The 18 DTT Toroidal Field (TF) coils must be fed by a high-stability 42.5 kA current. The contract for the procurement of the TF Power Supply was assigned to JEMA (a Spanish company) in 2022. According to the Technical Specification, the most critical devices have to be tested with the supervision of the DTT experts before the delivery.

A first set of tests was successfully performed in the premises of the JEMA sub-supplier TMC (Fabbro, Italy), on a pair of smoothing reactors (Images 1 and 2), assembled in the same configuration designed for DTT.

A second set of tests was successfully carried out in the Tecnalia Certification Lab (Zamudio, Spain), on the first of the four custom transformers of the TF converters. The test campaign included a reproduction of a complete short-circuit (Image 3), to verify the capability of the transformer overcome the critical event without losing its functional characteristics.

In any case, all the most critical components of the Power Supply System, after the delivery, will be verified in the Frascati Coil Cold Test Facility, a new laboratory designed to test the superconductors in operative conditions (full current and temperature close to -270 °C).