MD-11 Flight Crew Operations Manual
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Electrical -
Controls and Displays
Elec.30.4
8. DRIVE 1/2/3 DISC/FAULT Switch - amber
The generator DRIVE switch (guarded) is a momentary contact switch that
disconnects the IDG through the generator control unit when the system is in
auto and manual mode.
FAULT illuminates amber when a situation requiring an IDG disconnect has
occurred.
DISC illuminates amber when an IDG disconnect has taken place. DISC
extinguishes when the light illumination logic is reset through the CFDS
interface with the EPCU or after the IDG input spline is mechanically
reconnected and the engine is run up to about ground idle.
CAUTION: Do not disconnect an IDG with engine speed less than
ground idle. Disconnecting an IDG with engine speed less than
ground idle will cause damage to the IDG input shaft and seal.
9. GEN 1/2/3 ARM/OFF Switch - blue/amber
The GEN switch is a momentary contact switch that resets the respective
generator when the electrical system is in the manual mode. Switch has no
effect if system is in auto mode.
OFF illuminates amber when the generator control relay is tripped open.
ARM illuminates blue by pushing the GEN switch from the off position. This
initiates a generator control unit to close the generator relay when the
generator power is correct. Switch position automatically reverts to OFF
when a protective trip of the generator relay occurs in the ARM/reset position.
When ARM is illuminated, the generator control relay is closed and the
generator relay is open.
The GEN switch is blank when the generator relay is closed.
10. Emer Pwr OFF/ARM/ON Selector and OFF/ON Light - amber
The EMER PWR selector is a three position selector. It operates when the
system is in the auto or manual mode as follows:
With the selector in the OFF position the main battery is not allowed to supply
power to the left emergency ac and/or dc bus. OFF will illuminate amber.
With the selector in the ARM position the main battery is automatically
transferred to the left emergency ac or dc bus when the system conditions are
correct. ON will illuminate amber upon transfer. Conditions required for an
automatic transfer are:
• BAT switch in ON position.
October 02, 2006
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