Electrical Flashcards
ACPC
AC Power Center
GCU’s
Generator Control Units
2 IDG’s rated at:
40 KVA, 115 VAC, 400 Hz; up to FL410
APU rated at:
40 KVA, 115 VAC, 400 Hz; up to FL410
ADG rated at:
15 KVA, 115 VAC, 400 Hz
GCU protection removes generator output for:
- over/under voltage
- over/under frequency
- generator or BUS overcurrent
- generator phase sequence
Purpose of IDG’s
Convert variable N2 speed to constant 12,000 rpm gen. speed
IDG FAULT switchlight indicates:
High oil temp. OR low oil press. within IDG
IDG DISC switchlight indicates:
IDG disconnected (automatically or manually)
Once disconnected, can an IDG be reconnected in flight?
No
What is the primary source of AC electrical power?
IDG’s
Where is the AC external power receptacle located?
Forward right side of aircraft
What type of batteries do we have?
Nicad (nickel cadmium)
Where are the batteries located?
Nose compartment (main) Aft equipment bay (APU)
TRU’s
Transformer Rectifier Units
How many TRU’s?
4 (nose compartment)
- TRU 1
- TRU 2
- ESS TRU 2
- ESS TRU 1
What is overvoltage protection rated at?
45 KVA for 5 minutes
60 KVA for 5 seconds
How is the oil cooled?
Fuel/oil heat exchanger
When will the IDG switchlight FAULT lamp illuminate?
Oil overheat/underpressure
How is the IDG separated from the accessory gearbox when the DISC switchlight is pressed?
Electrical solenoid
What are the 2 ways the IDG can disconnect?
Mechanically, or by shearing of the driveshaft
What do the GCU’s & ACPC provide?
Bus priority & protection during normal/non-normal ops
What are the reasons a generator is taken offline?
- over/under voltage
- over/under frequency
- generator & bus over current
- generator phase sequence
What must be present for the green AVAIL portion of the AC - AVAIL/IN USE switchlight to illuminate?
External power must be the correct:
- voltage
- frequency
- phase
What happens when pressing the external AC switchlight?
AC service bus is powered directly (backdoor) & aircraft is in the Service Configuration
What distributes power to the AC busses?
ACPC
What is the ACPC’s priority logic?
Onside
Inside
Offside
Outside
Where does AC ESS BUS derive its power in the event of total AC power loss?
ADG Bus
After AC power loss & re-establishment of generator power, what button must be pressed in order for AC ESS Bus to reconnect to the system?
PWR TXFR OVERRIDE button (bottom center pedistal)
What does the AC Service Bus provide power for?
Service outlets for pax cabin U lavatory cleaning
Is the ADG normally deployed automatically?
Can it be deployed manually?
Yes
Yes
What does the ADG power?
- slats/flaps
- pitch trim
- hydraulic 3B pump
- AC ESS BUS
How many DC busses?
9
- DC BUS 1
- DC BUS 2
- DC ESS BUS
- DC SERV BUS
- DC UTIL
- DC BATT BUS
- DC EMERG BUS
- MAIN BATT DIRECT BUS
- APU BATT DIRECT BUS
What are the TRU’s rated at?
120 amps
How many volts do the TRU’s create?
28 VDC
What is normal output of the main battery?
24 VDC, 17 amp hours
What is normal output of the APU battery?
24 VDC, 43 amp hours
What powers the main battery charger?
What powers the APU battery charger?
AC BUS 1
AC SERVICE BUS
The batteries are capable of supplying approximately ___ minutes of DC emergency power.
30
Max TRU load?
120 amps
Max time for operations with battery power only?
5 minutes
How many generators?
4
How are the TRU’s cooled?
Individual fans
What controls the DC tie contactors?
DCPC
Can the TRU’s be turned off?
No
What busses are powered when the Battery Master switch is turned on?
Main battery direct bus
APU battery direct bus
DC battery bus
