Ground and Auxiliary Power Control Unit _ Description and op

Ground and Auxiliary Power Control Unit _ Description and operation

GAPCU D/O (3)

GENERAL

The Ground and Auxiliary Power Control Unit (GAPCU) controls theAPU 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 thecontrol and protection circuits.

The GAPCU also performs BITE analysis and communication, andinterfaces 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 theexternal 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 powercontrol and BITE:

- monitoring,

- interlock function,

- External Power Contactor (EPC) control,

- protection,

- BITE function,

- communication and interface.MONITORINGThe GAPCU permanently monitors the quality of the external powersupply. A faulty parameter automatically disconnects the externalpower from the transfer line opening the Power Ready Relay (PRR)to open the EPC, and Interlock Monitoring Relay (IMR) to trip theground cart. In some GAPCU failure conditions, the back-up card cancontrol the PRR, so that the external power can still be connected tothe aircraft. In these cases, after a "cold reset" the PRR closes and theexternal power is supplied to the aircraft with limited protection. Inthat case, no bite function is available.EPC CONTROLThe closed PRR provides 28V DC to the solenoid of the EPC AUXrelay (5XG). The AUX relay is responsible for opening and closingof the main contactor (EPC). The EPC AUX relay is also responsiblefor the priority switching, i.e. the External Power over the APU GEN.When the EXT PWR P/BSW is pressed the FLIP/FLOP provides afixed ground signal to close the EPC AUX relay. Depending on thenetwork supply status, the EPC AUX relay connects power via thede-energized APU GLC, to the EPC. The EPC then connects the GPUto the transfer line. When the EXT PWR P/BSW is pressed again, theFLIP/FLOP removes the ground so that the AUX relay and EPC open.PROTECTIONThe GAPCU performs the following protection functions for theexternal 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,

Ground and Auxiliary Power Control Unit _ Description and operation

- EPC failure.

The Over Voltage (OV) protection is accomplished by monitoring

the highest phase voltage at the Point Of Reference (POR). An OVcondition exists when the highest phase voltage exceeds 130 +/- 1,5VAC. After an inverse delay, the IMR, PRR and EPC are tripped.

The Under Voltage (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 EPCare 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 providesa signal to switch on the red PTC LED on the front face of the GAPCUand sends a BITE message to the Centralized Fault Display System(CFDS).

The PTC and the PTC LED are only supplied if the EXT PWR remainsconnected to the receptacle (i.e. PRR is still closed). The LED is nota "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 theBTC/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 settingthe P/BSW to OFF and back to on.APU GLC CONTROL AND MONITORINGThe APU GLC is under control of the APU GLC AUX relay and theGLC/BTC logic. If all APU GEN parameters are correct, the APUGLC connects the APU GEN power to the transfer line.OVERHEAT PROTECTIONAn oil temperature bulb is installed on the APU GEN oil outlet port.The bulb is directly connected to the APU ECB. In case of oiltemperature above 185°C, the ECB commands an immediate shutdownof the http://www.77cn.com.cnMUNICATION AND INTERFACEThe GAPCU is connected with the GCUs, the CFDIU and the SDACs.WITH THE GCUThe GAPCU communicates with the two GCUs via MIL-STD 1553links.WITH THE CFDIUThe GAPCU is the CFDS interface for the enhanced Electrical PowerGeneration System (EPGS). The GAPCU communicates with theCFDIU 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 SDACThe GAPCU continuously communicates with the SDACs via ARINC429 links. The SDACs provide system data and fault data to theECAM.

Ground and Auxiliary Power Control Unit _ Description and operation

INTERFACE WITH LGCIU 1

The GAPCU receives a flight/ground discrete signal from LGCIU 1.It enables communication in interactive mode between the GCU andthe GAPCU and the CFDIU, when the aircraft is on ground …… 此处隐藏：7338字，全部文档内容请下载后查看。喜欢就下载吧 ……