PTM Ch. 2 Electrical Power Systems Flashcards
What volt DC system do we have?
28 V DC
What AC voltage do we use?
26 and 115 V AV
What kind of batteries do we have?
Lead acid
What is AC power used for?
Flight instruments and avionics
What essential bus do the inverters run off of?
No 1: left
No 2: right
What are the transferable items from the left essential bus to the right essential bus?
- Fuel crossflow valve
- Surface deice boots
- Landing gear control
- Landing gear position indicator
- Cabin pressure dump
- Left engine intake heat
- Right engine intake heat
- Windshield heat
- Turn and slip
- Pilot instruments
Should you test the voltage of the batteries with the battery switch on?
No. It’ll show the highest voltage of any power source connected.
What should you do prior to turning the batteries on?
Reset the battery switch.
What should you do before turning the generators on?
Reset the generator switch.
What two conditions must be satisfied for the battery fault detection circuit to be operative?
- At least one battery switch must be on
- Either both generator switches must be on
Or
Left generator switch must be on and GPU plug must be in the external power receptacle
How much DC voltage does the generator put out?
28 V DC
What is the permissible generator continuous load except during generator assist starts and during battery recharging after engine start?
300 Amps
Not to exceed 2 minutes
What are the six features of the GCU? Only very good rabbits gain riches.
- Over voltage
- Voltage Regulation
- Generator Paralleling
- Reverse Current Protection
- Ground Fault Protection
- Relay Control
What does placing the generator reset do?
Reset the protection circuit if the fault no longer exists
What is the max load during cross starts?
100 Amps
What can happen if you shutdown an engine without turning off the respective generator?
Blow the 325 Amp limiter circuit breaker
Where is the GCU located?
In the respective wheel well
How to perform current limiter check
- Turn off both batteries and one generator.
- Press the test button on the annunciator panel
- If panel test is normal all 3 DC busses are powered and the current limiters are intact.
When should current limiter check be done?
After cross generator start
What amp limitation do we have on GPU’s?
1000 amps
Where is the battery bus located?
Junction box, behind captain’s seat
How many inverters can be used at any time?
One
What is the acronym to remember all 10 items that are transferable from the left essential bus to the right essential bus?
I- Instruments (pilot’s) and turn-and-slip
F- fuel crossflow valve
P- pressurization dump
I- ice equipment (surface deice, left and right engine intake heat, left windshield heat)
G- gear (landing gear control and landing gear indication)
Where are the inverters located?
In the back on the rack.
What does both AC Annunciators mean?
Loss of inverter. Switch to the other inverter
What does 1 AC Annunciator light mean?
The 115 AC bus tie circuit breaker popped.
The 115-VAC and 26-VAC bus tie circuit breakers located where?
On the nonessential bus even though they’re not powered by the nonessential bus.
The generators are limited to what amperage below 1000’ for what reason.
200 amps because of cooling