ELECTRICAL - DC

TRU 1 and TRU 2 TOGGLE

AUTO: Automatic operation of the electrical system. Connects TRU 1 (2) to the respective DC bus

OFF: Isolates TRU 1(2) from the respective DC bus

TRU ESS SWITCH

AUTO: Automatic operation of the electrical system. Connects TRU ESS to the ESS BUS 3

OFF: TRU ESS is isolated from ESS BUS 3

NOTE: DC GPU supplies power to only APU START BUS. It does not charge the batteries.

BATT 1 SELECTOR KNOB

ON: Connects Battery 1 to DC ESS BUS 1

OFF: Power is only supplied to HOT BATT BUS 1

HOT BATT BUS 1 powers: Engine 1A and 2A fire extinguisher, engine fuel shutoff valve 1, hydraulic system shutoff valve 1, engine 1 oil level indication, Courtesy/Service lights fwd, DC ceiling lights.

BATT 2 SELECTOR KNOB

AUTO: Connects Battery 2 to DC ESS BUS 2. Allows Battery 2 to power the APU START BUS during APU start.

OFF: Power is only supplied to the HOT BATT BUS 2

HOT BATT BUS 2 powers: Engine 1B and 2B fire extinguisher, engine fuel shutoff valve 2, hydraulic system shutoff valve 2, engine 2 oil level indication, refueling panel, Water and Waste controller, and CMC.

NOTES:

• Supply essential loads for 10 minutes.

• On ground if powered only by batteries for more than 5 minutes a horn will sound.

• Wait to turn the batteries off when leaving the aircraft until the APU off and APU FUEL SOV CLSD EICAS messages are displayed (approx.. 80 seconds).

DC BUS TIES

AUTO: Allows automatic operation of the electrical system.

OFF: DC bus ties open.