Connecting two plasma relays, Trip sacrifices himself
B'Elanna manually adjusts an EPS relay taken from the transporter systems on the Delta Flyer during its maiden voyage
A plasma relay (also known as an EPS relay) was used to distribute plasma throughout starships and other vessels. They were used on Vulcan, Earth Starfleet, Federation and Dominion ships.
In 2151, several plasma relays on B-deck blew off when Enterprise fired their modified phase cannons at the enemy vessel. (ENT: "Silent Enemy")
Captain Jonathan Archer compared his condition after T'Pau performed a Vulcan ritual on him with "pulling my head out of a plasma relay". (ENT: "Awakening")
In 2161, Commander Charles Tucker connected two live plasma relays aboard the NX-01 Enterprise in an attempt to prevent a group of alien trespassers from killing Captain Jonathan Archer and possibly other crewmembers. The resulting explosion incapacitated the aliens, but the ignited plasma from the relay thermalized Tucker's lungs and he died soon after. (ENT: "These Are the Voyages...")
When a plasma relay was damaged it produced radiation which could be detected by another starship. If the replicator power converter was crossed with the plasma manifold there was a great chance the plasma relay would explode, although this did not happen always. (DS9: "Defiant")
In mid-2371, a plasma relay exploded aboard a Bajoran transport carrying Kai Winn Adami and Vedek Bareil Antos. (DS9: "Life Support")
Around the same time, B'Elanna Torres was working on a plasma relay on the USS Voyager, however, she was taken over by the consciousness of Chakotay in which she was forced to eject the warp core. (VOY: "Cathexis")
As he began to repair the USS Defiant after a Jem'Hadar attack in 2372, Enrique Muñiz uncoupled a plasma relay. (DS9: "Starship Down")
While attempting to remove Borg technology from Voyager, Torres told Seven of Nine to begin removal of the technology from the plasma relays in Jefferies tube 13-Alpha, section 12. (VOY: "The Gift")
Kira Nerys told a Jem'Hadar Seventh to power up a plasma relay slowly when the Defiant was briefly captured by the Dominion in 2374. (DS9: "One Little Ship")
During a battle with a Jem'Hadar attack ship, a plasma relay on deck three of the USS Valiant began to leak. (DS9: "Valiant")
In 2375, Bronok and four other members of the Cardassian Rebellion were ordered by Kira Nerys to plant a bomb in a Jem'Hadar attack ship's plasma relay, but the Cardassians ignored orders and placed it in the intercooler matrix. (DS9: "Tacking Into the Wind")
Harry Kim said his first sight of the Varro Derran Tal was like "touching an open plasma relay". (VOY: "The Disease")