Electrical Power Flashcards
What do we check before turning the Aircraft Power Supply off?
ADIRUs, Emergency Light S/W etc. must be turned off
What is the purpose of Static Inverter (SI)?
Converts DC to AC
What is the purpose of Transformer Rectifier Unit (TRU)?
Converts AC to DC
What is the purpose of the HOT BAT BUS?
It is directly connected to the battery and all the users connected will always have
power available
Who supplies the AC ESS BUS?
AC BUS 1
When the AC BUS 1 is broken, who supplies the AC ESS BUS?
AC BUS 2 through the AC
ESSENTIAL FEED
When our GEN 1 is broken who supplies our AC ESS BUS?
It still the AC BUS 1 but the source comes from GEN 2 by passing through AC BUS TIE
When does the Emergency Generator operates?
When no other generators (normal power source) is available during flight
Who operates the Emergency Generator?
Ram Air Turbine (RAT)
When only the EMER GEN power source is
available, what buses is the only ones left
operating?
AC and DC ESS BUS
How do we charge the batteries of the Aircraft?
Is only possible when power is supplied by the generators and the battery S/W is turned on
What are the GCU functions?
Regulation, Protection, Switching
What are the parameters does the GCU regulates?
Frequency and Voltage
How do we increase the voltage by GCU?
Exciter Current
What does it mean when the AVAIL light is
on in the cockpit?
The EPU is connected to the aircraft
and it is ready to use.
What does it mean when the NOT IN USE light is on in the control panel below the
aircraft?
The EPU is connected but the EXT PWR P/B S/W is not pressed by the pilot
What is the meaning of IDG at its purpose?
Integrated Drive Generator and it is a combination of Constant Speed Drive (CSD)
+ Generator
Four types of AC Consumers?
FIRST – Single Phase (115V) Consumer with
low power demand.
SECOND – Single Phase Consumers that needs a different voltage (28V or 26V) by
using Step down Transformers
THIRD – Three Phase Consumers such as 3 phase motors and TRU and all needs to operate at the same time
FOURTH – Large load that need about 50% of the total electrical load
What do we do to the Large Loads consumers when there’s a power outage?
Shed
Shed is done by?
Automatically or Manually
How do we do the Manual Shedding?
By pressing the Gally P/B S/W (Airbus) or L/R Utility P/B S/W (Boeing)
How do we protect the Wiring System?
By using Fuse or Circuit Breakers
What is the advantage of CBs over Fuse?
The CBs trip when there’s a short circuit/fault in the system and can be reset when the repair of the wiring system is done while the Fuse wiring system trips but after
tripping, we need to replace it.
If Battery Source is the only source left, what BUSES is the BAT 1 and BAT 2 dedicated?
In EMER Situations: BAT 1 for AC ESS BUS and BAT 2 for DC ESS BUS
In Normal Situations: BAT 1 for Main Users and BAT 2 for APU Starter Motor
What are the Loads Shed able?
Galley (Airbus) and Utility (Boeing)
What is the power supply for GCU?
Permanent Magnet Generator (PMG)
What are the influences to modify Frequency?
By the Rotational Speed of the Rotor and By the number of rotating pole pairs
The frequency of the VFG is not constant, so how do we meet the required Frequency?
It depends on the speed of the related engine
If there’s a over voltage or over current, what does the pilot do?
Pressing the IDG 1/IDG 2 P/B S/W on the overhead panel
If we press the IDG 1 P/B S/W, what will happen?
The GEN 1 will disconnect from the Engine Gearbox
How do we reconnect the GEN 1 to the Engine Gearbox?
By pulling the Reset Ring below the section of the engine and inside the fan cowls.
A kind of Power Relay wherein it operates for as long as the current flows?
Contactor
Where is the Maintenance Bus S/W is located?
In the Cabin Ceiling Panel, before entering the Cockpit
What illuminates when the External Power
Unit GPU is connected?
“Connected” and “Not in Use”
What do we do to make sure the batteries will not discharge?
At least 1 Source that can Charge the battery and the Batt S/W is turned on
WHAT IS THE DIFFERENCE BETWEEN A VARIABLE GENERATOR AND AN IDG?
VARIABLE GENERATOR - VARYING FREQUENCY OR SPEED IS NOT CONSTANT
IDG - CONSTANT FREQUENCY DUE TO CONSTANT SPEED DRIVE?
WHAT BUS DOES POWERED BY EMERGENCY GENERATOR?
EMERGENCY BUS
THE IDG 1 FAILED? WHAT WOULD BE THE POSSIBLE SCENARIOS?
MANUALLY OPEN THE BUS TIE SWITCH FOR THE IDG 2 TO SHARE POWER
IS THE BTB THE EQUIPMENT THAT WILL POWER AC BUS 1?
BTB IS USED TO ISOLATE BUS 1 AND BUS 2 FOR INDEPENDENT PARALLEL OPERATIONS… PERO PAG FAIL.YUN 1 MAG TAKE.OVER.YUN ISA VIA BTB…
WHEN GEN 1 FAILS, WHAT BUS POWERS AC ESSENTIAL.BUS?
STILL AC BUS 1 BUT POWER COMES FROM GEN 2 THRU BUS TIE
When does the RAT or ram air turbine deploys?
Total loss of power supply
What is the purpose of Static Inverter (SI)?
Converts DC to AC
What is the purpose of Transformer Rectifier Unit (TRU)?
Converts AC to DC
What does it mean when the AVAIL light is on in the cockpit?
The EPU is connected to the aircraft and it is ready to use.
What does it mean when the NOT IN USE light is on in the control panel below the aircraft?
The EPU is connected but the EXT PWR P/B S/W is not pressed by the pilot
What do we do to the Large Loads consumers when there’s a power outage?
Shed
Shed is done by?
Automatically or Manually
What illuminates when the External Power Unit GPU is connected?
Connected” and “Not in Use
Why is there a small pin in the receptacle?
For correct installation and to prevent arching
What is the meaning of IDG at its purpose?
Integrated Drive Generator and it is a combination of Constant Speed Drive (CSD) + Generator in one housing
When does the Emergency Generator operates?
When no other generators (normal power source) is available during flight
What are the parameters does the GCU regulates?
Frequency and Voltage
