BAT 1/2 Switches
Controls the operation of the corresponding battery charge limiter.

• AUTO - The Batteries are automatically connected to the DC BAT bus during the following:
  • APU starting
  • Battery charging
  • Below 100 knots on the ground with a loss of AC buses 1 and 2
• OFF - The Battery charge limiter is not operating and the battery line contactor is open. The OFF light illuminates white provided the DC BAT bus is powered. The HOT BAT buses remain powered.
• Fault Light - Illuminates amber when the charging current for the corresponding battery increases at an abnormal rate. In addition, the battery contactor opens.

Galley Switch

• AUTO - The Galleys are electrically powered. The main Galley bus is automatically shed when only one generator is operating, except on the ground when the APU or external power is available.
• OFF - The Galleys are not electrically powered.
• Fault Light - Illuminates amber when any generator load is above 100% of its rated output.

AC ESS Feed Switch
Enables the AC ESS BUS to be powered via AC BUS 2 instead of AC BUS 1.

• Normal - AC ESS BUS is supplied from AC BUS 1.
• ALTN - AC ESS BUS is supplied from AC BUS 2.
• Fault Light - Illuminates amber when the AC ESS BUS is not electrically powered.

APU GEN Switch

• ON - The Generator field is energized and the line contactor closes provided electrical parameters are normal and the EXT PWR line contactor is open. The bus tie contactor (1 and/or 2) automatically closes if generators 1 and/or 2 are not operating.
• OFF - The Generator field is de-energized and the line contactor opens. The fault circuit is reset.
• Fault Light - Illuminates amber if a protection trip is initiated by the Generator control unit (GCU), or the line contactor opens without selecting the APU GEN switch OFF. The APU GEN FAULT light is inhibited when APU speed is low.

BUS TIE Switch

• AUTO - The Bus Tie contactors open or close automatically to maintain power supply to AC buses 1 and 2.
  
  One contactor is closed when one engine-driven generator supplies the associated AC bus and the APU generator or external power supplies the other side.
  
  Both contactors are closed in case of one engine-driven generator, or external power supply.
• OFF - Both Bus Tie contactors are open.

EXT PWR Switch
When pushed with the EXT PWR AVAIL light illuminated:

• External Power line contactor closes
• AVAIL light goes off
• ON light illuminates

When pushed with the EXT PWR ON light illuminated:

• External Power line contactor opens
• ON light goes off
• AVAIL light illuminates

AVAIL Light - Illuminates green provided External Power is plugged in and electrical parameters are normal.

BAT 1/2 Indication Window
Display the Battery voltage

IDG 1/2 Switches ( Guarded )
Normally springloaded out. When pushed, the IDG is disconnected from its drive shaft and can only be reconnected by Maintenance.

GEN 1/2 Switches

• ON - The Generator field is energized and the line contactor closes provided electrical parameters are normal.
• OFF - The Generator field is de-energized and the line contactor opens. The fault circuit is reset.
• Fault Light - Illuminates amber if a protection trip is initiated by the Generator control unit (GCU), or the line contactor opens without selecting the respective GEN switch OFF.