Ground Power selected ON.

  • Both BTBs close powering Transfer Bus 1 and Transfer Bus 2 and
    the associated Main and Galley busses. GRD POWER AVAILABLE,
    SOURCE OFF and TRANSFER BUS OFF lights extinguish.

  • The Ground Service Relays shift and the Ground Service busses
    are being powered by their respective Transfer busses.

  • TR 1 is being powered by Transfer Bus 1.

  • Tr 2 and TR 3 are being powered by Transfer Bus 2.

  • The Cross Bus Tie Relay is closed and

  • DC Bus 1 is powered by TR1, backed up by TR 2 and TR 3.

  • DC Bus 2 is powered by TR 2, backed up by TR 1 and TR 3.

  • The Battery Bus alternate relay has opened and the Battery Bus is
    powered by TR 3.

  • The DC Standby Bus is powered by TR 1, TR 2 and TR 3.

  • The AC Standby Bus is powered by Transfer Bus 1.
The sequence of bus switching in the Electrical System SGR is for illustrative
purposes only  and is not meant to imply an approved procedure.
Electrical System SGR
Select