The translocator was an extremely advanced transporter created by the Nyrians of the Delta Quadrant.
Although incredibly powerful and precise, despite its 10 light-year range, the device was limited in only that it could transport one person at a time. It also required a recharge cycle, making transportations possible only once every 9 minutes and 20 seconds.
The Nyrians employed the device to gradually replace the crew of a vessel. Initially they claimed to be surprised by their sudden relocation, but, when sufficient numbers of Nyrians were aboard, they would take over the vessel and remove the rest of the crew.
The main control of the translocator was found on the Nyrian biosphere vessel and it was here that the removed crew were placed.
The device was permanently disabled in late 2373 by crew of the USS Voyager. (VOY: "Displaced")