24 Electrical Power Flashcards
Describe the B300 electrical system.
28 Volt DC, single loop, triple fed bus with a negative ground.
What components provide your electrical needs?
2 - 28v 300amp Starter gens, 24 volt nicad or 24 volt lead acid.
What are the 5 primary buses?
hot battery bus, center bus, triple-fed bus, left and right generator buses.
Termed a triple fed bus because?
Being fed by 3 primary power sources.
Describe the AC electrical system.
115 VAC & 26 VAC, single phase, 400Hz system, consisting of 2 static inverters, 2 bus transfer relays, ac power monitor circuit, CB’s and annunciators.
During simultaneous operation what happens to the inverters?
They are synchronised.
Power sources for the inverters?
1 - center bus, 2 right gen bus
The bus transfer relays located in the fuel control panel provide what purpose for the AC system?
Manually transfer AC equipment draw from one inverter to the other.
What is the function of the AC power monitor PCB
Monitors both 115/26 VAC buses, both switches and provides power to your #1/2 AC BUS anunciators, closes the sync line
Voltage and frequency regulation?
Voltage - +5% to -7%, freq 400 +/-1%
If a inverter switch is placed to the TRANSFER mode all its load is directed where?
It is shut down and load is transferred to the opposite inverter?
What is the optional AC elec system?
230 VAC 50Hz
What is the purpose of the AC Power Controller?
Distribute to AC power outlets, a RED diag led on the controller indicates a fault.
The DC generation and control system consists of?
2 dual purpose 28 volt, 300 ampere starter gen units for starting and electrical generation.
What would happen if excessive torque is applied at the starter gen spline?
it would shear.
Explain the winding used of the generators.
Series starter winding is used for starting, shunt field winding is used for generation.
Where is the GENERATOR CONTROL PANEL located and what is its purpose?
Main power distribution panel, line contactor relay control, voltage regulation, generator parralelling , differential voltage sensing, reverse current sensing , overvoltage, over excitation, cross starting
Line contactor relay of starter gen system?
each starter gen is connected to its bus by a line contactor relay. the generator control panel will cut power at this relay when a fault is evident.
Starter Gen paralleling
Maintains startgens electrical loads within 10% of each other, by measuring interpole winding voltages
Overexcitation protection
The affected starter gen will be de-energized if generator bus voltage exceeds 28.25 VDC and output differential is greater than 15% for 5 seconds.
Overexcitation protection
The affected starter gen will be de-energized if generator bus voltage exceeds 28.25 VDC and output differential is greater than 15% for 5 seconds.
Reverse current and polarity protection.
If a starter generator is under performing or becoming a load of the system the GCP will open the line contactor relay and remove the affected starter gen from the circuit.
Over voltage protection
If a starter gen exceeds 32.5 VDC, an inverse time delay will trip an internal field de-energizing the affected starter gen. Requiring a manual reset.
What happens if voltage exceeds 40 VDC from a starter generator?
A completly seperate circuit will open the line contactor relay to immediately disconnect the starter gen.
Cross start overload current limiting for starter generators?
limits the output current from the starter gen being used for cross starts
Generator control relay for starter gens?
Located on the main power distribution panel near the generator control panel used for energizing respective contacts in regards to your ON or STARTER ONLY switch.
Generator bus tie and bus sense switches.
pilots outboard sub panel, Analyzes bus voltages and automatically close the generator bus tie relays when no fault exists, bus -sense simulates and overcurrent in the TEST position.
Bus Tie Relays
3 bus tie relays to connect to your battery, left gen and right gen bus ties, located on the aft power distribution panel, battery power distribution panel.
What is the purpose of the 2x DC-DC Converter Power Supply?
Converts to a dual 24 VDC output to power your PFD, MFD, Attitude Heading Computer 1 & 2, During engine start.
What 2 batteries can be used on the aircraft?
Nickel Cadmium (24VDC 36 amph) and Lead-Acid (Recombinant gas 24VDC 42amph)
What charging methods are available for Lead Acid Batteries
Constant potential, constant current
What charging methods are available for Ni-Cad Batteries
Constant Voltage, constant current
How would you charge the batteries still fitted to the aircraft?
Via an external power source at 1/2 of the capacity rate.
How would you charge the batteries still fitted to the aircraft?
Via an external power source at 1/2 of the capacity rate.
What buses are used to form the single loop triple fed system?
L & R Generator busses and battery bus.
What are the positions of your battery bus and generator busses?
Battery bus = cockpit fuel control panel, generator busses = aft of the engine firewall, center bus = forward center aisle floor
Where does your avionics power distribution come from?
co pilots circuit breaker panel.
Where is the main power distribution panel located?
Centre aisle floorboard in-between emergency exits.
What may be used to power the primary buses during ground operations?
GPU
What is the triple fed system protected by?
Current limiters and bus-tie relays
The battery bus and generator buses are all tied together by?
The center bus
