Deflector field
A deflector field was the energy field created by the deflector array of a starship. A deflector field was typically initialized automatically, though in extreme circumstances, it had to be activated manually.

When the 's computer systems were rendered inoperable by a cascade virus in 2373, the deflector field had to be manually initialized by the bridge crew when the ship undocked from Deep Space 9. ()

The deflector field had to be manually activated on a severely damaged  during the Year of Hell, after a Krenim scientist altered history in 2374. This was done to prevent further damage from a micrometeoroid field. This timeline was negated when the Krenim weapon ship was deleted from history. ()
 Energy