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.