During what scenario might a black start unit be utilized?

A black start unit is specifically designed to restore electrical power without assistance from the external power grid. This capability is crucial during a scenario involving a widespread outage, where the electrical grid has collapsed and requires a method to initiate power restoration. Black start units are typically smaller, independent power sources that can begin operating from a shutdown state and can power up larger generation units or transmission systems.

In the context of restoring power, these units can help re-establish the initial conditions necessary to bring additional generation resources online in a controlled and systematic manner, ultimately aiding in the restoration of the entire grid. Other scenarios, such as routine maintenance, replacing aging plants, or normal load management procedures, do not necessitate the use of black start capabilities since those processes occur under normal grid operation conditions where power is available.