Experimental setup for calorimetric alternating current loss measurements on high-temperature superconductor tapes in applied longitudinal magnetic fields carrying transport currents at variable temperatures

Abstract

In most power devices, the conductor is carrying an ac transport current while it is exposed to an ac magnetic field transverse to the current path. In certain applications, such as multilayer power cables or the control winding in a controllable reactor, the conductors are exposed to a magnetic field component parallel with the current path that is longitudinal to the tape axis. An experimental setup to measure the losses at a different longitudinal magnetic field, transport currents, frequency, and temperature is presented. The system is based on a calorimetric measuring method. Examples are given of power loss measurements on multifilamentary Bi 2223 tapes at different longitudinal ac magnetic fields 0–250 mT peak value, frequencies 0–1000 Hz, ac transport currents 0–70 A peak value, and temperatures 55–85 K. The calorimetric technique presented is fast, accurate, and capable of measuring losses between 0.5–100 mW/m. The data obtained from the apparatus can provide an improved base for the design of power devices.