AC AUXILIARY GENERATION - Repair Maintenance and Operation

AC AUXILIARY GENERATION D/O (3)

APU GENERATOR

The APU generator can supply all or part of the normal network, depending on the priority logic provided by the bus tie logic. The APU generator is a two-pole high speed (24 000 rpm) brushless spray oil cooled generator. Speed regulation is made by the APU engine without a Constant Speed Drive (CSD); therefore, it operates in the same way but it is not interchangeable with the Integrated Drive Generators (IDGs).The APU generator is cooled and lubricated by the APU oil.

An oil temperature bulb is installed on the APU generator oil outlet part. The bulb is directly connected to the APU Electronic Control Box (ECB). In case of oil temperature above 185°C, the ECB commands an immediate shutdown of the APU.

APU GEN CONTROL MODULE (GAPCU)

The APU Generator Control Module is part of the Ground and Auxiliary Power Control Unit (GAPCU). The GAPCU controls both the APU generator and the EXT PWR.

The power supply for the GAPCU is provided by:

- the APU Permanent Magnet Generator (PMG),

- the EXT PWR,

- the BATtery BUS supply as a back-up supply.

The control module main functions are:

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

- voltage regulation,

- control of the APU Generator Line Contactor (GLC) through the Power Ready Relay (PRR) in conjunction with the bus tie logic,

- control and protection of the APU generator and the network.

The GAPCU has an interface with the SDAC and to the CFDIU.

APU ECB ensures the speed regulation. At 95% rpm, the ECB provides an APU ready signal to the GAPCU.APU GEN CONTROL AND MONITORING

The APU generator switch is used to connect or disconnect the APU generator and to reset the GAPCU.

- The FAULT legend only comes on if the switch is pressed in, the APU is running (>95%), and one parameter is not correct.

- The OFF legend comes on when the switch is released out.

After a fault detection (tripping of the generator), the GAPCU must be reset by setting the switch to OFF and back to ON.

The APU Generator Line Contactor (GLC) is under control of the GAPCU and the bus tie logic. If all generator parameters are correct, the AGLC connects the generator to the transfer line. The connection to the busbars depends on the priority logic and the network supply status (BTCs and GLCs).

TRANSFER CIRCUIT

The transfer circuit consists of the transfer line and the two BTCs. This circuit enables the power sources (GEN 1, 2, APU, External Power) to supply all or half of the network according to the priority and the bus tie logic.

The bus tie logic provides information about the network supply status. This information is used for:

- Non parallel operation,

- Supply priority,

- Transfer circuit control.

APU GEN FEEDER CABLES

The feeder cables are routed through the cabin ceiling to the rear C/B panel in the cockpit where they are sent through a 3-hole current transformer before connection to the APU GLC. The Current Transformer (CT) provides differential current protection.

OPERATION

The purpose of this paragraph is to describe the operation of the APU with or without GEN1.

ONLY APU RUNNING

With the APU MASTER and APU generator switches set to ON and APU running above 95%, the GCR is closed and the generator is excited. If all parameters are correct, the PRR is closed. With the APU GEN switch in ON position the APU GEN AUX relay 4XS is

energized. With the external power not connected (3XG and 5XG open = priority control) the power from the control module is sent via the bus tie logic to the solenoid of the APU GLC.

APU GENERATOR ... OPERATION

This Page Intentionally Left Blank

AC AUXILIARY GENERATION D/O (3) OPERATION (continued)

APU AND GEN1 RUNNING

If the APU GEN is supplying the entire electrical network and then Engine 1 is started, the bus tie logic changes as follows:

- GEN 1 has priority on AC BUS 1, so BTC 1 opens to allow GLC 1 to close. This prevents parallel operation between GEN 1 and the APU GEN.

- The APU GLC stays energized via the relaxed contacts of BTC 1 and GLC 2. The APU will continue supplying AC BUS 2.

OPERATION - APU AND GEN1 RUNNING

EXTERNAL POWER SUPPLY GENERAL DESCRIPTION (2) EXTERNAL POWER SUPPLY

The aircraft network can be supplied by a Ground Power Unit (GPU)

connected to the external power (EXT PWR) receptacle located forward

of the nose landing gear well.

EXTERNAL POWER SUPPLY

EXTERNAL POWER SUPPLY GENERAL DESCRIPTION (2) EXTERNAL POWER CONTROL

NORMAL PARAMETERS

If the external power parameters are correct, the indicator lights on

the external power panel and the A V AILable light on the EXT PWR

P/BSW come on. The power parameters are monitored by the Ground

and Auxiliary Power Control Unit (GAPCU) which activates the

indicator lights. With such indications the ground cart can supply the

aircraft network. When the EXT PWR P/BSW is pushed, the ON blue

legend illuminates and the GAPCU closes the External Power

Contactor (EPC) to supply the aircraft electrical network. The Bus

Tie Contactors (BTCs) 1 and 2 close if no engine driven generator is

on line.

The blue ON light, in the EXT PWR P/BSW, indicates that the EPC

is closed.

ABNORMAL PARAMETERS

If any external power parameter is not correct, the indicator lights

stay off. The external power cannot be connected to the aircraft

network.

EXTERNAL POWER CONTROL - NORMAL PARAMETERS & ABNORMAL PARAMETERS

EXTERNAL POWER SUPPLY D/O (3)

GENERAL

The Ground Power Unit (GPU) supplies the Transfer Circuit through the External Power Contactor (EPC).

A Ground and Auxiliary Power Control Unit (GAPCU) controls and protects the connection and disconnection of the GPU and the APU generator to the network.

GROUND POWER CONTROL & MONITORING

DESCRIPTION

The 115V AC, 400 Hz, 3 phase output of the GPU is connected to the aircraft network through the EPC and Bus Tie Contactors (BTCs).

The GAPCU monitors permanently the quality of the delivered ground power. The monitoring and control of the connection and

disconnection is made by two internal relays. The Interlock Monitoring Relay (IMR) and the Power Ready Relay (PRR). At least one faulty parameter opens both relays.

PRR AND IMR POWER SUPPLY

The IMR is energized when:

- The interlock voltage is more than 13V DC, less than 42V DC and less than 60V AC.

- All control and protection parameters are valid.

The PRR is energized when:

- The external power interlock is valid,

- And all parameters are correct.

The annunciators NOT IN USE and A V AILABLE located on the external power panel are ON.

SHORT CIRCUIT PROTECTION (PTC)

If a short circuit occurs on the PRR output line sensed by the Positive Temperature Coefficient (PTC) sensor, the red PTC TRIP LED on

the front face of the GAPCU comes on and a BITE message is sent to the Centralized Fault Display System (CFDS). OPERATION

EXT PWR NOT IN USE (A V AILABLE)

The closed PRR connects power from the internal supply via the PTC sensor to the distribution bus and from there:

- to the solenoid of EPC auxiliary relay. The auxiliary relay cannot be energized until it gets a ground signal from the flip/flop. The ground is supplied when the EXT PWR switch is pushed ON,

- to the EXT PWR NOT IN USE white light via the contactor 12XX provided that the MAINTenance BUS switch is off,

- directly to the EXT PWR A V AIL amber light.

GENERAL ... OPERATION

EXTERNAL POWER SUPPLY D/O (3) OPERATION (continued)

EXT PWR IN USE (ON)

When the External Power (EXT PWR) P/B switch is pressed

(momentary switch action), the flip flop provides a ground signal to the solenoid of the EPC auxiliary relay 5XG. The relay connects power from 1000XG to the GLC/BTC logic. Depending on the supply status the logic will authorize the closure of the EPC.

At the External Power panel:

- The NOT IN USE light will extinguish,

- The A V AIL light remains ON.

On the EXT PWR switch in the cockpit:

- The A V AIL light extinguishes,

- The ON light comes ON.

OPERATION - EXT PWR IN USE (ON)

GAPCU D/O (3)

GENERAL

The Ground and Auxiliary Power Control Unit (GAPCU) controls the APU Generator (GEN) and the External Power System. The APU Generator Line Contactor (GLC), the External Power Contactor (EPC) and their related Auxiliary Relays can only close when the correct conditions exist. They are opened manually or automatically, by the control and protection circuits.

The GAPCU also performs BITE analysis and communication, and interfaces with other systems:

- Generator Control Units (GCUs),

- APU Electronic Control Box (ECB),

- Centralized Fault Display Interface Unit (CFDIU),

- System Data Acquisition Concentrators (SDACs),

- Landing Gear Control and Interface Unit (LGCIU) 1.

POWER SUPPLY

The GAPCU internal power supply module can be supplied by the external power or the APU GEN via internal Transformer/Rectifiers (TRs). The supply module also has a back up supply from the BAT BUS.

EXT PWR CONTROL

The GAPCU performs the following functions for the external power control and BITE:

- monitoring,

- interlock function,

- External Power Contactor (EPC) control,

- protection,

- BITE function,

- communication and interface.MONITORING

The GAPCU permanently monitors the quality of the external power supply. A faulty parameter automatically disconnects the external power from the transfer line opening the Power Ready Relay (PRR) to open the EPC, and Interlock Monitoring Relay (IMR) to trip the ground cart. In some GAPCU failure conditions, the back-up card can control the PRR, so that the external power can still be connected to the aircraft. In these cases, after a "cold reset" the PRR closes and the external power is supplied to the aircraft with limited protection. In that case, no bite function is available.

EPC CONTROL

The closed PRR provides 28V DC to the solenoid of the EPC AUX relay (5XG). The AUX relay is responsible for opening and closing of the main contactor (EPC). The EPC AUX relay is also responsible for the priority switching, i.e. the External Power over the APU GEN. When the EXT PWR P/BSW is pressed the FLIP/FLOP provides a fixed ground signal to close the EPC AUX relay. Depending on the network supply status, the EPC AUX relay connects power via the de-energized APU GLC, to the EPC. The EPC then connects the GPU to the transfer line. When the EXT PWR P/BSW is pressed again, the FLIP/FLOP removes the ground so that the AUX relay and EPC open. PROTECTION

The GAPCU performs the following protection functions for the external power:

- over and under voltage,

- over and under frequency,

- over current,

- overload,

- EXT PWR interlock,

- Incorrect Phase Sequence (IPS),

- open cable or open/short circuit,

- EPC failure.

The Over V oltage (OV) protection is accomplished by monitoring the highest phase voltage at the Point Of Reference (POR). An OV condition exists when the highest phase voltage exceeds 130 +/- 1,5V AC. After an inverse delay, the IMR, PRR and EPC are tripped.

The Under V oltage (UV) is sensed in the same way as OV. An UV condition exists when the lowest phase voltage is less than 101,5 +/-1,5V AC. After a 4,5 second time delay max, the PRR, IMR and EPC are tripped.

An over current on the wiring between the PRR and the aircraft bus (1000XG) will change the status of the Positive Temperature

Coefficient (PTC) sensor (high impedance). The sensor then provides

a signal to switch on the red PTC LED on the front face of the GAPCU

and sends a BITE message to the Centralized Fault Display System (CFDS).

The PTC and the PTC LED are only supplied if the EXT PWR remains connected to the receptacle (i.e. PRR is still closed). The LED is not

a "latched" status signal. Thus, if a short circuit does exist, and the

LED is illuminated, it will go off as soon as the external power is removed from the receptacle.

APU GEN CONTROL

The main functions are:

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

- voltage regulation,

- control of the APU GLC through the PRR in conjunction with the BTC/GLC logic,

- control and protection of the APU GEN and the network.

APU P/BSW

The APU GEN P/BSW is used to connect or disconnect the APU GEN and to reset the APU GEN control part. After a fault detection

(tripping of the generator), the control and must be reset by setting the P/BSW to OFF and back to on.

APU GLC CONTROL AND MONITORING

The APU GLC is under control of the APU GLC AUX relay and the GLC/BTC logic. If all APU GEN parameters are correct, the APU GLC connects the APU GEN power to the transfer line.

OVERHEAT PROTECTION

An oil temperature bulb is installed on the APU GEN oil outlet port.

The bulb is directly connected to the APU ECB. In case of oil

temperature above 185°C, the ECB commands an immediate shutdown of the APU.

COMMUNICATION AND INTERFACE

The GAPCU is connected with the GCUs, the CFDIU and the SDACs.

WITH THE GCU

The GAPCU communicates with the two GCUs via MIL-STD 1553 links.

WITH THE CFDIU

The GAPCU is the CFDS interface for the enhanced Electrical Power Generation System (EPGS). The GAPCU communicates with the CFDIU via ARINC 429 links. During normal mode of transmission, the GAPCU continuously sends its own and the two GCUs fault data, to the CFDIU.

WITH THE SDAC

The GAPCU continuously communicates with the SDACs via ARINC 429 links. The SDACs provide system data and fault data to the

ECAM.

INTERFACE WITH LGCIU 1

The GAPCU receives a flight/ground discrete signal from LGCIU 1. It enables communication in interactive mode between the GCU and the GAPCU and the CFDIU, when the aircraft is on ground.

GENERAL ... COMMUNICATION AND INTERFACE

# AC/DC GROUND SERVICE DISTRIBUTION D/O (3) EXT PWR P/B ON

With the EXTernal PoWeR available and the EXT PWR P/B on, the

whole aircraft electrical network is supplied including the AC and DC GrouND/FLighT buses. The MAINTenance BUS switch (5XX) is off.

EXT PWR P/B ON

# AC/DC GROUND SERVICE DISTRIBUTION D/O (3) MAINT BUS SW ON

EXT PWR is available but not on (14PU and 12XN open) and the MAINT

BUS switch switched to ON. AC BUS 2 and 202XP are not energized,

so relay 7XX is de-energized and supplies relay 14XX via relay 14PU

and relay 12XX via relay 12XN. With these two relays energized, the

DC GND/FLT bus (6PP) is supplied via Transformer Rectifier (TR) 2

and the AC GND/FLT buses (212XP, 216XP and 214XP) via 12XX and

14XX.

本文来源：https://www.bwwdw.com/article/59sq.html