B767 200-300 BOOK 24 101 - Electrical Power

B767/24/101 Electrical Power

Boeing 767-200/300

Electrical Power Training manual For training purposes only LEVEL 1

ATA 24

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This publication was created by Sabena technics training department, Brussels-Belgium, following ATA 104 specifications. The information in this publication is furnished for informational and training use only, and is subject to change without notice. Sabena technics training assumes no responsibility for any errors or inaccuracies that may appear in this publication. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Sabena technics training.

Contact address for course registrations course schedule information Sabena technics training [email protected]

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LIST OF EFFECTIVE PAGES 1................................................ 13 - 04 - 2012 2................................................ 13 - 04 - 2012 3................................................ 13 - 04 - 2012 4................................................ 13 - 04 - 2012 5................................................ 13 - 04 - 2012 6................................................ 13 - 04 - 2012 7................................................ 13 - 04 - 2012 8................................................ 13 - 04 - 2012 9................................................ 13 - 04 - 2012 10.............................................. 13 - 04 - 2012 11.............................................. 13 - 04 - 2012 12.............................................. 13 - 04 - 2012 13.............................................. 13 - 04 - 2012 14.............................................. 13 - 04 - 2012 15.............................................. 13 - 04 - 2012 16.............................................. 13 - 04 - 2012 17.............................................. 13 - 04 - 2012 18.............................................. 13 - 04 - 2012 19.............................................. 13 - 04 - 2012 20.............................................. 13 - 04 - 2012 21.............................................. 13 - 04 - 2012 22.............................................. 13 - 04 - 2012 23.............................................. 13 - 04 - 2012 24.............................................. 13 - 04 - 2012 25.............................................. 13 - 04 - 2012 26.............................................. 13 - 04 - 2012 27.............................................. 13 - 04 - 2012 28.............................................. 13 - 04 - 2012 29.............................................. 13 - 04 - 2012 30.............................................. 13 - 04 - 2012 31.............................................. 13 - 04 - 2012 32.............................................. 13 - 04 - 2012 33.............................................. 13 - 04 - 2012 34.............................................. 13 - 04 - 2012

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TABLE OF CONTENTS 1. ELECTRICAL SYSTEM SUMMARY. .......................................................... 6 1.1. External Power. ...................................................................................... 6 1.2. Integrated Drive Generator System....................................................... 10 1.3. IDG Cooling and Control. .................................................................... 12 1.3.1. GE CF6. ....................................................................................... 12 1.3.2. PW 4000. .................................................................................... 14 1.4. IDG Temperature Monitoring. .............................................................. 16 1.4.1. GE CF6. ....................................................................................... 16 1.4.2. PW4000. ..................................................................................... 16 1.5. DC Power System. ............................................................................... 18 1.6. System Control and Indication. ............................................................ 18 1.7. AC Power System. ............................................................................... 20 2. ELECTRICAL SYSTEM PANELS. ............................................................. 22 2.1. Electrical System Control Panel (P5). ..................................................... 22 2.2. Auxiliary Electrical System Control Panel............................................... 24 2.3. Ground Service/Misc Test Panel. ........................................................... 26


LIST OF ILLUSTRATIONS AC POWER INDICATION......................................................................................................... 34 APU GENERATOR EXTERNAL DETAILS .................................................................................... 31 AUXILIARY ELECTRICAL CONTROL PANEL .............................................................................. 25 DC POWER INDICATION......................................................................................................... 18 ELECTRICAL SYSTEM ............................................................................................................. 21 ELECTRICAL SYSTEM CONTROL PANEL .................................................................................. 23 EXTERNAL POWER PANEL ...................................................................................................... 29 GROUND SERVICE / MISC. TEST PANEL .................................................................................. 27 HYDRAULIC MOTOR GENERATOR SYSTEM ............................................................................ 33 IDG AIR / OIL COOLING.......................................................................................................... 15 IDG FUEL / OIL EXCHANGER .................................................................................................. 13 INTEGRATED DRIVE GENERATOR SYSTEM .............................................................................. 11 MAIN AND APU BATTERY CHARGING SYSTEM ...................................................................... 19 POWER DISTRIBUTION ............................................................................................................. 7 POWER DISTRIBUTION - GENERAL............................................................................................ 9 TRANSFORMER RECTIFIER UNIT.............................................................................................. 19

3. AC EXTERNAL POWER SYSTEM. .......................................................... 28 3.1. System Description............................................................................... 28 4. APU GENERATOR.................................................................................. 30 4.1. Physical Description.............................................................................. 30 5. HYDRAULIC MOTOR GENERATOR SYSTEM. ....................................... 32 5.1. System Description............................................................................... 32 5.2. AC Power Indications. .......................................................................... 34

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ABBREVIATIONS AND ACRONYMS ACMP ADF AFT Agcu Agb ALT AOA APB APU BAT BITE BPCU BTB CB CHGR CMD COMM CONT CSD CT CTA CTR DCTCU DME DPCT EADI EAROM EEC EFIS EHSI EICAS ELCU ELEC EMI EQUIP COOL EP EPC EPREQ EXT FCC

Alternating Current Motor Pump Automatic Direction Finder Afterwards Apu Generator Control Unit Accessory Gearbox Altitude Angle Of Attack APU Breaker Auxiliary Power Unit Battery Built In Test Equipment Bus Power Control Unit Bus Tie Breaker Circuit Breaker Charger Command Communication Control(ler) Constant Speed Drive Current Transformer Current Transformer Assembly Center DC Tie Control Bus Distance Measurement Equipment Differntial Protection Current Transformer Electronic Attitude Direction Indicator Electrically Alterable Read Only Memory Electronic Engine Control Electronic Flight Instrument System Electronic Horizontal Situation Indicator Engine Indicating and Crew Alerting System Electrical Load Control Unit Electric(ally) Electromagnetic Interference Equipment Cooling External Power External Power Contactor External Power Request External Flight Coltrol Computer

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FLT FMCS FWD GCB GCR GCU GEN GHB GHR GND GSB GSSR GSTR HF HMG HYD IAS IDG ILS IND INTLK INTPH IRU ISLN LAV Lct LRU LTS MAN MPU Nct NVM OF OV OVHD Pdp PDT PMG PNL POR

Flight Flight Management Computer system Forward Generator Control Breaker Generator Control Relay Generator Control Unit Generator Ground Handling Bus Ground Handling Relay Ground Ground Service Bus Ground Service Select Relay Ground Service Transfer Relay High Frequency Hydraulic Motor generator Hydraulic(ally) Indicated Airspeed Integrated Drive Generator Instrument Landing System Indicator Interlock Interphone Inertial Reference Unit Isolation Lavatory Line Current Transformer Line Replaceable Unit Lights Manual Magnetic Pick Up Neutral Current Transformer Non-Volatile Memory Over Frequency Over Voltage Overhead Power Distribution Panel Pole Double Throw Permanent Magnet Generator Panel Point Of Regulation

PST PWR QAD RCCB RDMI REF SENS STBY TEMP TR TRU UBR UF UTIL UV VHF VOR Vr VSI XFER XFMR

Pole Single Throw Power Quick Attach Detach Remote Control Circuit Breaker Radio Distance Magnetic Indicator Reference Sensor Standby Temperature Transformer Rectifier Transformer Rectifier Unit Utility Bus Relay Under Frequency Utility Under Voltage Very High Frequency VHF Omnidirectional Range Voltage Regulator Vertical Speed Indicator Transfer Transformer

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1. ELECTRICAL SYSTEM SUMMARY. 1.1. External Power. The external power system allows 115 volt ac ground power to be connected for powering the ground handling, ground service, and left and right main ac buses. An external power source is connected to the external power receptacle located in the P30 panel. Other external power components are located in the main equipment center P34, P33 panels and E2 rack. If the Bus Power Control Unit (BPCU) senses good power quality the AC CONNECTED and PWR NOT IN USE LIGHTS (P30) and AVAIL LIGHT (P5) are illuminated. The BPCU initiates opening and closing of the external power contactor, ground handling relay, and ground service select and transfer relays. It provides external power monitoring for fault isolation and contains BITE for the complete electrical system. The ground handling bus is automatically powered for good external power quality, and external power is given priority over APU generator power. The ground service bus receives power automatically when the right main AC bus is powered. When the right main bus is not powered, pushing the GROUND SERVICE switch (P21 forward attendants panel) allows the ground service bus to be powered either from external power or APU generator. Pushing the EXT PWR switch (P5 overhead panel) closes the external power contactor and the EXT PWR ON light illuminates. External power has priority over the integrated drive generator (IDG) and APU generator when manually selected. After both generator circuit breakers close, the external power contactor is tripped open. The BPCU protection circuitry monitors external power current, voltage and frequency for fault isolation tripping of the external power contactor, ground handling relay and ground service select and transfer relays. External power contactor fault protection trips are reset by pushing the EXT PWR switch. Ground handling and ground service system fault protection trips are reset by pushing the GROUND SERVICE switch.

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Power Distribution. Each power feeder includes a length of high temperature copper wire and a length of light weight aluminium wire spliced together. Copalum splices are used to connect the copper and aluminium wires together. The IDG power feeder splices are located in the upper part of the nacelle strut. The APU generator power feeder splices are located between the APU firewall and the rear pressure bulkhead. The all copper external power feeder is one piece. The IDG power feeders can only be disconnected at the IDG terminal block. For the APU generator, power feeders are disconnected at either the firewall or the generator terminal block. The tie bus feeders interconnect the main power panel distribution centers through the bus tie breakers. Connections are provided to the auxiliary power breaker and the external power contactor. Tie bus feeders between BTB’s, APB and EPC are connected in a ring-bus configuration.

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R

ELCU

T

L - AC BUS

UTIL BUS RLY.

LIDG

EXTERNAL POWER

LGCB

L - XFR. BUS RLY.

BPCU

GCU L

LBTB

ALT.

INST. BUS VOLT SENS.

DC TIE RLY

HYD. GEN. DC PWR. RLY.

APU GEN

APB

ALT.

INST. BUS VOLT SENS.

APU GCU

GCU R

RBTB

NORM.

RIDG

UTIL BUS RLY.

28V AC BUS

28V AC BUS RGCB

T

ELCU R - AC BUS

ISLN

W

AUTO

BUS TIE

O F ON F W

L GEN CONT

BUS OFF

L BUS

R. - 28V DC BUS

G A L L E Y

W

OFF

AUTO

W

R

OFF

ON

W

DRIVE

W

W

DRIVE

GEN DRIVE DISC L R

OFF

ON

L

UTIL BUS

W

O ON W F ON F AVAIL W

O F F

W

O F ON F W

R GEN CONT

BUS OFF

R BUS

ISLN

AUTO

BUS TIE

BAT

STBY POWER

APU GEN EXT PWR

MAIN BAT APU BAT DISCH DISCH

OFF

ON

BAT


T R

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GND. HND. RLY.

AC GND. HND. BUS

28V AC GND. SVC. BUS

LOAD SHED. RLY.

GND. SVC. SELECT. RLY.

AC GND. SVC. BUS

GND. SVC. XFR. RLY.

R

DC GND. HND. BUS

APU BATT. CHGR. RLY.

GND. SVC. EXT. BUS

MAIN BATT. CHGR. RLY.

TO MAIN BATT. CHGR.

APU BATT CHGR

APU BATT. BUS

POWER DISTRIBUTION PANEL (ON P5)

APU CRANCK CTCTR

R - UTIL BUS

R - XFR. BUS

HMG

R - XFR. BUS RLY.

AC

DC

TO MAIN APU BAT. TIE RCCB

TO APU STARTER MOTOR

POWER DISTRIBUTION

EPC

NORM.

INST. XFR. BUS RLY.

CAPT FLT INST. XFR. BUS

C - BUS XFR. RLY.

C - 115V AC BUS

F/O FLT INST. XFR. BUS

L - XFR. BUS

INV.

STAT

AC STBY. PWR. RLY.

AC STBY BUS

C. - 28V DC BUS C - BUS XFR. RLY.

STBY. PWR. RLY.

L - UTIL BUS

28V AC BUS

G A L L E Y

28V AC BUS

L. - 28V DC BUS

FROM APU MAIN APU BAT. BAT. TIE RCCB

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FROM AC GND. SERV. BUS

MAIN BATT CHGR

HOT BATT. BUS

MAIN BATT. RLY.

MAIN BATT. XFR. RLY.

BATT BUS

DC STBY BUS

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T S H C I G I N R H Y C P E O T C A U N R E B B A S

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1.2. Integrated Drive Generator System. The generator outputs 115/200 volt, 3-phase, 400 Hz, ac power and is rated at 90 KVA. Each integrated drive generator is QAD ring attached to the accessory gearbox. Constant generator speed is maintained by a mechanical speed governor. The disconnect reset ring allows reconnection of the IDG input spline mechanical connection after a disconnect. Two electrical connectors provide IDG to GCU interface for control, protection and monitoring. A terminal block is used for power feeder connections. The IDG is cooled by an external oil cooling system composed of fuel/oil and air/oil heat exchanger assemblies connected in series. The fuel/oil heat exchangers use engine fuel to cool IDG oil. An air/oil heat exchanger receives fan air through a pneumatic and electrically controlled cooling air shutoff valve. A generator drive disconnect switch, when pushed, disconnects the IDG input shaft from the engine accessory gearbox if the associated engine fuel control switch is not in cutoff.

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INTEGRATED DRIVE GENERATOR SYSTEM EFFECTIVITY ALL

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1.3. IDG Cooling and Control. 1.3.1. GE CF6. IDG Fuel/Oil Heat Exchanger. This unit provides primary cooling for the integrated drive generator oil during normal flight operations. Location. The heat exchanger is attached to the accessory gearbox lower right side. IDG Air/Oil Heat Exchanger. The air/oil heat exchanger cools IDG oil when the fuel/oil heat exchanger has insufficient fuel flow. A cooling air shutoff valve controls fan air flow to the air/oil heat exchanger. Location. The air oil heat exchanger and cooling air shutoff valve are on the engine compressor case at approximately 4 o’clock. The air/oil heat exchanger is a tube and fin-type heat exchanger. Heated oil flows from the inlet port through tubes to the outlet port. An air supply duct on the engine fan case directs fan air through the cooling air shutoff valve. The fan air passes over the heat exchanger fins.

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IDG FUEL / OIL EXCHANGER EFFECTIVITY ALL

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1.3.2. PW 4000. Purpose. The IDG Air/Oil Heat Exchanger cools the IDG oil when the Fuel/Oil Cooler has insufficient capability. Airflow through the heat exchanger is controlled by the IDG Air/Oil Heat Exchanger Valve. The HPC Secondary Flow Control/IDG Air Oil Heat Exchanger Valve Override Solenoid controls Ps3 pneumatic pressure to the Override Fuel Pressure Switch. Location. The IDG Air/Oil Heat Exchanger and Valve are mounted in the aft side of the intermediate case at the 4 o’clock position. The HPC Secondary Flow Control/IDG Air/Oil Heat Exchanger Valve Override Solenoid and the Override Fuel Pressure Switch are mounted on the aft side of the intermediate case at the 1 o’clock position.

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1.4. IDG Temperature Monitoring. 1.4.1. GE CF6. IDG temperature is monitored by two temperature sensors located inside the IDG. After processing the GCU sends IDG rise and oil out temperature to EICAS for display on the ELEC/HYD page. Operation. EICAS supplies a dc reference voltage to the GCU’s trough resistor R10111. The voltage and current of this ref circuit vary with IDG temperature (1 mA = 180 °C). This changing voltage represents the IDG temp and is monitored by the EICAS computers. The K1 timer module located in the P61 panel signals the GCU to transmit either oil out or rise temp. The same signal is used to inform EICAS which temperature is being transmitted by the GCU. If the K1 timer should fail in the ground (rise temp) or open position (outlet temp) for longer than 5 seconds EICAS will blank the failed temperature indication for both IDG’s. Indication. IDG oil out and rise temp are displayed on the ELEC/HYD page. The GCU alternately transmits oil out and oil rise temperature sensor in one of the following ways : - Both temp sensors failed. Transmit 180 °C for oil out and rise temp. - Oil in or oil out temp sensor failed. Set rise temp to 8 °C if engine is running or 0 °C if engine is not running. - Oil out temp sensor failed. Oil out indication will be oil in + 8 °C with engine running and oil in temp with engine not running. - Oil in temp sense failed. The GCU uses oil out - 8 °C for oil in.

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1.4.2. PW4000. Operation. The generator control unit monitors the IDG inlet and outlet oil temperature sensors located in the IDG. The sensors are temperature bulbs whose resistance varies with oil temperature. Each sensor is read by the microprocessor through an analog-to-digital converter. The signals are converted to temperature units in °C. The generator control unit provides IDG oil temperature signals to both EICAS computers for display on the EICAS ELEC/HYD maintenance page. A dc reference voltage is supplied by each EICAS computer. The generator control unit controls the current flow based on IDG outlet and rise temperature. Current flow varies up to a maximum of 1 ma. A voltage divider is used to send a voltage to each EICAS computer. This voltage is compared with the dc reference voltage to compute either IDG OUT or IDG RISE temperature. The data is displayed from 0 to 180 °C. The K1 TIMER module located in the P61 panel change’s the information requested every 0.5 second (from open - to closed then back to open) . The closed circuit discrete represents a request for IDG RISE temperature and the open condition a request for IDG OUT temperature. Real time updating occurs 200 msec after the IDG OUT temperature discrete is sensed. Each outlet temperature pulse normally resets and starts a 5 second counter. If the discrete ceases for greater than 5 seconds, the, opposite value of IDG OUT temperature or IDG RISE temperature for both IDG’s goes blank. The remaining displayed value is continuously updated.

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1.5. DC Power System. The dc power system supplies loads requiring dc power. Both transformer rectifier units (TRU) are located in the main equipment center. The main battery, battery charger and static inverter are located in the main equipment center. An APU battery and battery charger are located in the aft equipment center. The main battery/battery charger system provides dc power for the standby and autoland systems. A separate APU battery/battery charger system supplies power for APU starting. Both batteries are 40 amp-hour, 20 cell nickel-cadmium, rated at 24 volt dc. In the charge mode, battery charging is constant current and temperature compensated. A thermistor and thermal switch, both integral to the battery, provide temperature sensing and overtemperature protection signals for charger control and shut-down. In the transformer rectifier unit mode, the battery charger supplies constant voltage. The standby system static inverter supplies single phase AC power for the ac standby bus. The BAT switch controls back-up dc input inverter power and the STBY POWER rotary switch controls auto/manual standby modes. Each TRU normally supplies its own dc load buses. An automatic operating dc tie control unit allows a single TRU to supply both main dc buses. A remote control circuit breaker (RCCB) automatically closes during standby power system operation tying the main and APU battery buses together.

1.6. System Control and Indication. Manual or automatic source selection is provided during ground and inflight operations from the electrical system and auxiliary electrical system control panels located in the flight compartment. Electrical system monitoring is displayed on EICAS.

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TRANSFORMER RECTIFIER UNIT EFFECTIVITY ALL


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1.7. AC Power System. During normal operations, the ac system uses the electrical output of the two IDG’s, with each IDG powering its associated channel. For ground operations, external power or the APU generator can power either or both channels. The APU generator can also be used in flight as a back-up source, should an IDG fail. The APU generator, mounted to the APU gearbox, is cooled and lubricated using APU oil. The electrical output of the APU generator is the same as that of an IDG. Each GCU (El and E2 racks) automatically controls and protects an individual generating channel by monitoring source output from IDG or APU generator, serial data link to and from the BPCU and control switch positions. Main power breakers (P31, P32 and P34) control ac power flow and are all (except EPC) interchangeable.


The hydraulic motor generator (HMG) system provides a back-up source of electrical power after loss of all generators. An air-driven hydraulic pump pressurizes the center hydraulic system to power the HMG. The HMG and shutoff valve are located in the left wheel well. A generator control unit (P65) performs control and protection functions. A momentary test switch (P61) is used to perform system check-out. Ac bus transfer relays connect the captain’s, left and right ac transfer buses to the hydraulic motor generator AC output. A DC contactor connects the hydraulic motor generator dc output to the hot battery bus.

Current transformer assemblies monitor current flow for open phase, differential protection, load monitoring and overload protection. Electrical load control units and utility bus relays (P31 and P32) connect nonessential galley and utility bus loads to main ac buses. A GEN CONT switch controls the associated field relay (GCR) and main power breaker (GCB or APB). Latching the switch (ON) closes the GCR. Unlatching the switch (OFF) opens the GCR. If the GEN CONT switch is unlatched, then the GCR is opened and closed using GEN FIELD switch. With the GEN CONT switch latched the main power breaker is automatically opened and closed by the associated GCU. The BTB is automatically controlled by the associated GCU if the corresponding BUS TIE switch is latched (AUTO). The GCU and BPCU protective functions monitor system current, voltage, frequency and input speed for open phase, overvoltage, undervoltage, shorted permanent magnet generator, underfrequency, overfrequency, shorted rotating diode, underspeed, differential current and load shedding faults.

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ELECTRICAL SYSTEM EFFECTIVITY ALL

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2. ELECTRICAL SYSTEM PANELS. Normal operation of the electrical power system is performed at the electrical system control panel and the auxiliary electrical system control panel. Both momentary and alternate action pushbutton switches are used on the electrical panels. The alternate action switches are normally in the latched (ON) position. This allows automatic operation of the electrical system breakers and relays under the control of the system’s computers. Switch indicator lights are powered by the master dim and test system.

2.1. Electrical System Control Panel (P5). The momentary external power switch controls the position of the external power contactor. A white AVAIL light indicates power is of proper quality. The white ON light illuminates when the external power contactor is closed. The generator control switches provide a control signal which closes the generator control relay (GCR), and, when proper power is available, enables automatic closing of the generator circuit breaker (GCB). The flow bar and ON legend indicate switch position. An amber OFF light illuminates when the associated generator circuit breaker is open. The ac bus tie switches allow manual or automatic control of the bus tie breaker (BTB). When a switch is unlatched, the associated BTB is locked open, isolating the associated main ac bus from the ac tie bus. In this case, the AUTO indication is not visible and the amber ISLN light is illuminated. Latching an ac bus tie switch (ON) enables automatic operation of the associated bus tie breaker. In this case, the AUTO light normally illuminates and the ISLN light is off. If the ISLN light illuminates when the bus tie switch is latched, then a fault has tripped and locked the BTB open.

The alternate action utility bus switches provide manual control of the power relays connecting utility and galley buses to the main ac buses. The ON legend is seen when the switch is latched (ON). The amber OFF light illuminates when the associated utility bus relay (UBR) is open. Pushing the momentary generator drive disconnect switches causes a mechanical disconnection between the integrated drive generator and the engine when the associated engine fuel control switch is not off. An amber DRIVE light on the switch illuminates for a mechanical failure of the IDG or when the engine is not running. The alternate action battery switch controls connection of the battery bus to the left dc bus or the hot battery bus. The ON legend is seen when the switch is latched (ON). An amber OFF light illuminates when the battery switch is unlatched during normal ground and flight operations. For the main and APU batteries, a dedicated battery discharge light illuminates if the battery is discharging. The standby power mode of operation is controlled by the standby power selector switch. To turn the switch off, push the switch in, when going from the AUTO to the OFF position. An amber standby power bus OFF light illuminates when the ac or dc standby bus is unpowered.

An ac BUS OFF indicator light illuminates when the associated main ac bus is de-energized.

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ELECTRICAL SYSTEM CONTROL PANEL EFFECTIVITY ALL

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2.2. Auxiliary Electrical System Control Panel. The momentary generator field manual reset switch is pushed to open and close the generator field control relay when the generator control switch is unlatched. A white FIELD OFF light illuminates when the generator control relay (GCR) is open.

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AUXILIARY ELECTRICAL CONTROL PANEL EFFECTIVITY ALL

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2.3. Ground Service/Misc Test Panel. Ground Service Switch. A single momentary switch allows the ground service bus to be powered directly from the APU generator or external power. Pushing the ground service switch connects or disconnects the APU generator or external power if the right main ac bus is de-energized. A light inside the switch illuminates to indicate that the ground service bus is powered directly from external or APU generator power. Hydraulic Motor Generator Test Switch. A momentary toggle switch (EQUIP COOL/HYD GEN) on the right side P61 panel is provided for hydraulic motor generator system testing. When toggled to the HYD GEN position, the test switch simulates loss of both main ac buses, and provides a start-up signal to the hydraulic motor generator system. Release of the test switch causes system shut-down and transfer of loads back to normal bus sources.

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GROUND SERVICE / MISC. TEST PANEL EFFECTIVITY ALL

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3. AC EXTERNAL POWER SYSTEM. 3.1. System Description. A ground power source can be connected at the airplane external power receptacle to supply power to the 767 ac electrical power system. Power is supplied to main load buses when the external power contactor (EPC) and corresponding bus tie breakers (BTB’s) close. The external power source also supplies power to the ground service and ground handling buses, using the ground service select, ground service transfer, and ground handling relays. Component Locations. An external power receptacle (P30 panel) is located on the lower fuselage, just aft of the nose gear. All other external power system components are located in the main equipment center. There are two control switches. An EXT PWR switch is located on the P5 overhead panel, and a ground service switch is located on the P21 forward attendant’s panel.

The 115 volt ac ground handling bus is automatically powered on the ground if external power is of acceptable quality. The BPCU controls the three position ground handling relay and automatically gives external power priority over the APU generator. Ground service bus power is supplied to equipment which must be powered in both air and ground modes. This bus receives power automatically from the right main ac bus if that bus is powered. If the right main bus is not powered, pressing the ground service switch allows supply of either external power or APU generator power (whichever is first available) to the ground service bus. If both external and APU generator power are available when the ground service switch is pressed, external power is used. If a fault exists in the external power circuit, BPCU trips the EPC to protect the power source and loads.

Operation. The Bus Power Control Unit (BPCU) controls the EPC. The EPC controls the flow of external power to the ac tie bus. When external power of acceptable quality (as determined by the BPCU) is first connected, the AC CONNECTED and PWR NOT IN USE lights on the P30 panel come on. Also, the AVAIL light on the EXT PWR switch comes on. Pressing the momentary EXT PWR switch closes the EPC. When the EPC closes, the ON light on the EXT PWR switch comes on. External power always has priority over the IDG’s and APU generator when manually selected. If both engines are started and the IDG’s are ready to supply electrical power, then, automatically, the EPC and BTB’s are tripped open and the GCB’s close. If both engines are operating, and external power is supplying power to the main buses, cycling the generator control switches (unlatch-latch) also causes the EPC and BTB’s to trip open and the GCB’s to close. EFFECTIVITY ALL

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EXTERNAL POWER PANEL EFFECTIVITY ALL

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4. APU GENERATOR. 4.1. Physical Description. The electromagnetic components of the auxiliary generator are the same as those used in the IDG and are interchangeable except that the APU generator is contained in its own magnesium cast housing and has a different input spline and mounting flange. The generator weighs 61.9 pounds (27.63 kg) dry weight. Keyhole slots allow mounting of the generator to the auxiliary power unit accessory gearbox. An aluminium seal plate is installed between the generator mounting flange and gearbox drive pad. The mounting flange incorporates three locating pins to position the generator on the APU flange. Elastomer compound inserts are installed in the seal plate “OIL-IN” and “OILOUT” ports. The input shaft incorporates a shear section that shears at 4700 ± 300 in-lbs. The APU generator is spray oil cooled and lubricated using APU engine oil. Pressurization, scavenging and filtering of the oil is provided by the auxiliary power unit. Generator case pressure, 5 psig above ambient, is introduced from the APU gearbox through a rotating screw passageway in the input shaft. APU generator oil is filtered by a 20/40 micron filter. The delta pressure (popout) indicator activates at 20 psid. A mechanical lockout prevents activation when oil temperature is below 115 °F (46 °C). When the filter delta pressure reaches 35 psid and oil temperature above 115 °F (46 °C) an APU shut-down is initiated by the DP switch. A terminal block with four stainless steel studs provides the feeder connections. A single electrical connector provides all other electrical connections.

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APU GENERATOR EXTERNAL DETAILS EFFECTIVITY ALL

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Training manual


5. HYDRAULIC MOTOR GENERATOR SYSTEM. The hydraulic motor generator system provides a non-time limited back-up source after loss of all generator electrical power.

5.1. System Description. The hydraulic motor generator (HMG) is located in the left wheel well. The generator is driven by a hydraulic motor supplied from the center hydraulic system. An air-driven hydraulic pump (ADP), supplied by left or right engine bleed air, can pressurize the center hydraulic system. A motor driven hydraulic shutoff valve provides on/off control for the HMG. Automatic activation of the hydraulic motor generator system occurs with loss of power to both main ac buses. A flow limiter regulates hydraulic flow to the trailing edge flaps and leading edge slats during HMG operation. Control and protection functions are performed by the generator control unit located in the P65 panel. A momentary test switch (P61 panel) is provided for system check-out. The HMG system operational status and electrical parameters are monitored by EICAS.

EFFECTIVITY ALL

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Training manual


HYDRAULIC MOTOR GENERATOR SYSTEM EFFECTIVITY ALL

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Training manual

5.2. AC Power Indications. Generator Load. Each GCU provides a dc voltage output to both EICAS computers proportional to the associated ac generator channel load. The GCU senses generator load current from the generator current transformers. Generator load is displayed on the EICAS ELEC/HYD maintenance page for values between 0/0.05 to 1.50 (1.OO = 90KVA). External Power Load. The BPCU provides a dc voltage output to both EICAS computers proportional to the external power load. The BPCU senses external load from the ground power current transformer. The ac load for main ac, ground service and ground handling buses is displayed for values between 0/0.1 to 1.50 (1.00 = 90KVA) on the EICAS ELEC/HYD maintenance page. AC Voltage and Frequency. For each main power source (IDG, APU generator, EXT PWR, and HYD MOTOR GEN) the voltage and frequency are sensed from phase B. The singlephase output of the static inverter is sensed to display voltage and frequency. All signals are supplied to both EICAS computers except the APU GENERATOR (L computer only) and HYD MOTOR GEN (R computer only). Indications are displayed on the EICAS ELEC/HYD maintenance page. AC voltage and frequency are displayed between 0/100 to 130 volts ac and 0/380 to 420 Hz.

AC POWER INDICATION EFFECTIVITY ALL

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B767 200-300 BOOK 24 101 - Electrical Power

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