Electrical Systems - Aircraft

Electrical Systems - Aircraft

• Cancelling messages: Crew can cancel displayed company or ATC uplink messages by pushing the CANC/RCL switch on the display panel, or selecting CANCEL command on the MFD COMM page.
• ATC reports: LEAVING FL330 and PASSING SEA are ATC requested reports that can be armed for automatic downlink to ATC. MAINTAINING FL330 is not.
• Airplane (cold) power-on: The APU controller and the DC fuel pump will be powered if the BATTERY switch is ON on a cold airplane (no power connected). Only the main battery bus will be energized - not the hot battery bus
• AC power loss: Standby busses and emergency lights are powered when the BATTERY switch is ON if AC power is removed or lost. This also includes critical AC and DC power.
• Generator control: An amber OFF light on the generator control switch indicates the generator breaker is in the open position, not that the generator is working correctly or has failed..
• BUS TIE ISLN: The BUS TIE ISLN will illuminate if the switch position changes to OFF or a fault develops - not when the switch is ON or a fault does not occur.
• Utility electrical bus isolation: Utility electrical buses can be isolated in flight or on the ground during high electrical load conditions.
• Generator drive lights: Generator drive lights illuminate when there is low IDG oil pressure. High oil pressure will not activate the lights. Minimum pressure will not activate the lights.
• Transfer bus separation: The right transfer bus separates from the main right AC bus to provide independent autopilot power for approach when TAKEOFF is selected on the TOGA. or if APPROACH is selected for AUTOLAND or when VNAV is selected on the MCP panel.
• Backup generator operation: Both backup generators can work at the same time.
• Backup generator activation: A backup generator works if only one generator is available and if power is lost to one or both main AC buses.
• Backup generator light: The BACKUP GEN “OFF” light illuminates when a fault is detected and when the system is selected to OFF.
• Autoland and APU power: Autoland is available if both generators are unpowered but an APU is available.
• ELMS (Electric Load Management System) function: The ELMS system is used for electrical load management.
• APU power and BUS TIE: If an APU starts with external power on the BUS TIE system, the APU connects to the BUS TIE and replaces the secondary external power on the left main bus. This also relates to power sourced when one engine is off, the other is on or the APU is active in different power setups.
• Engine starting and bus power: If the left engine is on and external power powers the right bus, the right engine generator automatically powers the right main bus, not both main buses.
• Ground handling bus operation: Ground handling bus is activated for operation on the ground, and the bus is powered as long as the right main AC bus is active.
• External power and ground handling buses: No external power source is required for the ground handling bus if the right main AC bus is active and present, or for AC busses, however, a GRD handling bus will.
• Primary DC power source: Transformer rectifier units are the primary source of DC power during normal flight.
• DC power source: Transformer rectifier units provide DC power to the aircraft.
• Right transfer bus isolation: The right transfer bus isolates from the right main AC bus when the system configures to autoland
• Fly-by-wire primary, secondary power source: The primary power source for fly-by-wire is Main AC busses. The secondary source is the left transfer bus if one or more PMGs are unpowered.
• Standby power: If all normal AC and DC power sources fail, the backup generators are the primary standby power source