Electrical Flashcards
How can external power be used by the ground crew when the cockpit door is locked?
Press the AC PUSH switchlight on the external service panel
What might the DC Service switch be used for?
External aircraft lights while repositioning the aircraft without the battery master on
In the aircraft with no power switched on, which buses are powered?
APU Direct Bus
Main battery Direct Bus
EMER bus
How many volts must be present prior to APU start?
22 volts minimum
What is the time limit on battery power without the APU or external power and why?
5 minutes to prevent over heating the CRTs without the cooling fans
How many AC buses are there?
4
How many DC buses are there?
9
What normally powers AC bus 1 & 2 and what is the switching priority in an abnormal situation?
GAGE
G onside generator
A APU
G offside generator
E external power
How many TRU’s are there and what is their maximum power rating?
4 rated at 120 amps , 28 VDC
How many DC bus ties are there and what are their names?
5
The main tie Cross tie Utility tie Essential Tie Essential TRU tie
If the cross tie closes, what else will close
The main tie and essential tie will always close if the cross tie closes
When is the DC utility bus shed?
When the main tie or cross tie closes
What items are on the utility bus?
The passenger service units (Primarily reading lights)
How are the DC bus ties controlled?
Automatically
DC bus tie control is automatically accomplished through the 2 DC power centers (DCPCs)
When will the ESS TRU 2 TIE close (causing it to display on the DC synoptic page)
with the loss of AC Bus 2 and ESS True 1
What does the DC ESS bus primary provide power for?
The captains flight instruments
When will the ADG automatically deploy?
During a complete AC Power failure
What buses are powered by the ADG?
The ADG bus, AC essential bus, and the DC battery bus
What items are powered by the ADG?
HEFAS
Hydraulic pump 3B Essential AC bus Flaps and slats @ half speed ADG bus Stab trim channel 2
How much power does the ADG produce?
115 volts, 15 kVA
What is the minimum airspeed for ADG operation?
135 KIAS
why must the ADG handle be pulled after an auto deployment?
Because you will loose DC Essential bus power if you dont
after landing with weight on wheels internal logic will cause the loss of power to the DC ESS bus if the handle is not pulled
As the aircraft slows below 135 KIAS on approach, the ADG will no longer be able to generate sufficient power for operation. The DC ESS bus will continue to be powered through the batteries, but after landing with weight on wheels internal logic will cause the loss of power to the DC ESS bus if the handle is not pulled
How is normal power restored after an ADG deployment if a generator returns?
By stowing the ADG handle and pressing the PWR TXFR OVERRIDE button
Can hydraulic pump 3B be deselected after an ADG deployment?
No. It is hardwired to the ADG bus for continuous operation
