ELECTRICAL SYS Flashcards
UPDATE: 21MAY25 (18 cards)
NATOPS
AC GENERATORS
Primary ac Electrical power is supplied by:
two transmission driven oil-cooled and lubricated, 30/45kVa, 115Vac, 3-phase, 400 HZ generators.
APU - 35kVa, 115Vac, 3-phase, 400HZ
2.6.2
NATOPS
GCUs regulate/protect against what?
The GCU:
- Connects each genenrator to the bus system
- Regulate generator output
- Protect against over voltage/undervoltage
- Feeder fault
- Underfrequency
2.6.2
NATOPS
GCU Underfrequency Protection
WOW - GCUs remove main generators from the AC system if Nr < 94%
In flight - protection disabled, generators remain online until Nr < 80%
Minimum of 97% Nr required for GCU to reconnect the generators
2.6.2
NATOPS
External Power Receptacle
Provides a connection to energize the entire electrical system when it is the sole source of power.
External power is monitored for
- phase rotation
- overvoltage/undervoltage,
- underfrequency/overfrequency
# The external power system includes a 4-amp circuit breaker that places a 2-amp draw on the power cable
2.6.2
Normal AC BUS distribution
1 AC GEN
- NO 1 AC PRI
- AC ESNTL
- AC SEC BUS
- No 2 AC PRI
- AC MON
2.6.2
NATOPS
Electrical bus load shedding priority
If electrical power demand exceeds the capacity of the generator operating normally, the busloads are distributed to available generator by:
1. Backup hydraulic pump (major load on #1 AC PRI) will always be powered, if required
2. Mission avionics system is the major load on the AC SEC bus. T/R De-Ice is also powered by this bus.
3. M/R De-Ice - only system on the AC Monitor
2.6.2
What can be powered if you only have one generator and the APU?
Think of bus load shedding
-B/U Pump and MSN Pwr: On
all busses except AC MON
- MSN Power (No B/U Pump)
All busses powered
- MSN Pwr OFF B/U Pump ON
All busses powered
You have to choose two items:
MSN PWR & B/U Pump
MSN PWR & T/R De-ice
B/U Pump & T/R De-ice
What can be powered if you only have one generator?
B/U Pump or AC Secondary
What can be powered if you only have the APU?
NO 1 AC PRI
NO 2 AC PRI
AC Essential
2.6.2
What is the main power supply to the DC system?
Two converters that supply 28Vdc by converting 115Vac from the #1 and #2 AC primary buses.
2.6.3
What is the primary source of power for APU starts?
Tthe 24Vdc battery - used for APU starts, and is a secondary power source for the DC essential and battery buses
2.6.3
Battery Charge percentages and what it gives you/ what you loose
80% charge - 11 min day, 9 min night
40%- BATTERY CHARGE LOW caution
35% - Below this DC ESNTL BUS dropped
30% - Fire Extinguisher CAD may not actuate
2.6.2-2.6.3
Componenets on the DC ESNTL
- Manual STAB Slewing
- All Internal lighting
- EMER RELEASE
The battery analyzer / conditioner monitors and provides what?
- Fault conditions
- Battery charge
- Internal temp
- Cell conditions
- Battery charging capability
2.6.3
Where does the battery analyzer / conditioner receive power from?
With converters operating and BATT ON:
- PWR: NO 2 AC PRI BUS
- DC CHRG PWR: NO 2 DC primary bus
2.6.3.1
What is the difference between a single and a dual converter failure?
Single converter fail - the operating converter picks up the load dropped by the failed converter
Dual converter fail - battery becomes emergency power source to the utility bus, battery bus, and the DC essential bus until less than 35% charged.
Normal DC BUS distribution
1 DC Converter:
- # 1 DC PRI
- DC ESNTL
- BAT BUS
#2 DC Converter: - # 2 DC PRI#BATTERY:
- UTIL BAT BUS
Figure 2.6-3
In a dual converter failure, what can you expect to lose?
Both Flight and mission displays
Anti-ice valves (Inlet and eng) stuck open ( loss of 49% power)
- DTU 1&2
-AFCS computer and control
- Jettison power
- Aux fuel and fuel management
- Backup pump operation
- Rast probe
- #1 EGI (AFCS functionality)
12.9.1
How long after complete electrical loss will the B/U attitude indicator be operable
Up to 9 minutes
12.9.1
