AC Losses in Bi 2 Sr 2 Ca 2 Cu 3 O 10+x Tapes and a 3.15-m-Long Single-Phase Cable

The critical current of the tapes used in the cable was measured by a standard four-probe direct-current method averaging both current directions and using the standard criterion defining Ic at a voltage drop of 1 μV/cm. Thirty one tapes from the same batch of tapes were used to construct the cable. From this batch of tapes, 13 samples were selected to be tested in detail in single tape configuration. The Ic of the tapes was found to be 132 ± 6 A. The ac losses in the tapes were measured using the electrical method, being faster and more accurate than calorimetric ones [10], [11], using a 60-Hz ac. A lock-in amplifier extracted the first harmonic I(t )= Ip sin(ωt) from the signal, giving a voltage drop over the tape of U (t )= RIp sin(ωt )+ LIpω − Ip