Which action automatically powers both the DC Battery Bus and the DC Essential Bus when ESS TRU 1 and ESS TRU 2 fail?

• A. Closure of the ESS TIE and CROSS TIE
• B. Activation of the ADG
• C. Opening of the ESS TIE
• D. Manual reset of DC buses

Answer: (A)

The action relies on automatically linking the DC Battery Bus to the DC Essential Bus through the bus ties. When ESS TRU 1 and ESS TRU 2 fail, closing the ESS TIE and CROSS TIE creates a direct power path from the Battery Bus to the Essential Bus, so essential loads stay powered and the battery bus remains active as well. Opening these ties would cut that connection, and relying on the ADG alone wouldn’t guarantee both buses are powered automatically. A manual reset isn’t required because this tie closure is designed to happen automatically to preserve critical power distribution.