ELECTRICAL SYSTEMS Flashcards
The DC Starter Generator / The ACW Generator
The DC Starter Generator is driven by the HP spool throught the Accessorry Gear Box (AGB)
– From 0 to 45% NH as a Starter
– Above 61.5% as a Generator
The ACW Generator is driven by the Reduction Gear Box (RGB), and is available when NP > 66%
ACW in HOTEL mode
In Hotel Mode or with the propeller feathered, there is no ACW.
When the propeller is unfeathered (CL in AUTO /100% OVRD), The NP is maintained at a minimum of 70,8%, in order to have ACW (minimum 66%)
DC-AC SCHEMATIC
NORMAL SUPPLY: ON GROUND WITH BATTERY ONLY
The GOUND HANDLING BUS is supplied only on
ground, by three different ways:
– BAT OFF or BAT ON with the EXT PWR not avail- able, the GND HDLG BUS is supplied by the HOT MAIN BAT BUS for ground servicing only when:
- The refueling panel is open
- The cargo door control panel is open
- The passenger door is open
– BAT OFF or BAT ON with the EXT PWR available but not ON, the GND HDLG BUS is supplied from the EXT PWR via the DC SVCE BUS
– BAT ON with EXT PWR ON or with one GEN on line, the GND HDLG BUS is supplied by the from the DC BUS 1 via DC SVCE BUS.
NOTE: The GND HDLG BUS is disconnected when airborne.
ELECTRICAL SYSTEMS
NORMAL SUPPLY: ON GROUND WITH EXTERNAL POWER
The BTC is closed and the GPU supplies all the DC and AC busses. Even if the GEN are available, the GPU has always priority.
ELECTRICAL SYSTEMS
HOTEL MODE OR DC GEN 1 FAULT
The BTC is closed and the GEN 2 supplies all the DC and AC busses.
In hotel mode the GND HDLG BUS is supplied by the DC BUS 1 through the DC SVCE BUS.
ELECTRICAL SYSTEMS
NORMAL SUPPLY: WITH TWO GENERATORS ON LINE
The BTC is opened and each GEN supply its respective busses.
On ground the GND HDLG BUS is supplied by the DC BUS 1 through the DC SVCE BUS, and disconnected when airborne.
EMERGENCY SUPPLY: IN DUAL DC GEN LOSS WITH THE BATTERY TOGGLE SWITCH ON OVRD
The BAT toggle switch has to be selected to OVRD.
The OVRD position ensures that busses are supplied by their respective battery by overriding all protections. This position is protected by
a switch guard.
EMERGENCY SUPPLY: IN DUAL DC GEN LOSS WITH THE BATTERY TOGGLE SWITCH ON OVRD AND SECOND OVRD SELECTED
After a Dual DC GEN loss, the UNDV is triggered when the DC STBY BUS <19,5 V.
Then, by pushing on the OVRD the DC and AC STBY BUS are transfered from the HOT MAIN BAT BUS to the HOT EMER BAT BUS.
When passing to OVRD, the DC STBY BUS voltage is recovered and the UND/V extinguishes.
EMERGENCY SUPPLY: IN DUAL DC GEN LOSS WITH TRU
The TRU connected to the ACW BUS 2 supplies
DC EMER BUS, DC ESS BUS, DC&AC STBY BUSSES.
ACW SCHEMATIC
ACW supplied by the External Power
– When the AC GPU is available (AVAIL) but not ON, the GPU supplies only the ACW Service Bus, if the GND Service Bus switch, on the flight attendant panel, is ON.
– When the AC GPU is ON, the GPU supplies through the BTC, the ACW BUS 1, the ACW BUS 2 and the ACW SVCE BUS.
– Even if one ACW generator is available, the GPU has always priority.
ACW in Hotel mode or with the propeller feathered
ACW in Hotel mode or with the propeller feathered
NOTE: An ACW Generator is available if the NP is above 66%.
– When the right engine is running in hotel mode, the NP=0.
– When the engines are running but the propellers are feathered, the NP is bellow 20% In both cases the ACW Busses are not supplied
The propeller unfeathered and one ACW GEN on line
The propeller unfeathered and one ACW GEN on line
On ground, when the propeller is unfeathered, the engine is running on fuel governing mode.
The fuel governing mode, maintain a minimum NP of 70.8%, in order to have the ACW available (ACW GEN on line at 66%)
The ACW GEN supplies, the ACW BUS 2 and ACW BUS 1 through the BTC, but the SVCE BUS is shed (one generator is not able to supply all the busses)
CAUTION: on ground in case of an EEC or PEC fault, the fuel governing mode is lost and the ACW generator is not available (NP<66%)
ACW Normal condition in flight
Normal condition in flight
– The ACW GEN 1 supplies the ACW BUS 1 and the ACW SVCE BUS
– The ACW GEN 2 supplied the ACW BUS 2.
– The TRU is connected to the ACW BUS 2
ACW One Generator Fault
ACW One Generator Fault
When one generator is fault, the other one supplies the ACW BUS1 and the ACW BUS 2 through the BTC.
The SVCE BUS is automatically shed (one generator is not able to supply all the busses)
