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.
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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