To preserve the power supply to the DC power buses when a TRU fails, ________ causing power to be routed to the affected buses.

• A. Ties Close
• B. Ties Open
• C. Open Circuit
• D. Short Circuits

Answer: (A)

Closing the ties between the DC power buses creates a cross-feed path that lets the healthy transformer-rectifier units continue to energize both buses even if one TRU fails. This preserves power to loads that would otherwise be unpowered by routing the remaining supply to the affected bus. If the ties stayed open, the buses would be isolated and could lose power on the affected side. A short circuit would introduce faults and isn’t how transfer is achieved. So, closing the ties provides the necessary alternate path to maintain power distribution.