ATA 24 Electrical Systems Flashcards
The BUS TIE relay will open when?
1) The AMC detects a different current value between the main BUSES
2) The Main Voltage drops below 12V
3) GEN1 or GEN2’s current difference is more than 75A
The BUS TIE relay will close when?
1) BATT MASTR switch to ENGAGE
2) BUS TIE SWITCH ON
3) Switch engine ON
With 2 Generators on, which BUSes are live?
ALL BUSES
With 1 generator offline, what BUS is offline?
The NON-ESS BUS
With 2 Generators offline, what BUS is offline
SHED BUS & NON-ESS BUS
The battery box contains what?
BAT HOT BUS, BR, EPR and BAT BUSS
The BAT BUS is connected to what?
The DIODE BOX 1&2 and the BUS TIE relays
The ESS BUS & AMC BUS take power from where?
The BAT BUS through the DIODE BOX
DIODE BOX 1&2 have power coming in from where?
The BAT BUS and MAIN BUS 1&2
Where are the BUS TIE’s located?
In the DISTRIBUTION BOXES
The EMERGENCY BATTERY is charged from where?
All 3 sources - The MAIN BAT, GENERATORS or EPU
Who has command, the BATTERY or the EPU?
The EPU through the control box.
The electrical system operates at what Voltage?
28.5V
The electrical system is designed to what principle?
A Duplex Parallel generation and seperation system.
What Voltage supply is the battery?
24V
If both generators and the main battery fail, what supplies the power?
The emergency battery to the emergency equipment.
What is acting as the return conductor for some electrical sub-systems?
The airframe
The electrical supply system consists of how many systems?
Four.
➢ Starter/generator system
➢Battery system
➢Emergency power supply system
➢External power supply system
Where are the AMC’s installed?
in the avionic bay below the cockpit floor
What WARNINGS can you have on the electrical system?
BATT OVERTEMP only
What is the BATT overtemp trigger?
71C inside the battery casing.
What is responsible for the power generation control and protection circuits?
The Generator Control Units (GCU)
What are the current sesnors connected to?
GCU’s & AMC’s to measure current from the generators, battery and EPU
What RPM do the starter windings de-energise?
61% N1
How many brushes are in the generator?
Four
What output do the generators produce?
200A by 26-30V
Where is the TEMP SWITCH located for the generators?
On the mounting flange
What controls the starter gen relays?
The GCU
How is the GCU powered?
by the respective GEN or, backup power is via the ESS BUS
What voltage is an OVERVOLTAGE from the GEN?
exceeding 31.5V
What is an UNDERVOLTAGE?
below 20V
What is an OVERCURRENT?
230A
What is a REVERSE CURRENT?
a reverse current in the circuit.
What is a FEEDER FAULT?
when the current difference between two current sensors (CS1&CS2) is higher than 110 +-11 A