What occurs when two different power sources are connected to the same side of the synchronous bus on the ground?

What occurs when two different power sources are connected to the same side of the synchronous bus on the ground?

• A. The SSB is commanded to open or close to ensure all AC main busses are powered on the ground
• B. The SSB is left in whatever state it was already
• C. The bus powers both sides equally without switching
• D. The aircraft automatically shuts down the power sources

Answer: (A)

When more than one power source is tied to the same side of the synchronous bus on the ground, the system must control that connection to prevent backfeeding and to guarantee proper distribution of power to the AC main busses. The synchronous bus switch (SSB) is the device that makes or breaks that connection. By commanding the SSB to open or close, the system selects and isolates the appropriate source so all AC main busses receive power safely from the intended source, without cross-feeding between sources. Leaving the switch as-is could allow backfeed or an unsafe parallel of sources, and the other options describe states or behaviors that don’t provide the controlled, safe power arrangement required in this scenario.

When more than one power source is tied to the same side of the synchronous bus on the ground, the system must control that connection to prevent backfeeding and to guarantee proper distribution of power to the AC main busses. The synchronous bus switch (SSB) is the device that makes or breaks that connection. By commanding the SSB to open or close, the system selects and isolates the appropriate source so all AC main busses receive power safely from the intended source, without cross-feeding between sources. Leaving the switch as-is could allow backfeed or an unsafe parallel of sources, and the other options describe states or behaviors that don’t provide the controlled, safe power arrangement required in this scenario.