The HL-LHC “Class 2” high precision current measurement devices, or DCCTs (direct current current transformers), are used for the accurate current measurement/regulation in the 2kA Inner Triplet Trims and Orbit Correctors power converters. The final prototype DCCT, from the IT-4513 HL-LHC contract ([manufacturer:] PM Special Measuring Systems), has been recently validated at CERN and approval was given for the pre-series phase, which consists of another sixteen units for the HL-LHC IT String [being assembled] in SM18.
All performance aspects of the technical specification were evaluated including Electro-Magnetic Compatibility. Most requirements were met in the first version of the prototype, except for the very challenging 12-hour stability requirement (better than 1.5 ppm of the nominal current), due to difficulties with the traceability of magnetic materials for the cores of the DCCT head. To solve these issues, CERN worked in close collaboration with PM Special Measuring Systems to improve the material selection process [for the final assembly of the magnetic cores]. Several iterations of the prototype were evaluated by the SY-EPC-HPM team until the stability problems were solved and a prototype could be successfully validated.
By Miguel Cerqueira and Michele Martino, on behalf of WP6B.
>12h Hour Stability Test Results @0A and @Inom