Electrical Flashcards
When does the DRIVE light illuminate on the IDG panel?
-IDG Failure
-engine shutdown
-IDG Automatic disconnect
-IDG disconnected with the DISCONNECT switch
How much power is produced by the engine generators?
115v, 400 Hz
What does it mean when the TRANSFER BUS OFF light is illuminated?
Indicates that the related transfer bus is not powered.
What is a TRU?
Transformer rectifier unit
It converts AC power to DC power
Under what conditions will the TR UNIT light illuminate?
On the ground for any TRU failure
Inflight, TR1 has failed or both TR2 & TR3 have failed
The Cross Bus Tie Relay opens automatically:
- At glideslope capture with the flight director or auto pilot selected to ILS approach
- BUS TRANSFER switch selected to off
What powers the AC STANDBY BUS?
Main power source is AC TRANSFER BUS 1
The secondary source is from the MAIN BATTERY through the STATIC INVERTER.
Where does the DC STANDBY BUS receive power from?
TR1, TR2, & TR3
What happens if power is not available from the TR’s in regards to the DC STANDBY BUS?
The DC STANDBY BUS can be powered directly by the battery
What type of battery is there?
A single 24v DC nickel-cadmium battery
What is the normal battery voltage range
22-30 volts
The battery charger has two modes of operation:
A charge mode (when battery voltage drops below a predetermined limit
A transformer rectifier mode (completion of the charge cycle, it reverts to constant voltage TR mode. To keep the battery at full capacity
The battery charger charges loads connected to which buses?
Hot battery Bus and Switched Hot Battery Bus
If power is lost to AC TRANSFER BUS 1 or the source of power to DC BUS 1 what can power both the AC and DC STANDBY BUSES?
The battery charger
How long can a fully charged battery supply standby power for?
A minimum of 30 minutes
Which busses comprise the standby power system
HOT BATTERY BUS
SWITCHED HOT BATTERY BUS
BATTERY BUS
DC STANDBY BUS
AC STANDBY BUS
All generators inop, equipment available: Airplane general
Standby compass light
White dome lights
Emergency instrument flood lights
Flight crew oxygen
Pax oxygen
All generators inop, equipment available: Air systems
Air conditioning pack valves
BLEED TRIP OFF LIGHTS
Manual pressurization control
Altitude warning horn
PACK TRIP OFF lights
All generators inop, equipment available: Anti-ice
Captains pitot probe heat
All generators inop, equipment available: Communications
Flight interphone system
Service interphone system
Pax address system
VHF 1
All generators inop, equipment available: ELECTRICAL
STANDBY POWER OFF light
When does the STANDBY PWR OFF light illuminate?
Illuminates if the AC STANDBY BUS, DC STANDBY BUS, or BATTERY BUS is not powered.
What does the blue GRD POWER AVAILABLE light indicate?
External power meets aircraft quality standards
What does the blue APU GEN OFF BUS light indicate?
The APU is running and not powering any AC Transfer Bus.
Which of the following causes the DRIVE light to illuminate?
IDG oil low oil pressure or under frequency condition
What is the purpose of the Bus Tie Breakers?
Auto control AC power distribution
What is the purpose of selecting the BUS TRANSFER switch OFF?
- To inhibit Bus Tie Breaker auto switching
- To open the cross bus tie relay
An illuminated STANDBY PWR OFF light indicates a power loss to which bus?
DC STANDBY BUS
BATTERY BUS
AC STANDBY BUS
The guarded STANDBY POWER switch powers what when in Auto ?
In flight or ground, and AC transfer busses powered:
- AC standby bus is powered by AC transfer bus 1
- DC standby bus is powered by TR1,2,3
In flight or ground, loss of all AC power:
- AC Standby bus is powered by Battery through static inverter
- DC standby bus is powered by battery
- Battery bus is powered by battery
The guarded STANDBY POWER switch does what when in the Off position?
- STANDBY POWER OFF light illuminates
- AC standby bus, static inverter, and DC standby bus are not powered
The guarded STANDBY POWER switch powers what when in The BAT position?
- powers AC standby bus through static inverter
- powers dc stand by bus and battery bus directly from the battery
Generator drive and standby power panel: the generator drive “DRIVE” lights illuminate for what conditions?
DRIVE light is caused by a low pressure condition.
The light illuminated when:
- high oil temp (Auto disconnect)
- IDG failure
- Engine shutdown
- IDG disconnected through generator drive DISCONNECT switch
Generator drive and standby power panel: when will the STANDBY PWR OFF light illuminate?
One or more of the following buses are unpowered:
- AC STANDBY BUS
- DC STANDBY BUS
- BATTERY BUS
Generator drive and standby power panel: what do the generator drive DISCONNECT switches do?
- Manual disconnect if the associated IDG drive
- Disconnects IDG if electrical power is available and engine start lever in idle
AC/DC Metering Panel: what does the BAT DISCHARGE light when illuminated mean?
BAT switch is on and excessive battery discharge is detected.
AC/DC Metering Panel: what does the TR UNIT light illuminated mean?
On ground:
- Any TR failed
In flight:
- either TR1 failed or both TR 2&3 failed
AC/DC Metering Panel: what does the electrical ELEC light illuminated mean?
Only illuminates on the ground:
- A fault exists in the DC Standby power system or standby power system.
AC/DC Metering Panel: what does the guarded BAT switch do? How many positions does it have?
Two positions ( Off and On)
ON- turns the battery on, provides power to the :
- Hot battery bus
- Switched hot battery bus
- Battery bus
- AC/DC standby bus
- Static inverter
When in off position:
- prevents automatic switching of standby bus to battery power when normal el creo also power is lost
- Only hot bat bus will be powered
AC/DC Metering Panel: what does the GALLEY or CAB/UTIL switch do in its two positions?
When in on position:
- Supplies power to Galley 115v bus
- Broadband satellite system
- cabin recirc fans
- Logo lights
AC/DC Metering Panel: what does the IFE/PASS SEAT switch do?
When on supplies power to the broadband satellite system
When off removes electrical power from broadband satellite system
AC/DC Metering Panel: what checked limitations are there?
-On the ground limit one generator operation to a maximum 215amps
-Don’t remove AC power from aircraft for at least 30 seconds after IRS shutdown
- in flight reset of circuit should only be accomplished when directed QRH. Allow approx 2 mins before reset
