Systems - Electricity Flashcards
What are three principles of Nicad batteries
1) Provide Linear Power
2) Susceptible to Thremal Runaway
3) Once they are completely discharged, they can’t be re-charged.
What kind and how many main batteries do we have and how long do they last on the ground with all items running?
Two 24 volt Nicad batteries. Last for 15 mins on the ground.
What are the principles of Lead Acid Batteries
- Power decrease will be gradual
- Not susceptible to Thremal Runaway.
Do we have any Lead Acid Batteries on the EMB-145
Yes, the backup battery is a 24 volt Lead Acid located in the fwd avionics compartment.
What does the term “wired in series” mean?
All items on that circuit are dependent on the others in order to work (ie old christmas lights, if one bulb is out, the others are out).
What does the term “wired in parallel mean”?
Items on the circuit are not dependent on each other to continue to operate. This is how aircraft are wired.
What is the purpose of the Circuit Breakers
They protect the item on the circuit and in turn protect the entire aircraft in case there is an over amp situation.
What do the numbers on the CBs represent?
Max amperage (draw) at which the breaker will pop open to protect the aircraft.
Does a Bus create or use energy? What is the purpose of a Bus?
They do not create or use energy. A bus is a distribution point for draw items and a “plug in” point for power (like a power strip).
Where do Buses get their power from?
Batteries when generators are not running. Generators when running and on line.
What are the power sources on the EMB-145
1) two 24 volt Nicad Batteries
2) one 24 Lead Acid backup battery
3) four 28 volt generators @400amps
4) one 400 amp APU (300 amps above 30k feet)
5) 1 GPU plug in available.
How many total amps do you have available in flight under 30,000’ if all generators and APU are operating? How many amps do you need?
2000 amps available. 300 amps needed.
What is an EDL
Electric Distribution Logic, the brain of the system that can see everything but does not do anything.
What is the primary goal of the EDL?
To create two networks with a primary and backup power supply (generator) on each one.
What will the EDL do if it cannot meet its primary goal?
Create one network with a backup generator on it.
In flight, If all generators go off line, what will the EDL resort to?
It will “protect the core” by shedding all buses except the essentials and hot buses.
What is the GCU
Generator Control Units - if the EDL is the “brains” then the GCU is the “hands”. The EDL tells the GCU what to do.
What are the only items that will be powerd by the backup battery?
EDL and GCU
What is the primary purpose of the central bus?
Provide a separation point for the two networks and provide a “plug in” point for the APU and GPU.
In the air, if you have more than 4 generators, how many networks and sched buses will you have
2 electrical networks and all services.
In the air, if you have more than 3 generators, how many networks and sched buses will you have
1 electric network and sched buses.
In the air, if you have only 1 or 2 generators, how many networks and sched buses will you have
1 electrical network and no sched buses.
In the air, if you lose all generators, what do you have?
An Electrical Emergency - the batteries supply essential buses only.
What happens with the GENs and Batts when the GPU is plugged in and selected
GENs will not be allowed to connect and batteries will not be charged (to prevent thermal runaway).
What is the status of the Hot Bus when the battery switch is off?
It remains HOT.
What are the Sched Bus over-ride rules
1) Only works on the ground
2) Does not work on Batteries only
3) Not Needed when on ground power.
What are the Sched Bus Knob positions and what do they do?
1) Override - connects shed buses (closes SBCs)
2) OFF - Forces sched bus open (Opens SBCs)
3) AUTO- manipulated by the EDL.
If you see GPU Avail on the button what does this mean? What if the button is stiped?
GPU Avail = plugged in but not selected and GD service Bus is powered.
Striped = GPU is selected and the sched bus 1 and 2 is available.
What items are powered by the Ground Service Bus
Lights and shit in the back.
When will the Generators come online?
Automatically at 56.4% N2 if healthy. (Will be Dark).
What are the varous positions on the Bus Ties Override Knobs and what do they do?
Over-ride - forces closed
OFF - Forced Open
Auto - Manipulated by EDL.
What do the Avionics master switches control? When should you turn them off?
Control images on the screen and should always stay on (Dark) unless directed by a checklist.
What does the A/C power button do
It takes the inverter offline and you will lose the A/C bus.
What items are powered off the A/C Bus?
1) EGPWS
2) ACARS Printer
3) Windshear Warning System.
What converts DC power to AC power on the EMB-145
Inverter
What does the backup battery button do?
Removes the backup battery from getting charged (when striped).
What battery is used to start the APU?
Battery number 2 alone (if starting APU after landing, batt 2 is assisted by ship GENs).
What is the status of the batteries when on Ground Power?
They are off line
When on the ground, what Logic does the EDL follow to send power to the passenger cabin?
1) With Ground Power
2) With 1 Generator (ie APU) and Shed Bus in Override
3) With 3 or more Generators on line.
Under what conditions will battery 1 and 2 work together to bring the APU back on line?
During an electrical emergency only
What type of items are on the essential BUS?
The essential ones, ie:
- Brakes
- Fadec
- EICAS
- RMU
What items Run off the HOT Bus #1
Fuel Shutoff Valve #1
Refuel Panel
ELT
Squib #1
Hydraulic Shutoff Valve
What items run off HOT Bus #2
Fuel Shutoff Valve #2
Coutesy Light (Cockpit dome light)
Airstair Door (if equipped)
Squib (#2)
Hydraulic Shutoff Valve
What are you doing when you push the Essential Power button? When would you push this button
You are forcing the aircraft into an electrical emergency in the event the automation does not do this for you.
You would push this button in the event you lost all 4 Gens and APU and Automation did not go into electrical emergency mode (ie PFD and MFD screens still running). Only do so after consulting QRH.
What BUS provides electrical power to the nose gear doors. What happens to the Gear doors if this BUS fails?
DC2, the doors will open if this BUS fails.
If armed, when will the emergency lights automatically light and how long will they last?
During an electrical emergency and last 15 mins.
What should you do to reset a generator, how many times should you attempt this?
Stripe and Unstripe it, you can only attempt this one time.
What is the minimum battery temp to start the APU?
-20°C
What are two important items on the Shed BUS that are important to operations?
1) You lose the taxi light
2) You lose the flashlight re-charging.
