STANDBY POWER -FUNCTIONAL DESCRIPTION -RAT GENERATOR CONTROL
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STANDBY POWER -FUNCTIONAL DESCRIPTION -DC CONTROL
General
The standby power system operates to control power from the hot battery bus to these buses:
*
Battery bus
*
Captain’s flight instrument bus
*
Battery bus #2.
The EEU controls these relays to control power from the hot battery bus:
*
Main battery relay
*
Battery-captain isolation relay
*
Ground power battery relay.
Main Battery Relay
When the main battery relay energizes, the hot battery bus can supply power to the battery bus. In general, the main battery relay energizes for these conditions:
*
Transfer bus power was available, but was lost (in the air, the P310 keeps the relay energized)
*
You manually select standby power on
*
The two center TRUs fail
*
TRU C1 fails and the captain-F/O bus tie relay energizes to restore power
*
Autoland bus isolation request
*
DC/standby self-check.
Battery-Captain Isolation Relay
The battery-captain isolation relay energizes to isolate the captain’s flight instrument bus from the hot battery bus (through the battery bus). This occurs when there is an autoland bus isolation request or for a dc/standby self-check.
Ground Power Battery Relay
When the ground power battery relay energizes, the hot battery bus can supply power to the battery bus #2. The ground power battery relay energizes for these conditions:
*
You push the battery switch on as part of initial power application
*
APU starting/running on the ground
*
When APU shuts down and the battery switch is off, the relay stays energized for 90 seconds. This makes sure the battery bus #2 has power to close the APU inlet door.
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STANDBY POWER -FUNCTIONAL DESCRIPTION -DC CONTROL
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777 AIRCRAFT MAINTENANCE MANUAL
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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
FLIGHT CONTROLS DC POWER -GENERAL DESCRIPTION
Purpose
The flight controls dc (FCDC) power system supplies power to the flight controls system.
General Description
There are three FCDC power supply assemblies (PSA):
*
Left
*
Center
* Right. These PSAs supply power to their related flight control buses. Power Sources
Each PSA gets power from many different sources. The PSA automatically selects which power source to use. Each PSA has a battery to supply power during power interruptions.
The left PSA gets power from these sources:
*
PMG L1
*
Left dc bus
*
Hot battery bus. The center PSA gets power from these sources:
*
PMG L2
*
PMG R2
*
Captain’s flight instrument bus
* Hot battery bus.
The right PSA gets power from these sources:
*
PMG R1
*
Right dc bus.
The PMGs are permanent magnet generators in the backup generator housing. Each backup generator has two PMGs that supply power to the PSAs. The PSA changes variable frequency ac power from the PMGs into 28v dc power.
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FLIGHT CONTROLS DC POWER -GENERAL DESCRIPTION
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FLIGHT CONTROLS DC POWER -POWER SUPPLY ASSEMBLY
General
The PSA supplies power to the flight control systems.
The PSA contains the FCDC bus. The FCDC bus supplies power to flight control LRUs. Power to each LRU goes through circuit breakers on the front of the PSA. You can remove power from an LRU when you open its related circuit breakers.
Training Information Point
Be sure to obey all of the cautions on the front of the PSA.
The left, center, and right PSAs are interchangeable.
The parentheses below a circuit breaker tells the PSA position in which that circuit breaker is active. For example, circuit breaker AUTO-SPDBRK (L,R) is only active when the PSA is in the left or right position.
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