Standby Power Selector

• OFF - Disconnects the main and APU Standby buses from all power sources.
• AUTO - Allows the main Standby bus to be powered automatically from AC bus 3.
• BAT - Powers the main and APU Standby buses from their respective batteries through their hot battery busses and Standby inverters.

Utility Power Switches

• ON - Each switch powers two galley and two utility buses if no load shedding signal is present.
• OFF - Disconnects the two galley and two utility buses from AC power and reset fault circuitry.
• Lights - Indicate that one or more buses are unpowered, either automatically by protective circuits or by turning the switch off.

APU Selector

• OFF - Closes APU bleed air valve, initiates automatic shutdown sequence and resets fault detection logic.
• ON - APU operating position.
• START - Initiates automatic Start sequence. Spring-loaded from START to ON.

Battery Switch

• ON - Enables the main and APU batteries to provide backup power to the main and APU battery buses and the main and APU standby buses.
• OFF - Disconnects main and APU batteries from respective battery buses.
• OFF Light - Indicates the BATTERY switch is OFF.

BUS TIE Switches

• AUTO - Allow Bus Tie breaker and respective DC isolation relay to close automatically when system logic permits.
• OFF - Open the Bus Tie breaker and respective DC isolation relay.
• ISLN Lights - Indicate the respective AC Bus is isolated from the Tie Bus as the Bus Tie breaker has opened due to a fault, or the switch is off.

GEN CONT Switches

• ON - Close Generator field and allow the Generator control breaker to close automatically when system logic permits.
• OFF - Open Generator field and Generator control breaker. Reset fault trip circuitry.
• OFF Lights - Indicate Generator control breaker is open.

Drive DISC Switches
Disconnect the IDG from the engine. Can only be reconnected on the ground.

• Lights - Indicate generator Drive has low oil pressure or excessive oil temperature.

EXT PWR Switches
Open or close the External power contactor if the AVAIL light is on.

• ON Lights - Indicate external power contactor is closed.
• AVAIL Lights - Indicate External power is plugged in and the voltage and frequency are within limits.

APU GEN Switches
Open or close the auxiliary power breaker if the AVAIL light is on.

• ON Lights - Indicate APU power breaker is closed.
• AVAIL Lights - Indicate output voltage and frequency of the APU generator are within normal limits.