The AC ESS XFER switchlight is used to ________.

The AC ESS XFER switchlight serves a specific function in managing the aircraft's electrical system. When activated, it transfers the power source for the AC Essential Bus (AC ESS BUS) to AC Bus 2. This capability is crucial for maintaining power to essential systems in scenarios where the primary power source may become compromised or when a redundancy in power supply is needed.

This switchlight indicates the transition of power, ensuring that critical systems remain operational, enhancing the safety and reliability of the aircraft's electrical system. The understanding of this function is vital for flight crews and maintenance personnel to manage power efficiently in various operational scenarios.

The other choices do not accurately describe the specific role of the AC ESS XFER switchlight. While transferring power source management is its primary function, powering on a generator or isolating the AC system pertains to different aspects of electrical management and operations in the aircraft's systems.