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GENERATOR DRIVE -FUNCTIONAL DESCRIPTION
The APU oil cools the APU generator.
See the APU and generator lubrication system section for more information (SECTION 49-27).
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GENERATOR DRIVE -FUNCTIONAL DESCRIPTION
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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
AC GENERATION -INTRODUCTION
General
The AC generation system supplies 115v ac power to the airplane. The ac generation system has these sub-systems:
*
IDG power
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APU generator power
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Backup generator power.
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AC GENERATION -APU GENERATOR AND IDG POWER SYSTEMS -GENERAL DESCRIPTION
General
The IDGs and APU generator supply 115v ac, 400 Hz power to the left and right main ac buses. See the generator drive section for more inforation about the APU generator and the IDGs (SECTION 24-10).
APU Power
The APU generator supplies power through the APB to the tie bus. Power goes from the tie bus, through the BTBs, to one or both main ac buses.
The APU generator supplies power through the GSSR to the ground service bus. The APU generator also supplies power through the GHR to the ground handling bus.
The APU generator has a GCU that controls, monitors, and protects the APU power system. The APU GCU gets an input from the APU generator (APU GEN) switch. When the switch is in, the GCU automatically controls the APB. When the switch is out, the GCU opens the APB and trips the field of the generator. The OFF light comes on when the switch is out, or when the APB is open because of a fault.
IDG Power
The left IDG supplies power to the left main ac bus. The right IDG supplies power to the right main ac bus. Power goes through the GCBs.
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There is a GCU for each IDG. The left and right GCUs control, monitor, and protect the IDG power system. Each GCU gets inputs from a generator control (GEN CTRL) switch and a BUS TIE switch.
When the GEN CTRL switch is in, the GCU automatically controls the GCB. When the switch is out, the GCU opens the GCB and trips the field of the generator.
When the BUS TIE switch is in, the GCU automatically controls the BTB. When the switch is out, the GCU opens the BTB.
The GCU turns the switch light (ISLN or OFF) on for each switch when the switch is out, or the breaker is open because of a fault.
No-Break Power Transfers
The BPCU coordinates power transfers between the APU generator and IDGs. The BPCU and GCUs communicate on the systems ARINC 629 buses.
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AC GENERATION -APU GENERATOR AND IDG POWER SYSTEMS -GENERAL DESCRIPTION
When the ac system changes from one power source to another in the air, it does break power transfers. On the ground, it does no-break power transfers. The system momentarily connects two power sources to one bus so there is no interruption in power. A GCU electronically adjusts an IDG speed to match the power of the two sources to do a no-break power transfer. For transfers between external power and the APU, the APU controller adjusts the APU speed to do the no-break power transfer. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 电源 Electrical Power(21)
