MD-11 Flight Crew Operations Manual
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Electrical -
Controls and Displays
Elec.30.5
• SMOKE ELEC/AIR Selector not in 1/2 OFF position (Generator channel
1 de-energized).
• Left emergency ac or dc bus de-energized.
With the selector in the ON position, the left emergency ac and dc buses are
transferred to battery power. ON will then illuminate amber.
If this selector is in ARM when the aircraft electrical power is shutdown, the
emergency circuits will remain activated, resulting in depletion of the aircraft
batteries.
NOTE: If emergency power automatically transfers ON and then normal
power is restored, this selector must be cycled OFF and back to
ARM to allow the L emer buses to be powered by the main generator
bus. If this is not done, the L emer buses will continue to be powered
by the aircraft batteries.
11. BAT OFF Switch - amber
The BAT switch is a guarded, alternate action switch that disconnects the
battery from the battery bus and battery charger. This switch is normally on
and operates the same when the system is in the auto or manual mode.
When the switch is on, battery charger is allowed to charge the main battery
if:
• Battery power is not supplying the left emergency dc bus or (through the
static inverter) the left emergency ac bus.
• Inverter powered ground refueling is not taking place.
• Transformer rectifier bus 2A or transformer rectifier bus 2B is energized
or the ground service relay is closed into the APU or EXT PWR position.
• Ac power is present at battery charger input.
When the switch is on, battery is connected to the battery bus if:
• Transformer rectifier bus 2A and transformer rectifier bus 2B are not
energized.
• Ground service relay is not closed into APU or EXT PWR position.
The switch illuminates amber when pushed into the OFF position. The battery
is then disconnected from the battery bus and is not allowed to be charged by
the battery charger. Automatic transfer of emergency power to the left
emergency ac or dc buses is inhibited.
12. BAT BUS OFF Lights (13) - amber
Illuminates amber when associated ac or dc bus is deenergized. There is one
light for each ac or dc bus.
October 02, 2006
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