Nexans, ICMAB-CSIC, Tecnalia and UAB have collaborated on the ENDESA Supercable, a 30 m long, medium-voltage superconducting ac power cable. The cable was developed and manufactured within the framework of the ENDESA Novare program. With a rated current of 3200 A, a 3-phase system based on this cable is able to transmit 138 MVA at its envisioned operating voltage of 25 kV. While the cable was designed for 25 kV, the terminations avail able for cable testing were rated for the 20-kV class. Consequently the high voltage tests were carried out at the levels appropriate for 20 kV cable systems. The cable has successfully passed all high voltage and load cycle tests. The load cycles consisted of ten 24-hour cycles during which, with a voltage of 2 - UO applied for the full duration of the 10 test cycles, the rated current of 3200 A was applied for 8 hours. The ac losses of the cable were also measured. The successful prototype testing of the cable confirmed the de sign, manufacturing, and performance of this high transmission capacity cable: To our knowledge, it is the highest ampacity power cable so far that has passed the rigorous load cycle test protocol of a similarly rated conventional cable.