Electrical System Flashcards
What buses are powered when the BATTERY MASTER is selected on?
Left and Right Essential
What buses are powered when BATTERY MASTER and MAIN BATTERY switch are selected on?
Left and Right Essential and Right Main
What buses are powered when the BATTERY MASTER, MAIN BATT, and AUX BATT switches are selected on?
Left and Right Essential and Right Main
With the BATT MASTER, MAIN and AUX BATT switches on, what must be selected to power the left main bus?
MAIN BUS TIE
When do the AC generators come on line?
Engine running and condition levers in the MIN to MAX range
What buses are powered the APU generator powered?
All DC Buses
What buses are owered with the DC external power?
All DC Buses
What will happen if the DC External power voltage exceeds 31.5 volt?
DC External power is automatically disconnected from the system
What buses are powered with the AC external power?
All AC and DC buses
What controls the 4 bus ties?
DC Logic
What is the maximum DC generator load, ground and in flight?
0.7 ground and 1.0 in flight
What is the purpose of the TRU’s?
Convert 3 phase 115 volt variable frequency AC to 28 volt DC
What is the maximum TRU load?
200 amp each
What is the minimum TRU voltage?
25 volts, below 18 volts caution light indicates a TRU failure
What is the maximum AC generator load ground or in flight?
Temps below 10 C is 1.0 and above 10 C limited to .33
What does a battery load indication of +1.05 indicate?
Overcharging by 5% over maximum charge rate
What is the maximum output rating of the DC generators?
300 amps
What is the maximum output rating of the TRUs
200 amps
When does the BBPU - Breaker Bar Protection Unit react to a main bus fault?
High generator output over 450 amps
What does the BBPU do when it detects a main bus fault?
Opens the ties and isolates the affected bus
How many inverters are there?
three
What is the purpose of the inverters?
Converts 28 volt DC to 115 volt single phase AC
What are the step down transformers for?
Convert 115 V AC to 25 V AC
What is the indication of a failure of the 26 V AC or the 115 V AC bus?
Caution light illuminates for 26 V AC but no indication for the 115 V AC failure
What will happen if an inverter fails?
Parallel control box disconnects failed inverter and related caution light comes on and the remaining inverters provide necessary power
What is the indication of a fault on the battery temperature display sensor and the over temperature sensor?
Amber light comes on at the 60 degree point, over temperature SENSOR FAIL light comes on
Will all buses be powered if DC generator fails?
Yes, DC Logic closes appropriate (Main) bus tie
Will all buses be powered if both DC generators fail?
Yes, DC Logic closes appropriate bus ties and power comes through the TRUs
What action should be taken as per the QRH with a double DC generator failure?
1 and 2 Generator Reset, Batteries off, Master off, Land as soon as possible
What will occur if a subsequent TRU fails after losing both DC generators?
Total power failure, loss of cabin pressurization, battery on, descend and land as soon as possible
Will all buses be powered if a TRU fails?
Yes, DC Logic closes appropriate bus ties
Will all buses be powered if both TRUs fail?
Yes, DC Logic closes appropriate bus ties
Will all buses be powered if an AC generator fails?
Yes, Other AC Gen takes up the load
Which battery is the Hot battery bus connected to?
Main (Right) Battery
Can the BBPU disconnect the main bus tie if the main bus tie switch is on?
Yes
