

/ET

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M-E

lectrical Power

On the ground the frequency-unregulated bus-bar netw

ork can be supplied directly with 115/200 V

AC

from a G

PU via the A

C external pow

er plug.

The supply of the frequency-regulated bus-bar netw

ork on the ground can only be achieved on the inputside w

ith 28 VD

C.

OP

ER

AT

ION

A

B

C

1P

BUS 1

D

INTERLOCK INTERLOCK

EXT POWERA B C D

A BC DA B

C

2XP

BUS 2

A

B

C

ALT. 1~

GCUTRU ALT. 1

~

GCU

Fig. 33 A

C D

istribution



TM-Electrical Power

AC BUS1/1XP and AC BUS2/2XP (115/200 VAC Unregulated Frequency)

During normal operation, the two AC alternators (1XA-1 and 1XA-2) supply the two three-phase ACbus-bars (AC BUS1 and AC BUS2). If one of the ALTs malfunctions, the AC bus which is no longersupplied can be switched to the ALT which is still in operation via the switch/light TIE 2XR. When theCoil B of the ALR 3XA (or 13XA) is energized, after pushing the switch/light TIE (supplied by thecontacts of Coil A), the corresponding ALR (3XA or 13XA) now makes the bus-bar connection. Thewhite light 7XX (in switch/light) now indicates with a bar-symbol that the TIE connection is made.

The AC bus-bars of the aircraft's frequency-unregulated AC power supply, and the related circuitbreakers, are located in the C/B and relay panel 35VE.

AC BUS 3XP, 4XP, 5XP and 6XP (26/115 VAC Regulated Frequency)

During normal operation the two AC inverters (1XE and 2XE) supply the two AC bus-bars with differentvoltages (26 V and 115 V, 400 Hz).

If one of the INV malfunctions there is an automatic switchover, of the AC bus-bar which is no longersupplied, to the INV which is still in operation.

If there is a reduction of the DC-voltage on the DC NON ESS BUS2/5PP, the INV 1XE which is stillsupplied from the DC ESSENTIAL BUS 3PP takes over the supply of the AC BUS 3XP, 4XP, 5XP and6XP ((DMC D1-A-24-22-00-00Y-099Y-A). The AC bus-bars of the frequency-regulated AC powersupply, and the related circuit breakers, are located in the C/B panel 18VE.

SYSTEM INDICATIONS

ESS–DC

BUS 2AC–POWER

ALT LH ALT RHTRUEXT

0 V 115 V

OFF

BUS 1

Fig. 34 AC Distribution Indications

INV 1

V 26 V 26 V 115 V

INV 2

0

Fig. 35 Inverter Distribution Indications




TM-Electrical Power

24-60 DC ELECTR. LOAD DISTRIBUTION

GENERAL

FAIL

OFF

GEN-LH

FAIL

OFF

BAT 1

AVAIL

ON

EXT

FAIL

OFF

BAT 2

FAIL

OFF

GEN-RH

TIE

V

NON-ESS 1

DC

ESSENTIAL

OFF

ELECTRIC

BUS 2 NON-ESS 2

OFF

FAIL

OFF

ALT LH

FAIL

OFF

ALT RH

TIE

AVAIL

ON

EXT

AC

FAIL

OFF

INV 1

FAIL

OFF

INV 2

115V 115V26V 26V

TRU��

BUS 1 BUS 2BUS 1

ELECTRIC PANEL30PP

OVERHEAD C / B PANEL 12VE– 28 VDC BUS 1 2PP– 28 VDC BUS 2 4PP– 28 VDC EMERG PWR BUS 2PP / 1– 28 VDC EMERG PWR BUS 2PP / 2– 28 VDC ESSENTIAL BUS 3PP– 28 VDC HYD SUB BUS– DC TIE IND CIRCUIT BREAKER 8PR

OVERHEAD PANEL

DC POWER CONTROL UNIT 1VE– 28 VDC MAIN BUS 1 (2)– BUS TIE RELAY 9PP– CHANGE OVER RELAY 10PP-A / 10PP-B– NON ESS BUS RELAY 4PR, 7PR– CIRCUIT BREAKER 2PR, 5PR– FUSES 11PP, 12PP, 13PP, 14PP, 15PP,16PP

C / B SIDE PANELRH / 10VE– 28 VDC NON ESS BUS 2 5PP– NON ESS 2 IND CIRCUIT BREAKER 2PX

SWITCH / LIGHT 6PR (NON ESS 2)

AVIONIC RACK LH

BUS POWER CONTROL UNIT20PC

DC VOLTMETER 20PX

DC VOLTMETER21PX

SWITCH / LIGHT 3PR(NON ESS 1)

TIE SWITCH / LIGHT 1PR

C / B SIDE PANELLH / 11VE– 28 VDC NON ESS BUS 1 1PP– NON ESS 1 IND CIRCUIT BREAKER 1PX

BATTERY JUNCTION BOX LH 6VE– DC HOT BUS 1 6PP– BPCU CIRCUIT BREAKER 23PC

BATTERY JUNCTION BOX RH 7VE– DC HOT BUS 2 7PP– BPCU CIRCUIT BREAKER 24PC

C/B AND RELAY PANEL 36VE– DC HCT BUS 7PP/1 (DISPLAYS)

Fig. 36 Parts Location - DC Distribution

This section provides information on the DC Electrical Load Distribution Sub-system. The system is afunction-related sub-system of the 28 VDC electrical power system.



TM-Electrical Power


DC MAIN BUS 1 1VE 221 221-LZFDC MAIN BUS 2 1VE 221 221-LZF

DC HYD SUB BUS 12VE 2101PP DC NON ESS BUS 1 11VE 2105PP DC NON ESS BUS 2 10VE 2102PP DC BUS 1 12VE 2104PP DC BUS 2 12VE 210

2PP/1 DC EM PWR BUS 12VE 2102PP/2 DC EM PWR BUS 12VE 2103PP DC ESSENTIAL BUS 12VE 2106PP DC HOT BUS 1 6VE 130 131-BL7PP DC HOT BUS 2 7VE 130 132-BR

7PP/1 DC HOT BUS (Displays) 36VE 221 221-PZF9PP BUS TIE Relay 1VE 221 221-LZF

10PP-A Changeover Relay 1VE 221 221-LZF10PP-B Changeover Relay 1VE 221 221-LZF

4PR NON ESS BUS Relay 1VE 221 221-LZF7PR NON ESS BUS Relay 1VE 221 221-LZF1PR Switch/Light TIE 30PP 2103PR Switch/Light (NON ESS 1) 30PP 2106PR Switch/Light (NON ESS 2) 30PP 21021PX DC-Voltmeter LH 30PP 21020PX DC-Voltmeter RH 30PP 21020PC BUS Power Control Unit 1VE 210 213 DZW5PR Circuit Breaker 10A 1VE 221 221-LZF2PR Circuit Breaker 10A 12VE 221 221-LZF8PR Circuit Breaker TIE IND 3A 7VE 21024PC Circuit Breaker BPCU 10A 6VE 130 132-BR23PC Circuit Breaker BPCU 10A 1VE 130 131-BL11PP Fuse 150A (1PP) 1VE 221 221-LZF12PP Fuse 150A (2PP) 1VE 221 221-LZF13PP Fuse 150A (3PP) 1VE 221 221-LZF14PP Fuse 150A (4PP) 1VE 221 221-LZF15PP Fuse 150A (5PP) 1VE 221 221-LZF16PP Fuse 150A (3PP) 1VE 221 221-LZF1PX Circuit Breaker NON ESS 1 IND 11VE 2102PX Circuit Breaker NON ESS 2 IND 10VE 210



The DC electrical load distribution system sends signals to the electronic indicating, caution and advisorysystem (EICAS).

The signals are used:




TM-Electrical Power

- to display caution messages in the event of a system malfunction (DC bus-bars synoptics)- to indicate the status of the DC TIE by synoptics- to display digital DC power control.

Note:

A detailed description of the system malfunctions indicated in the CAS-field (primary EICAS page) is notgiven here, refer to the related system description

The caution messages are displayed on the ELEC page. The status of the DC bus-bars is shown by bus-bar synoptics. Different colours are used to indicate the status:

- amber indicates an abnormal status- green indicates normal status.


The brightness or dimming of the lights in the switch/lights 3P3, 6PR

(NON ESS 1 and 2) and the switch/light TIE 1PR is controlled by the switch DAY-NIGHT (in field INT-LIGHT) on the overhead panel.

This also applies for the synoptic presentation DC ESSENTIAL bus in the field ELECTRIC. Theannunciators and lights are connected to the dimmer 2LF. A check of the lights can be made with thepushbutton TEST which is also installed in the field INT-LIGHT. The annunciators and lights areswitched on via the diode U1.

Landing Gear (Chapter 32 - LANDING GEAR)

The relay 31GA supplies control signals to the BPCU 20PC about the air or ground operation of theaircraft. It also interrupts the priority switching for the external voltage supply on the ground. In additionthe relay 7PD also permits (when the aircraft is without voltage or when the proximity-sensor electronic-unit 6GA is not supplied) the APU to be switched on.

- Rated output: 12 kW (400 A -30 VDC)- Rated speed range: 7200 to 12300 rpm- Overload current: 600 A during 2 min.800 A during 8 sec.- Overspeed: 14000 rpmduring 2 min.


General

The supply of the DC MAIN BUS 1 and DC MAIN BUS 2 (with the related DC bus-bars) is achievedwith 28 VDC from the starter/generators with the batteries switched on. The batteries also act as a pufferand stabilize the aircraft's power system while they charge at the same time. When the S/Gs are switchedoff, the aircraft's 24 VDC power supply can be provided for a short time by the batteries.

In addition, if the two S/Gs malfunction, a TRU enables the emergency supply of the DC ESSENTIALBUS 3PP. In the event of a complete failure of the system, the DC HOT BUS 1 and DC HOT BUS 2 takeover the supply of the emergency systems.

Note:

The battery voltage consumed during maintenance work on the ground (or when starting the engines)must be reduced to a minimum, in order to prevent battery discharge.

The consumers are connected to five DC bus-bars via circuit breakers.

Each of the auxiliary bus-bars is protected by a 150 A fuse.

In addition the BPCU 20PC monitors the current and voltage in the system in order to switch off theoverloaded DC bus in the event of a malfunction.

On the ground the aircraft's DC power supply can be achieved via a GPU.



TM-Electrical Power


With the aid of its electronics the BPCU monitors the current and voltage in the system. It switches all thecurrent and voltage signals in the correct sequence. The control signals have the following functions:

- Switch on of the batteries- Control of the TIE relay 9PP- Control of Changeover Relay 10PP-A, 10PP-B (see DC ESSENTIAL BUS 3PP)- Control of Non-Ess Bus Relay 4PR, 7PR (see DC NON ESS BUS 1 and 2)

In addition the BPCU automatically triggers switching procedures which, according to the supply of theDC electrical load distribution system, ensure the connection of the bus-bars. The BPCU, controlled bythe relay 31GA on the landing system, also recognizes whether the aircraft is operating on the ground orin the air and interrupts the priority operation of the external power supply.

If overloading or short circuits occur on one of the bus-bars, or if a malfunction occurs, the fault islocalized and the defective DC bus is switched off. The load-shedding is made after a reaction time of 3-4seconds (for the fuses) and the relays are switched off in a pre-determined sequence (0,3 second cycle).

If the supply of the distribution system is made on the ground by a DC GPU the BPCU 20PC protectsagainst reverse polarity and overvoltage.

The BPCU is installed in the LH avionic rack.




TM-Electrical Power

OPERATION

Fig. 37 DC Distribution



TM-Electrical Power

DC MAIN BUS 1 and DC MAIN BUS 2

The DC MAIN BUS 1 and DC MAIN BUS 2 is the central supply point for the system. All power-generating and power-consuming systems are connected via these bus-bars. The DC MAIN BUS 1supplies the DC NON ESS BUS 1/1PP, the DC BUS 1/2PP and the DC EM PWR BUS 2PP/1.

The DC MAIN BUS 2 supplies the DC BUS 2/4PP and the DC NON ESS BUS 2/5PP. The supply of theDC ESSENTIAL BUS 3PP can be made either from the DC MAIN BUS 1 or from the DC MAIN BUS 2or, if a voltage failure occurs, from the 28 VDC emergency supply (TRU 1XB). The DC MAIN BUS 1and DC MAIN BUS 2 are installed in the DC Power Control Unit 1VE.

DC BUS 1/2PP and DC BUS 2/4PP

The DC Bus 1 is permanently connected via the fuse 12PP (150 A) with the DC MAIN BUS 1, and theDC Bus 2 is connected via the fuse 14PP (150 A) with the DC MAIN BUS 2. If a malfunction of one ofthe two starter generators occurs, they must remain supplied. Both of the two DC bus-bars and the relatedcircuit breakers are installed in the overhead C/B panel 12VE.

DC EM PWR BUS 2PP/1

During emergency operation (when the aircraft's DC voltage supply fails) the DC EM PWR BUS suppliesthe necessary NAV-systems from the Emergency Power Supply 2FM. During normal operation theemergency power supply (emergency battery) is charged by the DC BUS 1/2PP.

The DC EM PWR BUS is installed in the overhead C/B panel 12VE.

DC NON ESS BUS 1/1PP and DC NON ESS BUS 2/5PP

The DC NON ESS BUS 1 and DC NON ESS BUS 2 can be switched off and operated manually via theswitch/lights 3PR and 6PR. In the switched off condition the white lights OFF 17PX and OFF 18PX bothcome on.

If both switch/lights are pushed, the Non-Ess Bus-Relay 4PR and 7PR are energized via a function of theBPCU 20PC. They now connect via their contacts the related DC NON ESS BUS with the respective DCMAIN BUS 1 or 2.

The white bar-symbol 7PX and 8PX contained in the switch/lights now indicate that the bus-barconnection has been made.

If one of the two S/Gs malfunctions, the related DC NON ESS BUS is automatically switched off(controlled by the BPCU 20PC). When the bus TIE relay 9PP is connected, the DC NON ESS BUS isswitched on again. Thus for a short transition period the battery is protected against the supply ofelectrical power to unimportant consumers. When both of the two S/Gs malfunction and with the bus TIErelay 9PP connected, the two batteries supply in parallel the DC MAIN BUS 1 and DC MAIN BUS 2.The DC NON ESS

BUS 1 and DC NON ESS BUS 2 are now switched off. The DC NON ESS BUS 1 and the related circuitbreakers are installed in the C/B side-panel LH/11VE and the DC NON ESS BUS 2 in the C/B side-panelRH/10VE.

DC ESSENTIAL BUS 3PP

The DC ESSENTIAL BUS is supplied from the DC MAIN BUS 1 or DC MAIN BUS 2 (via theChangeover Relay 10PP-A or 10PP-B). The Changeover Relays (CHOR) are controlled by the BPCUwhich, according to the voltage situation, always switches to the DC MAIN BUS which is operatingoptimally.

If both of the two S/Gs or their voltage supplies malfunction, the DC ESSENTIAL BUS can be suppliedwith 28 VDC emergency power from the TRU 1XB.




TM-Electrical Power

The DC ESSENTIAL BUS is then disconnected from the DC MAIN BUS 1 and DC MAIN BUS 2 (bythe Changeover Relay). The bus-bar symbol with the text ESSENTIAL, which is displayed in the fieldELECTRIC, is illuminated by the amber lights 22PX, 23PX and stays on as long as the voltage supply isconnected. The DC ESSENTIAL BUS and the related circuit breakers are installed in the overhead C/Bpanel 12VE.

DC HOT BUS 1/6PP and DC HOT BUS 2/7PP

The battery bus-bars are connected directly to the batteries. They supply the emergency systems if a totalfailure occurs. Both the batteries are charged via the battery relays 3PA and 13PA with 28.5 VDC (fromthe starter/generators) and are protected against reverse current. The DC HOT BUS 1 and the relatedcircuit breakers are installed in the battery junction box LH/6VE and the DC HOT BUS 2 is installed inthe battery junction box RH/7VE.

DC Hot Bus 7PP/1

This bus is connected via a fuse to the DC HOT BUS 2 and supplies the displays during engine start.

DC HYD SUB BUS

The HYD BUS is normally supplied by the ESS BUS or in case of a malfunction by BUS 1 via relay24DA.

Bus TIE Relay 9PP

The bus TIE relay 9PP, which is installed between the DC MAIN BUS 1 and the DC MAIN BUS 2, isopen when both of the two starter/generators are operating normally. The white bar-symbol 16PXcontained in the switch/light TIE 1PR indicates the disconnected condition of both DC MAIN BUSES. Ifthe switch/light is pushed, the bus TIE relay 9PP is energized via the BPCU 20PC. Thus the paralleloperation of both of the S/Gs or, in the event of the malfunction of one of the S/G, the restoration of thesupply to the malfunctioning DC MAIN BUS is achieved.

The white bar-symbol 6PX, contained in the switch/light TIE, shows that the bus-bar connection has beenmade.

If both of the two S/Gs malfunction, the bus TIE relay is also energized and both the batteries supply inthe parallel the DC MAIN BUS 1 and DC MAIN BUS 2. The bus TIE relay 9PP is installed in the DCPower Control Unit 1VE.

DC Voltmeter 20PX, 21PX

The DC digital voltmeters (DC VMTR) installed in the overhead panel 30PP (Field ELECTRIC) showthe DC voltage which is applied to the DC MAIN BUS 1 and DC MAIN BUS 2.



TM-Electrical Power

SYSTEM INDICATIONS


AMBER

DC BUS 1 FAIL

AMBER

Synoptic DC Bus 1

Indicates status of DC BUS 1

AMBER

DC BUS 2 FAIL

AMBER

Synoptic DC Bus 2

Indicates status of DC BUS 2

AMBER

ESS BUS FAIL

AMBER

Synoptic ESS Bus

Indicates status of ESS BUS

200 A

GEN LH BATT 1

OFF

EXT APU BATT 2

200 A

GEN RH



DC–POWER

Fig. 38 DC Distribution Indications




TM-Electrical Power

INDEXAC Alternator System 8AC ELECTR. LOAD DISTRIBUTION 57AC External Power 47; 48AC Inverter System 8Alternator 1XA-1 (1XA-2) 12Alternator control unit 2XA (12XA) 13Battery 1PA, 11PA 41Battery System 25Bus Power Control Unit (BPCU) 20PC 30DC ELECTR. LOAD DISTRIBUTION 62DC Electrical Load Distribution System 53

DC external power 47; 52DC Relay Box (1VE) 37DC Starter/Generators 25Emergency DC Power System 25; 43Generator Control Unit 2PC (12PC) 30Ground Power Protection Unit 6XD 49Hall Effect Sensors 3PC (13PC), 4PC-1 (4PC-2) 30; 35Inverter 1XE, 2XE 21Inverter Circuit 23Starter/Generator 1PC-1 (1PC-2) 29 SieheTRU Circuit 46

LIST OF ILLUSTRATIONSFig. 1 Electric Panel................................................................................................................................................................................................5Fig. 2 Electric Bus System .....................................................................................................................................................................................6Fig. 3 AC Generation - Basic Configuration..........................................................................................................................................................7Fig. 4 Parts Location - Alternator System ..............................................................................................................................................................9Fig. 5 Alternator Function ....................................................................................................................................................................................12Fig. 6 Alternator Circuit .......................................................................................................................................................................................14Fig. 7 ALR Control Circuit ..................................................................................................................................................................................15Fig. 8 AC Relay Box 2VE....................................................................................................................................................................................17Fig. 9 AC System Indications ..............................................................................................................................................................................18Fig. 10 Parts Location - Inverter System..............................................................................................................................................................19Fig. 11 Inverter Circuit.........................................................................................................................................................................................22Fig. 12 Inverter System Indications......................................................................................................................................................................23Fig. 13 DC Generation - Basic Configuration......................................................................................................................................................24Fig. 14 Parts Location - Generator System ..........................................................................................................................................................26Fig. 15 Starter/Generator......................................................................................................................................................................................29Fig. 16 Starter/Generator System.........................................................................................................................................................................32Fig. 17 DC Power Monitoring System.................................................................................................................................................................34Fig. 18 Hall Effect Current Sensor .......................................................................................................................................................................35Fig. 19 HECS Schematic......................................................................................................................................................................................35Fig. 20 DC - Relay Box 1VE ...............................................................................................................................................................................37Fig. 21 Generator System Indications ..................................................................................................................................................................38Fig. 22 Parts Location - Battery System ..............................................................................................................................................................39Fig. 23 Battery System Indications ......................................................................................................................................................................42Fig. 24 Parts Location - TRU System..................................................................................................................................................................43Fig. 25 TRU Circuit..............................................................................................................................................................................................45Fig. 26 Parts Location - AC External ...................................................................................................................................................................48Fig. 27 External AC Circuit Diagram ..................................................................................................................................................................50Fig. 28 External AC Indications...........................................................................................................................................................................51Fig. 29 Parts Location - External DC System ......................................................................................................................................................52Fig. 30 External DC Circuit Diagram ..................................................................................................................................................................55Fig. 31 External DC System Indications.............................................................................................................................................................56Fig. 32 Parts Location - AC Distribution .............................................................................................................................................................57Fig. 33 AC Distribution ........................................................................................................................................................................................59Fig. 34 AC Distribution Indications.....................................................................................................................................................................60Fig. 35 Inverter Distribution Indications..............................................................................................................................................................60Fig. 36 Parts Location - DC Distribution .............................................................................................................................................................61Fig. 37 DC Distribution ........................................................................................................................................................................................65Fig. 38 DC Distribution Indications.....................................................................................................................................................................68

Dornier

End of ATA Chapter 24

Electrical Power

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