Electrical Flashcards
Describe the AC electrical system
Two engine driven 115 VAC, 400 hz 3-phase 40 KVA Intergrated Driven Generators provide AC power. APU generator is capable of providing AC power if engines are not running and an ADG is capable of providing emergency power
Describe the DC electrical system
Four Transformer Rectifier Units convert 115 VAC power to 28-VDC power for distribution to the airplanes DC system
Describe the batteries
24 volt APU battery rated at 43 ampere hours and 24 volt main battery rated at 17 ampere hours
Electrical Power Panel:
DC Service switch
Connects the DC service bus to the APU battery direct bus
Electrical Power Panel:
Battery Master Switch
Connects the battery direct buses to the battery bus
Electrical Power Panel:
What does illumination of AVAIL mean on the AC switchlight
External power is connected and usable (correct phase, voltage and frequency)
Electrical Power Panel:
What does illumination of IN USE mean on the AC Switchlight
External power is supplying power to the AC buses
Electrical Power Panel:
IDG 1 and 2 DISC Switchlight (Guarded)
What happens when pressed in
The respective IDG is separated from the accessory gear box. The White DISC light will illuminate
Electrical Power Panel:
IDG 1 and 2 DISC Switchlight (Guarded)
What does illumination of amber FAULT light mean
High oil temp or low oil pressure is detected in the IDG (HOT LOP)
Electrical Power Panel:
IDG 1 and 2 DISC Switchlight (Guarded)
What does the illumination of the DISC light mean
The switchlight has been pressed disconnecting the CSD (constant speed drive) or the CSD has disconnected due to overtorque or temp
Electrical Power Panel:
AC ESS XFER Swtichlight
What happens when pressed
It illuminates and transfers AC ESS bus from AC bus 1 to AC bus 2. Will automatically transfer if a fault is detected on AC bus 1, illuminating the switchlight
Electrical Power Panel:
What does the OFF/RESET position on the Gen1,2 and APU switch mean
Disconnects the generator from its bus and re-arms the generator control circuit
Electrical Power Panel:
AC AUTO XFER switchlight
what does the illumination of the amber FAIL light indicate
Either an AC bus fault, or an over-current condition has occured and the respective bus has been isolated (AC bus 1 or 2)
Electrical Power Panel:
AC AUTO XFER switchlight
What does the illumination of OFF indicate
When pressed the light illuminates indicating that the respective bus has been isolated (manual cross-tie lockout)
ADG Auto Deploy Panel:
Unit switch; tests the transfer relays and the controller logic. What conditions must be met prior to conducting the UNIT test
Both engine generators must be online and both AC buses powed
ADG Auto Deploy Panel:
Unit switch test light; when illuminated what is indicated
Indicates a successful unit test
ADG Auto Deploy Panel:
PWR TXFR OVERRIDE Switch
Removes ADG power from the AC essential bus and allows normal power from AC bus 1 or 2 to the AC essential bus
How can external power be used by the ground crew when the cockpit door is locked
Press the AC PUSH switchlight on the external service panel
What might the DC Service switch be used for
External aircraft lights while repositioning the aircraft without the battery master on
In an aircraft with no power switched on, which buses are powered
APU and main battery direct buses, and the emergency bus
How many AC buses are there
Four
How many DC buses are there
Nine
What normally powers AC bus 1 & 2? And what is the switching priority in an abnormal situation?
GAGE G Onside Generator A APU G Offside Generator E External Power
How many TRU’s are there and what is their maximum power rating?
4 rated at 120 amperes 28 Volts DC
