Emitter relay
Emitter relays were components of tractor beams utilized aboard Starfleet vessels in the 24th century.

In 2371, the crew of the  attempted to modify their existing tractor beam to penetrate the event horizon of a type-4 quantum singularity. Doing so, however, overloaded the relays on the power grid, causing the emitter relays to lock. This necessitated Lieutenant Joe Carey physically cutting the main power feed. ()
Spacecraft components