Saab 340B, Руководство по эксплуатации

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ELECTRICAL
Description
Aircraft Operations Manual
5.1
PAGE 5
Jun 01/19
MAIN INV light on the overhead panel comes on. In
this case, the standby inverter can be selected by
placing the 26V inverter switch to STBY INV. The
standby inverter will then supply the L and R INV
BUS 26V AC from the R MAIN BUS. The L and R
INV BUS 115V AC will however remain powerless.
Applicable with two main inverters installed
The a/c is provided with two main inverters 115
V/26 V 400 Hz.
By selecting INVERTER 1 or 2, anyone of the two
inverters will supply power to:
− L and R INV BUS 115 V AC;
− L and R INV BUS 26 V AC.
If the DC supply to the selected operation inverter is
interrupted or if the inverter fails, the INVERTER
light on the overhead panel comes on. In this case
select the other inverter.
With Mod No 2544 installed (power supply changed
for ACARS COM3 and the inverters). The power
supply for the inverters are changed from L and R
MAIN BUS to L and R BAT BUS. The selected in-
verter might trip during engine battery start due to
battery voltage drop and must be reset after engine
start if tripped.
2.9 Wild frequency AC system (Fig. 10)
The wild frequency 115V AC system is for ice
protection only. ”Wild” is because the frequency is
variable between 460 to 600 Hz due to variations in
propeller rpm. There is one AC generator installed
on each propeller gearbox and it is cooled by ram
air during flight and by an integral fan on the
ground.
The generator drive shaft has a shear point which
will separate the generator drive shaft from the ac-
cessory drive gear in case of high mechanical over-
loading.
Each generator is connected to the respective L/R
AC GEN BUS through an AC generator relay and
controlled by a control unit. The control unit regu-
lates the voltage to 115V and also provides fault
protection.
Either of the two generator relays automatically ties
the two generator busses together when one gener-
ator is inoperative, or manually by means of the L/R
AC GEN switches on the overhead panel.
If a generator fails or disconnects from the L/R AC
GEN BUS due to too low propeller rpm, it’s AC
GEN light on the overhead panel comes on. The
generator automatically resets when the propeller
rpm increases again and the AC GEN light goes
out.