The Translocator was an extremely advanced transporter created by the Nyrians of the Delta Quadrant.
Although incredibly powerful and precise, it lost power over long distances and, at a range of around 10 lighyears, could only transport one person each way. It also required a recharge cycle making transportations possible 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 habitat ship and it was here that the removed crew were placed.
The device was permanently disabled in late 2373 by the crew of the USS Voyager. (VGR: "Displaced")