Electrical Flashcards
What type of circuit breakers does the E175 have?
Thermal and Electronic
What is the purpose of the TRU?
Convert AC to DC
What are sources of AC power?
IDG
APU
GPU
RAT
When can you start the APU during normal operations?
10 mins prior to pushback
Or as necessary for passenger comfort.
What is the minimum battery voltage for normal operations?
22.5 volts
Can you start and engine without AC power?
Yes.
What type of power does the IDG provide?
AC
What should happen during a total loss of AC power in flight?
The RAT should deploy and provide AC power to the AC Essential Bus.
What items can the hot battery bus power?
Fuel Panel
Engine Fire Fighting
How do you manually disconnect the IDG?
Place the control knob to the DISC position.
What are the sources of DC power?
DC GPU
Battery
What converts AC to DC?
TRU
How many TRUs do we have?
3
TRU 1, 2 and ESS
How do we check digital circuit breakers?
MCDU
How do we check thermal circuit breakers?
CB Panel
How much time do we have on battery power alone?
10 minutes
What are the electrical power priorities?
Onside - same side IDG
Inside - APU
Outside - GPU
Cross side - Opposite IDG
How long does it take for the RAT to deploy?
8 seconds
When do the RAT deploy?
When there is AC power interruption
What KIAS is required to spin up the RAT?
150 KIAS
What is the minimum airspeed to provide electrical power from the RAT?
130 KIAS
What equipment is on the DC Standby Bus?
Igniters
What AC bus is powered when only DC is available?
AC Standby Bus
What equipment is on the AC Essential Bus?
3221
3 HYD 3A
2 Fuel Pump 2
2 Slat ch 2
1 Flaps ch 1
When should you see cross side power?
Single engine taxi
What does the amber light indicate on the IDG panel?
High oil temp
Low oil pressure
What does the DISC setting on the IDG panel do?
Hard mechanical disconnect
After starting the left engine, with the APU what will power the opposite AC BUS?
APU
What will happen if you leave the GPU button pressed after being disconnected from external ac power?
The airplane will not allow you to reconnect until recycling the button
With a non annunciated aft cargo fire, how many times do you need to press the button to discharge the low-rate bottle?
3 times
- Arm
- High
- Low
When the captain calls “Flaps 1, APU off, flight control check” what should you do for a proper power transfer?
Wait 30 seconds after N2 stabilizes to shut down APU.
APU has a 1 minute cool down where it still provides electricity
During an electrical emergency, how many minutes power are the batteries capable of supplying?
10 minutes
If you see ELEC EMERGENCY EICAS how much time do you have?
RAT should deploy in 8 seconds
If you cannot deploy you have 10 minutes of battery
Can the RAT charge the battery?
Yes, the RAT can charger the BATT by converting AC to DC via TRU
What is piece of equipment has the biggest draw on the RAT?
HYD 3A
How does HYD 3A reduce draw on the RAT?
Unloader valve
Flow limiter
When would the IDG LEDs turn on?
HOT LOP
What does auto allow the IDG to do?
Allows for cross-side power
What are the airplanes power priorities?
IDG, APU, GPU, Cross-side IDG
If you turn the IDG to off then to auto will you get power
back?
Yes
If you turn the IDG to DISC then to AUTO will you get
power back?
No its a one time mechanical disconnect
What position does the GPU switch need to be in to
accept power?
Out
What is the normal position of the AC bus tie switch?
Normal position is auto
When do we take the AC bus tie switch out of auto?
When directed by a QRH procedure
What does auto allow the bus tie to do?
It allows bus ties to be open or closed
Where does APU GEN switch normally start?
In
Why does the APU GEN switch start in?
To allow APU to pick up power right away
What is the purpose of the TRU?
Convert AC to DC
How do we charge batteries in flight?
AC power is converted by the TRU DC inverter to charge the batteries
Which TRU will we use in electrical emergency?
TRU ESS
What does TRU ESS do for us?
Allows the RAT to charge batteries in electrical emergency
How long should it take to deploy the RAT?
8 seconds
How do we know when the RAT is operating?
BATT discharge goes away
When we still have the BATT discharge goes away what AC buss do we have?
AC STBY BUS
What is on AC STBY BUS?
Igniters
What is on AC ESS BUS?
3-2-2-1 Hydraulics 3A, AC fuel pump 2, Slat ch 2, Flap ch 1
Which battery can be differed easier?
BATT 2
APU FADEC on BATT 1, APU stater On BATT 2 - can be replaced with DC GPU
Why is battery 2 OFF/AUTO?
Auto allows power to be replaced by DC GPU
When DC is first applied what is available?
Screens 2/3
IESS
22.5 volts, no lower than 21.0 to charge, lower than 21.0 Call Mx
What page is available on MFD where there is only DC power?
Status
Can we move the plane while IESS is turning on?
No
How long does IESS take to warm up?
90 seconds
What happens when we have AC power established (1 of 3 things)?
Electrical PBIT (ACEs FCMs for out of tolerance conditions)
How long does E PBIT take?
3 minutes
How many ways are there to to interrupt the E-PIT
3 ( ac power, all hydraulic are pressurized, flight control mode switches)
Windshield power up PBIT
When will the power up PBIT begin?
When two AC sources are on.
Single engine taxi only one works
IRS begins alignment
How long does IRS alignment take?
Up to 17 minutes to align, can align in flight
Where is BATT temp displayed?
Electrical Synoptic Page
What should you do if you get a BATT Over Temp Message?
Memory item - Effected battery OFF
How do we convert DC to AC?
Inverters
When should you turn on ADS probe heat before engine start?
-18 C before FFOD, erroneous readings, contamination, less that 0 with visual moisture
What could erroneous ADS indications effect?
It could cause the E-PBIT to fail
How does starting an engine effect the ADS probe heat?
Starting the engine activates the ADS probe heaters
If they were pressed in prior to start, you need to turn them off because it inhibits
system logic and will turn the probes off.
ADS probe heat is always on when engine(s) are started
What COM/NAV equipment do we have durning an electrical emergency?
CA: NAV 1 IRS 1 CCD 1
FO: COM 2 MCDU 2
