Electrics and Lighting Flashcards
DC Power Sources?
2 batteries, 2 DC Gens and 2 TRU’s
AC Power Sources?
2 AC Gens and 3 Inverters
What happens when the Battery Master is turned on?
Mainly, it connects the batteries to the L and R ESS Bus. It also energizes the Main and Aux switches, allowing them to function.
What happens when the Aux Battery switch is turned on?
It connects the Aux Battery to the L ESS BUS and allows it to charge from the Left Main Bus.
What is the primary function of the Main Bus Tie switch?
Main function is to connect the Left and Right Main Bus together. This is primarily for engine starts, but can be checklist directed.
Loss of one TRU will cause what?
Loss of one TRU will cause the Secondary Bus Tie to close, allowing the remaining TRU to power both sides.
Loss of one DC Gen will cause?
Loss of one DC Gen will, if the BBPU allows, the Main Bus Tie to close.
If BOTH DC Gens are lost?
If two DC Gens are lost, the Main/Secondary Bus Ties (L and R) will close, Nothing has been lost at this point.
If a fault exists on a DC Bus, what happens?
If a fault is found by the BBPU, it will initially inhibit Bus Tie closure and try to isolate the fault. If the fault continues, it will remove the affected Bus from service by taking the Gen and the battery offline.
Can a faulted DC Bus be reset?
Yes, the BBPU reset switch use will be directed by the E&A Checklist.
Which Bus does the APU power?
The APU powers the right main bus.
What do the inverters do?
They take 28v DC power and convert it into 115v Fixed AC power. The instruments and communications equipment are the consumers of this power.
