ORAL* E145 Electrical Flashcards
Is Airplane predominately AC or DC?
DC
How many generators are there?
4 engine, 1 APU
When generators are on number 1 engine?
1 and 3
Which generators are on the right engine?
2 and 4
Max amperage on Engine Gens?
400 amps
Max amps draw APU?
400 amps up to 30k…300 amps 30k and above
Battery Voltage and amps?
24 volt, 44 amps nicad
Where are batteries
Front electronics compartment…left side
Does Ground Power charge batteries?
No
Minimum battery temp for APU start?
-20c
Backup battery volts and amps
24 volt 5 amp lead acid
Inverter Specs?
250 VA/400 hz single phase…output 115 VAC
What bus powers inverter?
DC bus 1
what is the EDL?
Electrical Distribution Logic…controls tie contactors
All 4 generators are online…what are positions of bus tie contractors?
Bus tie 1 is open (off) and Bus tie 2 is closed (on)
GEN OVLD caution happens when?
Greater than 400 amps
GPU should supply at least ______amps?
300
If GPU is connected and on what light is on?
GPU AVAIL
What should GPU voltage show on MFD when connected and availbale>
26-29 VDC
Which has priority…Generators or GPU?
GPU takes over when connected
Which bus is powered with batteries OFF and GPU selected?
Ground Service Bus
What is powered by Ground Service Bus?
LIGHTS...... Stair Lights Dome Light Galley Lights Cabin Lights, Lav Lights Baggage and Service Compartment Lights
what is an electrical emergency?
Loss of all generators
Batteries can supply essential power for how long?
40 minutes…includes 3 APU start attempts
In Normal ops…battery 1 is connected parallel with GENS
1 and 3
Battery 2 normally runs in parallel with GENS
2 and 4
Which battery starts the APU
Battery 2
What happens to battery 1 during APU start?
It’s isolated Battery 1 contactor opens
Battery AUTO switch does what?
Battery contactors controlled by the EDL
GPU is connected and selected on…what do battery contractors do?
OPEN….they disconnect the batteries. Batteries cannot be charged with GPU
with battery power only on ground, do you have shed busses?
No
How can you connect shed busses on ground?
SHED BUSES OVRD and at least one generator
BATT OVTEMP happens when
More the 70 C
Batteries less than 24v after APU start…what’s required?
APU must run 30 minutes to recharge
What does Back Up Battery on Overhead panel do?
Backup Battery charging…
when do EDG come on line?
56.4 N2
How many gen resets?
1
What 3 electrical sources can start APU?
GPU, Battery 2, or Battery 2 with Main gen assist
What does backup battery power?
Backup hot bus, which includes the 5 GCU’s and the EDL
Can battery 1 start APU?
no
APU powers which bus?
CENTRAL DC
When does APU come on online?
95% plus 7 seconds
On ground when are all DC buses on?
a. At least 3 gens. online
b. GPU on and connected
c. One generator running and SHED OVRD
Explain electrical config with 4 or 5 generators online
Left and right networks are isolated and all buses are energized
Explain electrical config with 3 gens online
one network connected through bus tie contactors which are closed…all buses eneergized
Explain elec configuration with 1 or 2 gens online
Same as with 3 but shed buses drop out (one network, bus tie contactors both closed)
electrical emergency…no generators (in flight)
Batteries only power Essential Euses only
Which displays still work in emergency power?
EICAS, RMU 1 and 2, and the ISIS
what do avionics master buttons on overhead do?
Allow shutting off radios and nav during APU start to avoid spikes
Inverter Powers what?
TCAS, EGPWS
BTC 1 position with Gen 1 fail and APU off
closes
BTC 1 portion with Gens 1 fail and APU on
opens
What do you do is auto transfer fails with a loss of all generators?
Push Essential Power button
How do you know if automatic transfer fails with a loss of all generators?
Displays still work
What does Essential Power button do?
Overrides EDL, and makes sure batteries are only powering the essential buses
What does SHED BUSES OVRD do?
closes shed buses contactor
Will SHED BUSES OVRD work in flight?
Nope
What does BUS TIES OVRD do?
Closes BTC’s except in overcurrent
When is APU not seen on MFD
APU off and less than 10% RPM
If airplane will sit for long period what are battery considerations
Remove if temps below -15c, and batteries must be removed to recharge if volts are below 19VDC