What is a "bus-tie" in an aircraft power distribution system?

A "bus-tie" in an aircraft power distribution system refers to a connection between multiple power sources. This connection allows for the sharing of electrical power between different buses or circuits within the aircraft, ensuring that if one power source fails or is taken offline for maintenance, another can take over, maintaining system reliability and functionality.

In the context of aviation, having such a tying mechanism is crucial for redundancy and enhancing safety; it ensures that critical systems remain powered even in the event of a failure of one power source. This system can effectively balance the load and provide continuous electrical support, which is vital for the smooth operation of the aircraft's systems.

The other options describe different components or functions that are not directly related to the specific role of a bus-tie. For instance, an automatic transfer device is not synonymous with a bus-tie since it implies an active management system rather than a simple connection. A circuit breaker serves safety functions by interrupting current flow to prevent overloads, and a battery charger specifically relates to recharging batteries rather than facilitating power distribution across established circuits.