[en] It was decided in 1983 to expand the CERN ISOLDE facility by the addition of a second primary proton target station, together with a second on-line isotope separator and experimental zone, thereby reserving the CERN synchro-cyclotron almost exclusively for ISOLDE for the future. The main requirements of the new separator were that it should feed a new experimental hall without the constraints of the existing underground zone; that the switchover between the 'old' and 'new' ISOLDE be rapid; that the possibility of high resolution be incorporated; that the use of existing sources, as well as high current ion sources be possible; and that the overall cost be kept low. Of these constraints, the last one was mainly responsible for the way the new separator ISOLDE 3 now looks. Progress has been good, and the separator is being installed at the time of this Conference. (orig.)